Transportation Research Part D 92 (2021) 102717
交通研究D 部分 92 （2021） 102717

Anil K. Madhusudhanan^*, Daniel Ainalis, Xiaoxiang Na, Isabel Vallina Garcia, Michael Sutcliffe, David Cebon
Anil K. Madhusudhanan^*、Daniel Ainalis、Xiaoxiang Na、Isabel Vallina Garcia、Michael Sutcliffe、David Cebon

Department of Engineering, University of Cambridge, Trumpington Street, Cambridge CB2 1PZ, UK
剑桥大学工程系，Trumpington Street，剑桥 CB2 1PZ，英国

A R T I C L E I N F O  A B S T R A C T

Introduction
介绍

There are numerous technological opportunities in the short to medium term to improve the fuel efficiency of Heavy Goods Vehicles (HGVs) (Delgado et al., 2017). While tractors are often the focus of research and development into fuel efficiency technologies, trailers are generally considered as an afterthought due to their relatively low cost. Trailers play a vital role in road freight transport (McKinnon, 2006) and should be included in strategies to reduce the carbon emissions produced by the sector (Galos et al., 2015). Broadly speaking, three main technologies are available to reduce fuel consumption of trailers: low rolling resistance tyres, aerodynamic packages to reduce drag, and light-weighting using new and alternative materials to reduce mass and increase payload (Greening et al., 2015).
在中短期内，有许多技术机会可以提高重型货车 （HGV） 的燃油效率（Delgado 等人，2017 年）。虽然拖拉机通常是燃油效率技术研发的重点，但由于成本相对较低，拖车通常被认为是事后才想到的。拖车在公路货运中起着至关重要的作用（McKinnon，2006 年），应纳入减少该行业产生的碳排放的战略（Galos 等人，2015 年）。从广义上讲，有三种主要技术可用于降低拖车的燃料消耗：低滚动阻力轮胎、减少阻力的空气动力学包，以及使用新材料和替代材料实现轻量化以减轻质量并增加有效载荷（Greening 等人，2015 年）。

Aerodynamic drag is a significant component of energy consumption, particularly in long haul operations due to the high average speeds (Zhao et al., 2013; Lajunen, 2014). The aerodynamic drag is dependent on the design of the tractor and trailer, and the interaction between them. In (Wood and Bauer, 2003), the four primary sources of aerodynamic drag and their respective percentage contributions for a tractor-trailer are outlined: the tractor front (25%), the gap between the tractor-trailer (20%), the trailer’s underbody (30%), and the rear of the trailer (25%). Due to the considerable difference in tractor and trailer bodies in North-America and
空气阻力是能源消耗的重要组成部分，尤其是在长途运营中，由于平均速度高（Zhao 等人，2013 年;Lajunen，2014 年）。空气阻力取决于拖拉机和拖车的设计，以及它们之间的相互作用。在（Wood 和 Bauer，2003 年）中，概述了空气动力阻力的四个主要来源及其对牵引拖车的相应百分比贡献：牵引车前部 （25%）、牵引车拖车之间的间隙 （20%）、拖车底部 （30%） 和拖车后部 （25%）。由于北美的拖拉机和拖车车身存在相当大的差异，并且

This research was partly supported by the Innovate UK Grant RG87919: ‘Low Emission Freight and Logistics Trial - Lightweight Aerodynamic Double-Deck Trailer Trial’ and the Engineering and Physical Sciences Research Council Grant EP/R035199/1: ‘Centre for Sustainable Road Freight 2018-2023’.
这项研究得到了 Innovate UK Grant RG87919：“低排放货运和物流试验 - 轻型空气动力学双层拖车试验”和工程与物理科学研究委员会 EP/R035199/1：“2018-2023 年可持续公路货运中心”的部分支持。

* Corresponding author.
* 通讯作者。

E-mail address: ak2102@cam.ac.uk (A.K. Madhusudhanan).
电子邮件地址：ak2102@cam.ac.uk （A.K. Madhusudhanan）。

https://doi.org/10.1016/j.trd.2021.102717

Available online 9 February 2021
2021 年 2 月 9 日在线提供

1361-9209/© 2021 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY license
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(http://creativecommons.org/licenses/by/4.0/).

the UK, e.g. long-nose tractor and variable tractor-trailer gap in North-American HGVs are not present in HGVs in the UK, the potential contributions can be different for HGVs in the UK. Nevertheless, a variety of technology packages are available to reduce the drag across all these sources. They include streamlining the shape of the tractor and trailer, adding side panels and fairings, and even complete redesigns which could theoretically reduce the drag coefficient by 42% in the long-term (Delgado et al., 2017). Note, however, that any reduction in payload due to changing the shape can have a negative effect on overal energy consumption. So such large drag reductions are not necessarily beneficial to reduce carbon emissions. This effect may happen in transport operations where the trailer is fully filled by volume before reaching its mass limit.
英国，例如北美 HGV 中的长头牵引车和可变牵引车-拖车间隙在英国的 HGV 中不存在，则英国 HGV 的潜在贡献可能不同。尽管如此，还有各种技术包可用于减少所有这些来源的阻力。它们包括简化拖拉机和拖车的形状，添加侧板和整流罩，甚至完成重新设计，从长远来看，理论上可以将阻力系数降低 42%（Delgado 等人，2017 年）。但请注意，由于形状改变而导致的有效载荷减少可能会对整体能耗产生负面影响。因此，如此大幅的减阻并不一定有利于减少碳排放。这种影响可能发生在运输操作中，即拖车在达到其质量限制之前被体积完全填满。

The average tractor weight increased over the last 20 years due to factors such as safety and comfort requirements, and the increasing stringency of pollutant emission standards (Hill et al., 2015). This trend highlights the need to reduce the mass of the tractor-trailer combination where possible in order to further increase the payload. Reducing the trailer’s unladen mass is one of the most straightforward vehicle design changes that can be made (Odhams et al., 2010). The most practical area for manufacturers to reduce trailer mass in the short-term is by using lightweight composites for trailer decking and side walls, and the design of the frame. In the long-term more radical changes are possible to significantly reduce trailer weight (Galos and Sutcliffe, 2019). For example, a composite chassis formed of carbon fibre reinforced polymer beams and a pultruded glass fibre reinforced polymer deck could drastically reduce overall trailer weight by up to 1326 kg (Galos and Sutcliffe, 2019). However, the materials are not yet affordable. In (Hill et al., 2015), the overall potential of light-weighting to reduce the emissions of heavy duty transport vehicles was examined. The results showed that it is possible to achieve mass reductions of 5% in the short-term and 17% by 2030.
由于安全性和舒适性要求以及污染物排放标准日益严格等因素，拖拉机的平均重量在过去 20 年中有所增加（Hill 等人，2015 年）。这一趋势凸显了在尽可能减少牵引车-拖车组合质量以进一步增加有效载荷的必要性。减少拖车的空载质量是可以进行的最直接的车辆设计更改之一（Odhams 等人，2010 年）。对于制造商来说，在短期内减少拖车质量的最实用领域是将轻质复合材料用于拖车甲板和侧壁，以及框架的设计。从长远来看，更激进的改变有可能显着减轻拖车的重量（Galos 和 Sutcliffe，2019 年）。例如，由碳纤维增强聚合物梁和拉挤玻璃纤维增强聚合物甲板组成的复合材料底盘可以大大减轻拖车的整体重量，最高可达 1326 公斤（Galos 和 Sutcliffe，2019 年）。然而，这些材料还不能负担得起。在 （Hill et al.， 2015） 中，研究了轻量化减少重型运输车辆排放的整体潜力。结果表明，短期内有可能实现 5% 的减重，到 2030 年实现 17% 的减重。

In (Galos et al., 2015), a study was carried out in the UK to assess the potential for improving trailer design through light-weighting. It found a particularly attractive opportunity for double-deck trailer operations. Their analysis of loaded double-deck trailers for a UK grocery fleet operator found the average number of cages transported per trailer was only 83% of the maximum allowable 75 cages, due to reaching the axle load limit. Their analysis highlights the opportunity to improve the payload capacity by light-weighting the trailer. This paper focuses on evaluating a trial of new Lightweight and Aerodynamic Double Deck (LADD) trailers developed through the Low Emissions Freight Trial (TRL).
在 （Galos et al.， 2015） 中，在英国进行了一项研究，以评估通过轻量化改进拖车设计的潜力。它为双层拖车运营发现了一个特别有吸引力的机会。他们对英国杂货车队运营商的装载双层拖车的分析发现，由于达到轴重限制，每辆拖车运输的平均笼子数量仅为最大允许的 75 个笼子的 83%。他们的分析强调了通过减轻拖车重量来提高有效载荷能力的机会。本文重点介绍了通过低排放货运试验 （TRL） 开发的新型轻型和空气动力学双层 （LADD） 拖车的试验。

During the project, 2 aerodynamic trailers, 2 lightweight trailers and 2 aerodynamic-lightweight trailers were manufactured. All of them were double-deck semi-trailers, meant for long haul transport operations. These trailers were then operated by a supermarket chain for transport operations between their distribution centres and outlets. The main project objective was to evaluate the fuel consumption of the prototype vehicles against baseline HGVs. Both the prototype and baseline HGVs were tractor semi-trailer combinations. This article shares the analysis from this project, including coast-down tests to estimate the reduction in coefficient of aerodynamic drag from the aerodynamic features and the reduction in coefficient of rolling resistance from the use of wide single tyres, instead of dual pairs, on the lightweight trailers.
在项目期间，制造了 2 辆空气动力学拖车、2 辆轻型拖车和 2 辆空气动力学轻型拖车。它们都是双层半挂车，用于长途运输作业。然后，这些拖车由一家连锁超市运营，用于其配送中心和网点之间的运输业务。项目的主要目标是根据基线 HGV 评估原型车的油耗。原型和基线 HGV 都是拖拉机半挂车组合。本文分享了该项目的分析，包括滑行测试，以估计空气动力学特性对空气动力阻力系数的降低，以及在轻型拖车上使用宽单轮胎而不是双对轮胎对滚动阻力系数的降低。

The main contributions of this article are as follows:
本文的主要贡献如下：

Estimation of coefficients of aerodynamic drag and rolling resistance of the double-deck HGVs.
双层 HGV 的空气动力阻力和滚动阻力系数的估计。

Evaluation of the double-deck HGVs for in-service drive cycles using telematics data.
使用远程信息处理数据评估用于在役驾驶循环的双层 HGV。

Model-based evaluation of the double-deck HGVs for standard drive cycles and different vehicle weights.
对标准驾驶循环和不同车辆重量的双层 HGV 进行基于模型的评估。

The in-service evaluation used telematics data, whereas the evaluation for standard drive cycles used model-based simulations with experimentally estimated coefficients of aerodynamic drag and rolling resistance. The coast-down experiments to estimate these coefficients were conducted on a test track.
在役评估使用远程信息处理数据，而标准驾驶循环的评估使用基于模型的模拟，通过实验估计空气动力阻力和滚动阻力系数。估计这些系数的滑行实验是在测试轨道上进行的。

Fig. 1. The semi-trailer aerodynamic features: boat tail, deflector and fin.
图 1. 半挂车的空气动力学特点是：船尾、导流板和鳍。

Aerodynamic and lightweight semi-trailers
空气动力学和轻型半挂车

The aerodynamic features on the aerodynamic HGVs and aerodynamic-lightweight HGVs reduced their aerodynamic drag. These features are shown in Fig. 1. The semi-trailers are 13.58 m long and 2.55 m wide. At the rear end of the trailer, there is a tapered 1.48 m long ‘boat tail’ at an angle of 4.5 deg. The boat-tailing was only applied to the sides of the trailer, as can be inferred from Fig. 1. It was not applied to the trailer top to avoid undesired loading issues, which may result in undesired transportation efficiency. Wind tunnel tests on a ¹10^th scale model (Garcia et al., 2018) showed approximately 3.4% reduction in the coefficient of aerodynamic drag due to this modification. Although a larger taper (up to 9 deg) would have been more beneficial, the angle was constrained by the necessary width of the rear doors. The front end of the trailer has a deflector and fin to prevent cross flow due to side winds. These showed approximately 2.5% and 2.4% reductions in drag, respectively, in the wind tunnel tests. Note that the type of tractor used in this work, which is shown in Fig. 3, and the scale model used in the wind tunnel tests have the same aerodynamic features, including the roof deflector, side extenders and tractor-trailer gap. Together, all three aerodynamic features reduced the aerodynamic drag by approximately 8%. The project and baseline trailers were fitted with full-length side skirts, optimised to reduce underbody flow and hence drag. The 8% drag reduction is in addition to the performance improvement from the side skirts.
空气动力学 HGV 和空气动力学轻型 HGV 的空气动力学特性降低了它们的空气动力学阻力。这些特征如图 1 所示。半挂车长 1358 m，宽 255 m。在拖车的后端，有一个 148 m 长的锥形 “船尾”，角度为 45 度。船尾部仅适用于拖车的侧面，从图 1 中可以推断出。它没有应用于拖车顶部，以避免意外的装载问题，这可能会导致意外的运输效率。1 10^比例模型（Garcia 等人，2018 年）的风洞测试表明，由于这种修改，空气动力阻力系数降低了约 34%。虽然更大的锥度（最高 9 度）会更有利，但角度受到后门必要宽度的限制。拖车的前端有一个导流板和鳍，以防止由于侧风引起的交叉流动。这些结果表明，在风洞测试中，阻力分别减少了大约 2 5% 和 24%。请注意，本工作中使用的拖拉机类型（如图 3 所示）和风洞测试中使用的比例模型具有相同的空气动力学特征，包括车顶导流板、侧延长器和拖拉机-拖车间隙。所有三种空气动力学特性共同将空气动力学阻力降低了约 8%。项目拖车和基线拖车配备了全长侧裙，经过优化以减少车身底部流动，从而减少阻力。8% 的阻力减少是侧裙性能改进的补充。

The trailer mass was reduced by using lighter materials for the chassis, lower and upper decks, doors, running gear, and for the side- walls of the semi-trailer. The light-weighting features included high strength steel rolling chassis, and composite materials for the upper and lower decks. The lightweight trailers were fitted with wide single tyres, which lowered the coefficient of rolling resistance compared to the dual pairs. The prototype light-weight trailer had a mass of 8.8 t compared to the baseline mass of 11.3 t, i.e. a reduction of 2.5 t. However, shortly after commencing transport operations, the trailer decks and side-walls developed defects. Therefore, these parts need reinforcement and this activity is ongoing. This work used the proven mass reduction of 1350 kg from the chassis. From previous research (Galos and Sutcliffe, 2019), a proposed mass reduction of 500 kg from the side-walls, 120 kg from the decks and 40 kg from the doors were also used.
通过在底盘、上下甲板、车门、行走装置和半挂车的侧壁上使用更轻的材料来减轻拖车的质量。轻量化特点包括高强度钢滚动底盘和上下甲板的复合材料。轻型拖车配备了宽大的单轮胎，与双对轮胎相比，这降低了滚动阻力系数。原型轻型拖车的质量为 88 吨，而基线质量为 113 吨，即减少了 25 吨。然而，在开始运输操作后不久，拖车甲板和侧壁出现了缺陷。因此，这些部分需要加固，并且这项活动正在进行中。这项工作使用了底盘减轻 1350 kg 的经过验证的质量。根据以前的研究（Galos 和 Sutcliffe，2019 年），还建议使用侧壁减重 500 公斤、甲板减重 120 公斤和门减重 40 公斤。

Methodology
方法论

This section describes the data collection and evaluation methods, and the types of vehicles used in each evaluation method. Telematics data from two aerodynamic HGVs and a baseline HGV were collected for a period of 5 months, while these vehicles performed their normal transport operations. This data was used to perform an in-service analysis of these vehicles to understand the benefits of the aerodynamic HGVs for their normal transport operations.
本节介绍数据收集和评估方法，以及每种评估方法中使用的车辆类型。收集了来自两辆空气动力学 HGV 和一辆基线 HGV 的远程信息处理数据，为期 5 个月，同时这些车辆执行正常的运输操作。这些数据用于对这些车辆进行在役分析，以了解空气动力学 HGV 对其正常运输操作的好处。

The analysis of telematics data has limitations arising from numerous factors, including different wind velocities, road slope profiles and route profiles. In addition, telematics data was not available for the lightweight vehicles. Therefore, model-based evaluations were also performed to analyse performance of the HGVs. This analysis was performed for the baseline HGV, aerodynamic HGV, lightweight HGV, aerodynamic-lightweight HGV, HGV with lower rolling-resistance and HGV with lower Unladen Vehicle Weight (UVW). Note that the lightweight HGVs have lower rolling-resistance and UVW. Table 1 shows the parameters of each vehicle type. The model-based evaluations were performed for six drive cycles, and they used coefficients of aerodynamic drag and rolling resistance, which were estimated using coast-down experiments conducted on a test track.
远程信息处理数据的分析受到许多因素的限制，包括不同的风速、道路坡度剖面和路线剖面。此外，轻型车辆的远程信息处理数据不可用。因此，还进行了基于模型的评估以分析 HGV 的性能。该分析针对基线 HGV、空气动力学 HGV、轻型 HGV、空气动力学轻型 HGV、滚动阻力较低的 HGV 和空载车辆重量 （UVW） 较低的 HGV。请注意，轻型 HGV 具有较低的滚动阻力和 UVW。表 1 显示了每种车辆类型的参数。基于模型的评估对 6 次驾驶循环进行了评估，他们使用了空气动力阻力和滚动阻力系数，这些系数是通过在测试跑道上进行的滑行实验来估计的。

Data collection
数据采集

This section describes data collection from the telematics system and coast-down tests. The telematics data were collected in- service, whereas the coast-down tests were performed on a test track.
本节介绍从远程信息处理系统和滑行测试中收集的数据。远程信息处理数据是在服务中收集的，而滑行测试是在测试跑道上进行的。

Telematics data
远程信息处理数据

Telematics data from two tractors, each pulling an aerodynamic double-deck semi-trailer, and from a tractor, pulling a baseline double-deck semi-trailer, were collected in-service for a period of 5 months in 2019. All three tractors were of the same model and make, ‘MB Actros 2545’ from Daimler Truck AG, and were fitted with telematics systems from Daimler Fleetboard GmbH. The
2019 年，在役 5 个月期间收集了来自两台拖拉机（每辆牵引车牵引一辆空气动力学双层半挂车）和牵引车（牵引基线双层半挂车）的远程信息处理数据。所有三台拖拉机都是相同的型号和品牌，即戴姆勒卡车公司的“MB Actros 2545”，并配备了戴姆勒 Fleetboard GmbH 的远程信息处理系统。这

Fig. 2. Satellite image of the twin-straights test track at Horiba-MIRA Ltd, UK, where the coast-down tests were performed.
图 2. 英国 Horiba-MIRA Ltd 的双直道测试跑道的卫星图像，在那里进行了滑行测试。

Fig. 3. A photograph of the instrumented baseline heavy goods vehicle.
图 3. 配备仪表的基线重型货车的照片。

Table 1
表 1

Coefficients of aerodynamic drag times frontal area (C_dA), coefficients of rolling resistance (C_r) and UVWs of different vehicle types.
不同车辆类型的空气动力阻力系数乘以正面面积 （CdA）、滚动阻力系数 （C） 和 UVW。

telematics data set included date (yyy:mm:dd), average speed (km/h), diesel used (l), transport work (t.km), distance (km), driving style, operational time (hh:mm:ss), vehicle start time (hh:mm:ss) and vehicle stop time (hh:mm:ss), at a frequency of once per day. Here, driving style is a driver performance variable out of 1000, and it depends on the acceleration and deceleration values.
远程信息处理数据集包括日期 （YYY：MM：DD）、平均速度 （km/h）、使用的柴油 （l）、运输工作 （t.km）、距离 （km）、驾驶方式、运营时间 （HH：MM：SS）、车辆启动时间 （HH：MM：SS） 和车辆停止时间 （HH：MM：SS），频率为每天一次。在这里，驾驶风格是 1000 分的驾驶员性能变量，它取决于加速和减速值。

Coast-down tests
滑行测试

Coast-down tests were conducted to estimate the coefficients of aerodynamic drag and rolling resistance of an HGV with an aerodynamic-lightweight double-deck semi-trailer and of an HGV with a baseline double-deck semi-trailer. These tests were carried out on the twin-straights test track at Horiba-MIRA Ltd, UK, shown in Fig. 2. In each direction, the horizontal track is 1.6 km long and the two straights are joined by banked loops at each end.
进行了滑行测试，以估计带有空气动力学轻量级双层半挂车的 HGV 和带有基线双层半挂车的 HGV 的空气动力阻力和滚动阻力系数。这些测试在英国 Horiba-MIRA Ltd 的双直道测试跑道上进行，如图 2 所示。在每个方向上，水平轨道长 1.6公里，两条直线在两端由倾斜的环连接起来。

Fig. 4. A typical example of the measured speed profile from one of the coast-down tests.
图 4. 滑行测试中测得的速度曲线的典型示例。

These tests had two objectives: 1) estimate the reduction in coefficient of aerodynamic drag due to the aerodynamic features of the aerodynamic trailers, and 2) estimate the reduction in coefficient of rolling resistance due to the wide single tyres on the lightweight trailers. The reduction in coefficient of aerodynamic drag is applicable for the aerodynamic HGVs and the aerodynamic-lightweight HGVs. The reduction in coefficient of rolling resistance is applicable for the lightweight HGVs and aerodynamic-lightweight HGVs.
这些测试有两个目标：1） 估计由于空气动力学拖车的空气动力学特性而导致的空气阻力系数的降低，以及 2） 估计由于轻型拖车上较宽的单轮胎而导致的滚动阻力系数降低。空气动力阻力系数的降低适用于空气动力学 HGV 和空气动力学轻型 HGV。滚动阻力系数的降低适用于轻型 HGV 和空气动力学轻型 HGV。

The HGVs were instrumented with an inertial and navigation system, ‘RT3022’, from Oxford Technical Solutions Ltd. The processing unit with a built-in inertial measurement system was installed inside the tractor cabin. The primary GPS antenna was installed on the tractor roof. Before each test, the ‘RT3022’ was initialised using the manufacturer instructions.
这些 HGV 配备了 Oxford Technical Solutions Ltd. 的惯性和导航系统“RT3022”。带有内置惯性测量系统的处理单元安装在拖拉机驾驶室内。主 GPS 天线安装在拖拉机车顶上。在每次测试之前，'RT3022' 都使用制造商的说明进行初始化。

The coast-down tests were performed with an unloaded trailer and with an almost fully loaded trailer. When loaded, the trailer was loaded with concrete blocks to a Gross Vehicle Weight (GVW) between 43 and 44 t. The GVW was measured using the weighing bridge at the test facility.
滑行测试是用空载的拖车和几乎满载的拖车进行的。装载时，拖车装载有混凝土块，车辆总重 （GVW） 在 43 至 44 吨之间。GVW 是使用测试设施的称重桥测量的。

During each test, the HGV was accelerated to a maximum speed close to 84 km/h and was allowed to coast-down. As the twin- straights test track is only 1.6 km long in each direction, it is not long enough for the HGV to coast-down from 84 km/h to standstill in one go. Therefore, when the vehicle approached the end of a straight segment, the final vehicle speed was noted. The vehicle was brought back to the start of the same straight segment with a slightly higher speed than the noted final speed from the last coast- down lap. This process was continued until the vehicle stopped. This whole process was done for both directions of travel along the twin-straights test track, i.e. North East and South West in Fig. 2. The track is very close to level with no measurable change of elevation between the two ends. Fig. 4 shows the longitudinal vehicle speed profile during one of the coast-down tests. In addition to the vehicle’s longitudinal speed, longitudinal acceleration was measured.
在每次测试期间，HGV 被加速到接近 84 公里/小时的最高速度，并被允许滑行。由于双直道测试跑道每个方向只有 1.6公里长，因此 HGV 无法一次性从 84 公里/小时滑行到静止。因此，当车辆接近直线段的终点时，会记录最终的车速。车辆被带回同一直线段的起点，速度略高于最后一个滑行圈的记录最终速度。这个过程一直持续到车辆停下来。整个过程是针对沿双直线测试轨道的两个行驶方向完成的，即图 2 中的东北和西南。轨道非常接近水平，两端之间没有可测量的高程变化。图 4 显示了其中一次滑行测试期间的纵向车速曲线。除了车辆的纵向速度外，还测量了纵向加速度。

The longitudinal equations of motion of a vehicle (Madhusudhanan et al., 2020; Hunt et al., 2011) is as follows:
车辆的纵向运动方程（Madhusudhanan et al.， 2020;Hunt et al.， 2011）的裁决如下：

 P_w(t) = ma(t)v(t)+P_a(t)+P_r(t)+P_g(t) (1)
P_w（t） = 马（t）v（t）+P_a（t）+P_r（t）+P_g（t） （1）

 1 ²

 P_a(t) = ρ_airC_dA(v(t) − v_w) v(t) (2)
P_a（t） = ρ_空气C_dA（v（t） − v_w） v（t） （2）

2

 P_r(t) = C_rmgv(t) (3)
P_r（t） = C_rmgv（t） （3）

 P_g(t) = mgsinθ(t)v(t) (4)
P_g（t） = mgsinθ（t）v（t） （4）

Here P_w is the engine power transmitted to the wheels, m is the gross vehicle mass, a is the longitudinal acceleration, v is the longitudinal speed, P_a is the power dissipated by aerodynamic drag, P_r is the power dissipated by rolling resistance, P_g is the power required to ascend the road gradient, ρ_air = 1.225 kg/m³ is the density of air, C_d is the coefficient of aerodynamic drag, A is the vehicle’s frontal area, v_w is the component of the wind speed along the South West direction in Fig. 2, C_r is the coefficient of rolling resistance, g = 9.81 m/s² is the acceleration due to gravity and θ is the road gradient. The effective mass of rotating components, driveline mechanical losses and speed dependence of rolling resistance coefficient McAuliffe and Chuang (2016), were ignored while estimating the coefficients. Although these are drawbacks of the estimation method, their effects were assumed negligible to compare two vehicles with the coefficients obtained using the estimation method used in this work.
其中 P_w 是传递到车轮的发动机功率，m 是车辆总质量，a 是纵向加速度，v 是纵向速度，P_a 是空气动力阻力耗散的功率，PR 是滚动阻力耗散的功率，P_g 是上升道路坡度所需的功率，ρ_空气 = 1225 kg/m³ 是空气密度，C_d 是空气阻力系数，A 是车辆的正面面积，v_w 是图 2 中沿西南方向的风速分量，C_r是滚动阻力系数，g = 981 m/s² 是重力加速度，θ 是道路坡度。在估计系数时，忽略了旋转部件的有效质量、传动系统机械损耗和滚动阻力系数的速度依赖性 McAuliffe 和 Chuang （2016）。尽管这些是估计方法的缺点，但假设它们的影响可以忽略不计，将两辆车与使用本研究中使用的估计方法获得的系数进行比较。

When a vehicle coasts-down on a horizontal road, P_w = 0 as the vehicle is in neutral gear and P_g = 0 as the road gradient is zero. Therefore, Eq. (1) can be simplified as follows:
当车辆在水平道路上滑行时，P_w = 0 表示车辆处于空档， P _g = 0 表示道路坡度为零。因此，方程。 （1） 可以简化如下：

 1 ²

 ma(t) = − 2ρ_airC_dA(v(t) − v_w) − C_rmg (5)
马（t） = − 2ρ_空气C_dA（v（t） − v_w） − C_rmg（5）

Estimation of the coefficient of aerodynamic drag, C_d, and the coefficient of rolling resistance, C_r, involved two steps: 1) estimation of the wind speed, v_w, and 2) estimation of the coefficients.
空气动力阻力系数 C_d 和滚动阻力系数 C_r 的估计包括两个步骤：1） 估计风速 v_w 和 2） 估计系数。

For the first step, Eq. (5) was rewritten as follows:
对于第一步，Eq. （5） 被重写如下：

 1 ²

2m
2米

 [ 1 ][ w 2 ] (7)
[ 1 ][w 2 ] （7）

 2m 1
2米1

 = CT[(v(t) − vw)2 ] (8)
= C[（v（t） − vw）2 ] （8）

1

Here C = _−ρairC_dA − C_rg is the coefficient vector. Using the model form in Eq. 8, the coefficient vector, C, can be estimated so that a linear model relating (v(t) ₋ v_w)² and a(t) can be found. This linear model fitting was used in the following optimisation problem
其中 C = _−ρairC_dA − C_rg 是系数向量。使用 Eq 中的模型形式。 8 中，可以估计系数向量 C，以便找到与 （v（t） ₋ v_w）² 和 a（t） 相关的线性模型。此线性模型拟合用于以下优化问题

C

 C (i,x)
C（i，x）

 i=1 _SW
=1_个软件

Here, x is the optimisation argument whose optimised value is the wind speed estimate, ̂v_w;C_SW(x) _∈ R² is the coefficient vector of the linear model that fits (v_SW(t) ₋ x)² and a_SW(t) as shown in Eq. (8); C_NE(x) _∈ R² is the coefficient vector of the linear model that fits (v_NE(t) ₊ x)² and a_NE(t);v_NE and v_SW are the speed measurements when the vehicle coasts-down in the North East and South West track respectively; and a_NE and a_SW are the acceleration measurements when the vehicle coasts-down in the North East and South West track respectively.
其中，x 是优化参数，其优化值是风速估计值，̂v_wC_SW（x） _∈ R² 是拟合 （v_SW（t） ₋ x）² 的线性模型的系数向量和 _SW（t） 如 Eq 所示。 （8）;C_NE（x） _∈ R² 是拟合 （v_NE（t） ₊ x）² 和 _{a NE（}t） 的线性模型的系数向量;v_NE 和 v_SW 分别是车辆在东北和西南轨道上滑行时的速度测量值;_NE 和 _SW 分别是车辆在东北和西南轨道上滑行时的加速度测量值。

The vehicle speed and acceleration measurements were sampled at 1 kHz, and a moving average filter with a window size of 200 was used to improve the signal to noise ratio.
车速和加速度测量值以 1 kHz 采样，并使用窗口尺寸为 200 的移动平均滤波器来提高信噪比。

Fig. 5 shows the v(t)− v_w versus acceleration, i.e. a(t), with zero wind speed and the estimated wind speed value. These plots are from two tests. The North East plots only use measurements when the vehicle coasted-down along the North East direction, and the South West plots only use measurements when the vehicle coasted-down along the South West direction. These plots correspond to the quadratic equation relating v(t)− v_w and a(t) in (6). Note that crosswinds can affect the coefficient of aerodynamic drag Hucho (1986). Therefore, the cost-down tests were conducted when the wind speed was minimal, given the practical constraints such as available track time. The average wind speed during these tests was 1.1 m/s with a maximum of 2.4 m/s and minimum of 0.5 m/s. Therefore, the effect of crosswind was assumed to be negligible. If this assumption is valid, and if the wind speed is therefore estimated appropriately, the North East and South West plots should overlap each other. In the right hand plot, with the estimated wind speed of − 2.4 m/s, the North East and South West plots overlap.
图 5 显示了 v（t）− v_w 与加速度（即 a（t））的关系，风速为零，并且是估计的风速值。这些图来自两个测试。东北图仅使用车辆沿东北方向滑行时的测量值，而西南图仅使用车辆沿西南方向滑行时的测量值。这些图对应于 （6） 中 v（t）− v_w 和 a（t） 相关的二次方程。请注意，侧风会影响空气动力阻力系数 Hucho （1986）。因此，考虑到可用赛道时间等实际限制，在风速最小的情况下进行了成本降低测试。这些测试期间的平均风速为 1.1 m/s，最高为 2.4 m/s，最低为 0.5 m/s。因此，假设侧风的影响可以忽略不计。如果此假设有效，并且因此对风速进行了适当的估计，则东北图和西南图应相互重叠。在右侧图中，估计风速为 − 24 m/s，东北和西南图重叠。

After estimating the wind speed, the second step was performed, i.e. estimation of the coefficients of aerodynamic drag and rolling resistance. Using the wind speed estimate from Eq. (9), the coefficients were initialised with the following values:
估计风速后，执行第二步，即估计空气动力阻力和滚动阻力系数。使用来自 Eq. （9） 中，系数使用以下值进行初始化：

m[C_NE(1,̂v_w) + C_SW(1,̂v_w)]
m[C_NE（1̂v_w） + C_SW（1̂v_w）]

 [C_dA]₀ = − 

C_NE(2,̂v_w) + C_SW(2,̂v_w)
C_NE（2̂v_w） + C_SW（2̂v_w）

 [C_r]₀ = − 

Here, [C_dA]₀ is the initial estimate of the coefficient of aerodynamic drag times frontal area, and [C_r]₀ is the initial estimate of the coefficient of rolling resistance. The product, C_dA, was estimated as a single quantity as it is difficult to estimate the effective frontal area due to the complicated shape of a tractor semi-trailer combination. Based on the range of values of these coefficients from literature, constraints, 5m²_⩽C_dA⩽12m² and 0.002⩽C_r⩽0.009, were set. These allowable ranges were set as follows:
其中，[C_dA]₀ 是空气动力阻力系数乘以正面面积的初始估计值，[C_r]₀ 是滚动阻力系数的初始估计值。产品 C_dA 被估计为单个数量，因为由于牵引车半挂车组合的形状复杂，很难估计有效正面面积。根据文献中这些系数的值范围，设置了 5m²_⩽C_dA⩽12m² 和 0002⩽C_r⩽0009 的约束条件。这些允许的范围设置如下：

 Pz⩽b where (12)
Pz⩽b，其中 （12）

 ⎡ ⎤

 1 0

 P = ⎢⎢⎣−01 01 ⎥⎥⎦ (13)
P = ⎢⎢⎣−01 01 ⎥⎥⎦ （13）

 0 − 1

 ⎡ ⎤

12

 b = ⎢⎢⎣ 0−.0095 ⎥⎥⎦and (14)
b = ⎢⎢⎣ 0−0095 ⎥⎥⎦和 （14）

Fig. 5. Vehicle’s v(t)− v_w versus a(t) without and with wind speed correction with the wind speed estimate of − 2.4 m/s.
图 5. 车辆的 v）− v_w 与 a） 无风速校正和有风速校正，风速估计值为 − 24 m/s。

 z = [C_dA C_r ]^T(15)
z = [C_dA C_r ]^T （15）

The coefficients, ̂z. were found by minimising the difference between the measured time, t_m, the vehicle took to coast-down from v₀ to standstill on the test track and the time estimate, ̂t, for the vehicle to coast-down from v₀ to standstill with the optimisation argument, z
系数 ̂z。通过最小化测量的时间 tm （车辆在测试轨道上从 V0 滑行到静止）与车辆从 V0 滑行到静止的时间估计值 ̂t （使用优化参数 z） 来找到.

 ̂t(z,v₀,̂v_w,m)
̂t（z，v₀̂v_w，m） 

 v(0) = v₀(18)
v（0） = v₀ （18）

The optimisation uses the initial estimates from Eqs. (10) and (11), and the constraints in Eq. (12). It was run until the relative changes in all elements of the optimisaiton argument were less than the step tolerance of 10^{− 10}. Fig. 6 shows the measured speed profile from one of the tests and the modelled speed profile using Eq. (6) with the estimated coefficients of aerodynamic drag and rolling resistance, and wind speed.
优化使用 Eqs 的初始估计值。 （10） 和 （11） 以及方程中的约束。 （12）。它一直运行，直到 optimisaiton 参数的所有元素的相对变化小于 10^{− 10} 的步长容差。 图 6 显示了其中一项测试测得的速度曲线和使用方程建模的速度曲线。 （6） 用估计的气动阻力和滚动阻力系数，以及风速。

The coast-down test procedure, described above, was employed for an aerodynamic-lightweight HGV and a baseline HGV. For each vehicle, 3 tests were conducted on the North East test track and 3 on the South West test track. Table 2 shows the estimated coefficients of aerodynamic drag and rolling resistance from the coast-down tests.
上述滑行测试程序用于空气动力学轻型 HGV 和基线 HGV。对于每辆车，在东北测试跑道上进行了 3 次测试，在西南测试跑道上进行了 3 次测试。表 2 显示了滑行测试的空气动力阻力和滚动阻力的估计系数。

From Table 2, it is seen that the aerodynamic features reduced the coefficient of aerodynamic drag by approximately 7.2% and the wide single tyres on the lightweight trailer reduced the coefficient of rolling resistance by approximately 10%. Considering the model assumptions regarding the effective mass of rotating components, driveline mechanical losses, crosswind and speed dependence of coefficient of rolling resistance, the estimated coefficients are sufficiently reliable that the relative results of one vehicle configuration to another should be reliable. In addition, the reduction in aerodynamic drag is comparable to the 8% reduction, observed in the scaled down wind tunnel tests, mentioned in Section 2
从表 2 中可以看出，空气动力学特性使空气阻力系数降低了约 72%，轻型拖车上的宽单轮胎将滚动阻力系数降低了约 10%。考虑到有关旋转部件有效质量、传动系统机械损失、侧风和滚动阻力系数的速度依赖性的模型假设，估计的系数足够可靠，一种车辆配置与另一种车辆配置的相对结果应该是可靠的。此外，空气动力阻力的减少与第 2 节中提到的缩小风洞测试中观察到的 8% 减少相当.

Evaluation of the HGVs for transport performance and cost
重型货车的运输性能和成本评估

This section shares the evaluation results of different vehicle types for different drive cycles. First, in-service telematics data was used to compare 2 HGVs with aerodynamic trailers with a baseline vehicle. Next, the fuel consumption models were used to evaluate an aerodynamic trailer, a lightweight trailer, an aerodynamic-lightweight trailer and the baseline trailer. The drive cycles used in the model-based evaluation are long haul, regional delivery, urban delivery and city centre drive cycles from the Low Carbon Vehicle Partnership (LowCVP) (Robinson and Eastlake, 2016), heavy heavy-duty diesel truck (HHDDT) cruise drive cycle (DieselNet), and motorway cruising at 84 km/h. These drive cycles represent different driving scenarios an HGV may encounter. The LowCVP long haul and HHDDT cruise drive cycles represent typical scenarios an HGV may encounter while performing a long haul transport operation. The LowCVP urban delivery and city centre drive cycles represent typical scenarios in an urban setting with more acceleration and deceleration events than the long haul drive cycles. The HHDDT drive cycle is based on the HHDDT chassis dynamometer test,
本节分享了不同车型在不同驾驶循环下的评估结果。首先，使用在役远程信息处理数据将 2 辆带有空气动力学拖车的 HGV 与基线车辆进行比较。接下来，油耗模型用于评估空气动力学拖车、轻型拖车、空气动力学-轻型拖车和基线拖车。基于模型的评估中使用的驾驶循环是低碳汽车伙伴关系 （LowCVP） 的长途、区域交付、城市交付和市中心驾驶循环（Robinson 和 Eastlake，2016 年）、重型重型柴油卡车 （HHDDT） 巡航驾驶循环 （DieselNet） 和高速公路巡航 84 公里/小时。这些驾驶循环代表 HGV 可能遇到的不同驾驶场景。LowCVP 长途和 HHDDT 巡航驾驶循环代表了 HGV 在执行长途运输操作时可能遇到的典型情况。LowCVP 城市配送和市中心驾驶循环代表了城市环境中的典型场景，与长途驾驶循环相比，加速和减速事件更多。HHDDT 驾驶循环基于 HHDDT 底盘测功机测试，

Fig. 6. Measured speed from one of the coast-down tests and modelled speed using the estimated coefficients and wind speed.
图 6. 从其中一项滑行测试中测量的速度，并使用估计的系数和风速对速度进行建模。

Table 2
表 2

Results of the coast-down tests of an aerodynamic-lightweight (AL) HGV and a baseline (BL) HGV. SD stands for standard deviation.
空气动力学轻型 （AL） HGV 和基线 （BL） HGV 的滑行测试结果。SD 代表标准差。

developed by the California Air Resources Board and West Virginia University.
由加州空气资源委员会和西弗吉尼亚大学开发。

Telematics data
远程信息处理数据

A statistical analysis was performed to understand whether the trailer type, i.e. baseline or aerodynamic, has a statistically significant effect on fuel consumption. This analysis was only performed for the aerodynamic and baseline vehicles. After discarding unwanted data sets such as those with daily distance less than 100 km, which account for 0.5% of the total vehicle kilometres, a multiple linear regression model of the following form was fitted to the telematics data:
进行了统计分析以了解拖车类型，即基线或空气动力学，是否对油耗有统计学上的显着影响。该分析仅针对空气动力学和基线车辆进行。在丢弃不需要的数据集（例如每日距离小于 100 公里的数据集，占车辆总公里数的 0 5%）后，将以下形式的多元线性回归模型拟合到远程信息处理数据中：

 f = β₀ +β₁m+β₂v+β₃s+β₄T (19)
f = β₀ +β₁m+β₂v+β₃s+β₄T（19）

Here, f is the fuel consumption in l/km, β₀ to β₄ are the model coefficients, m is the daily average vehicle mass in tonne, v is the daily average vehicle speed in km/h and s is a driver performance variable out of 1000, which is calculated by the telematics provider and depends on acceleration and deceleration values. If s = 1000, the driver performance is maximum, i.e. a smooth driver. In (19), m,v and s are numerical predictor variables, whereas the trailer type, T, is a categorical predictor variable. Outputs from the analysis include the coefficients expressing the change in fuel consumption for unit changes in the predictor variables, the estimated standard error (SE) in these coefficients, and the p-value expressing the probability that the null-hypothesis related to this statistic can be rejected. In this analysis, the null-hypothesis was rejected (i.e. statistical significance was assumed) for a p-value less than 0.05.
其中，f 是以 l/km 为单位的油耗，β₀ 到 β₄ 是模型系数，m是日平均车辆质量（以吨为单位），v是日平均车速（以 km/h 为单位）和 s 是 1000 个驾驶员性能变量，由远程信息处理提供商计算，取决于加速和减速值。如果 s = 1000，则驱动程序性能最高，即平稳的驱动程序。在 （19） 中，mv和 s 是数值预测变量，而拖车类型 T 是分类预测变量。分析的输出包括表示预测变量中单位变化的燃料消耗变化的系数、这些系数中的估计标准误差 （SE） 以及表示与此统计量相关的原假设可以被拒绝的概率的 p 值。在此分析中，如果 p 值小于 005，则零假设被拒绝（即假设具有统计显著性）。

Results of the model fit for the predictor variables are shown in Table 3. The results show that fuel consumption increases with increasing vehicle weight, reducing speed and lower driver performance, with high statistical significance. The effect of trailer type is also statistically significant with a p-value of 0.00016. The negative sign in the coefficient of trailer type denotes a reduction in fuel consumption for the aerodynamic trailer compared with the baseline trailer.
预测变量的模型拟合结果如表 3 所示。结果表明，燃料消耗随着车辆重量的增加而增加，速度降低和驾驶员性能降低，具有很高的统计显著性。拖车类型的影响在统计意义上也很显著，p 值为 000016。拖车类型系数中的负号表示与基线拖车相比，空气动力学拖车的油耗降低。

Fig. 7 illustrates predictions by the model, showing the effect of the four predictor variables for given values of the other three variables (as indicated below the sub-plots). The red dashed lines are the 95 % confidence bounds on the model. Of note is the counter- intuitive result that the fuel consumption decreases with increasing average speed, which is mostly caused by the lower traffic congestion with higher average speed Nasir et al. (2014), Zhang et al. (2011). The increase in fuel consumption with lower driver performance is caused by frequent or harsh acceleration or deceleration events Meseguer et al. (2015, 2017). The analysis show that the aerodynamic HGV’s fuel consumption is approximately 2.5% lower for the operating conditions in Fig. 7 (i.e. m = 28.3 t, v = 59.9 km/h and s = 737).
图 7 说明了模型的预测，显示了四个预测变量对其他三个变量的给定值的影响（如子图下方所示）。红色虚线是模型的 95% 置信边界。值得注意的是，燃料消耗随着平均速度的增加而降低，这主要是由于较低的交通拥堵和较高的平均速度引起的 Nasir et al. （2014）， Zhang et al. （2011）。Meseguer 等人（2015 年、2017 年）频繁或剧烈的加速或减速事件导致油耗增加和驾驶员表现不佳。分析表明，在图 7 中的运行条件下（即 m = 283 t，v = 599 km/h 和 s = 737），空气动力学 HGV 的油耗降低了约 2 5%。

This analysis of telematics data has limitations arising from numerous factors, including different wind velocities, road slope profiles and route profiles. Therefore, model-based evaluations were also performed to analyse performance of the HGVs.
这种远程信息处理数据分析由于许多因素而存在局限性，包括不同的风速、道路坡度剖面和路线剖面。因此，还进行了基于模型的评估以分析 HGV 的性能。

Model-based evaluation
基于模型的评估

The model used to evaluate fuel consumption was based on previous research on fuel consumption modelling (Hunt et al., 2011; Madhusudhanan et al., 2020). For all the vehicle types that were manufactured during this project, i.e. aerodynamic HGV, lightweight HGV, aerodynamic-lightweight HGV and baseline HGV, fuel consumption models were created with the coefficients of aerodynamic drag and rolling resistance from the coast-down tests. The lightweight HGVs were fitted with lower rolling resistance tyres. To
用于评估燃料消耗的模型基于先前对燃料消耗建模的研究（Hunt 等人，2011 年;Madhusudhanan et al.， 2020）。对于本项目期间制造的所有车辆类型，即空气动力学 HGV、轻型 HGV、空气动力学轻型 HGV 和基线 HGV，使用滑行测试中的空气动力阻力和滚动阻力系数创建了油耗模型。轻型 HGV 配备了较低的滚动阻力轮胎。自

Table 3
表 3

Results of the multiple linear regression model fit using the telematics data.
多元线性回归模型的结果使用远程信息处理数据进行拟合。

Fig. 7. Predictor slice plots showing best-fit model predictions and 95% confidence limits.Y-axis: fuel consumption [l/km]. Subplots: Average vehicle mass [t], Average speed [km/h], Driving style [-], Trailer type (B = Baseline, A = Aerodynamic).
图 7. 显示最佳拟合模型预测和 95% 置信限的预测变量切片图。Y 轴：油耗 [/km]。子图：平均车辆质量 [t]、平均速度 [km/h]、驾驶方式 [-]、拖车类型（B = 基线，A = 空气动力学）。

differentiate the effects of lower rolling resistance and light-weighting, two more vehicle types, i.e. one with lower rolling resistance and the other with lower Unladen Vehicle Weight (UVW), were evaluated. Table 1 shows the coefficients and UVWs of different vehicles.
区分较低滚动阻力和轻量化的影响，评估了另外两种车辆类型，即一种具有较低的滚动阻力，另一种具有较低的空载车辆重量 （UVW）。 表 1 显示了不同车辆的系数和 UVW。

The drive cycles used in the model-based evaluation, and their details are shown in Table 4. The ‘aerodynamic factor’ in Table 4 is the normalised ratio of energy required to overcome aerodynamic drag versus the total energy required for the drive cycle. The aerodynamic factor was normalised using the ratio for motorway cruising at 84 km/h. Consequently, a score of 0 represents a low speed drive cycle in which aerodynamic drag is insignificant, whereas 100% represents steady speed operation at 84 km/h on a motorway. The model-based evaluation used two GVW values: 1) 30.5 t, which was the average GVW from the telematics data of three HGVs from a period of 5 months, and 2) 44 t, which is the fully loaded case.
表 4 显示了基于模型的评估中使用的驱动循环及其详细信息。表 4 中的“空气动力学系数” 是克服空气阻力所需能量与驾驶循环所需总能量的标准化比率。空气动力学系数使用 84 公里/小时的高速公路巡航比率进行标准化。因此，分数 0 表示空气阻力不大的低速行驶循环，而 100% 表示在高速公路上以 84 公里/小时的速度稳定运行。基于模型的评估使用了两个 GVW 值：1） 305 t，这是 5 个月内三辆 HGV 的远程信息处理数据的平均 GVW，以及 2） 44 t，这是满载情况。

Fig. 8a–d show the percentage reduction in fuel consumption per t.km transport work of different vehicle configurations for the two GVW values. Here, t.km transport work is the work done to transport 1000 kg of goods for a distance of 1 km. The Aerodynamic HGV legend in Fig. 8a shows that the maximum fuel consumption benefit for the aerodynamic HGV is 4.7%, when it cruises on motorways at 84 km/h (aerodynamic factor of 100%). The second and third highest fuel consumption benefits, 3.7% and 3.0%, are for the HHDDT Cruise (a long haul drive cycle) and LowCVP Long Haul drive cycles, respectively. Clearly, the fuel consumption benefits would be greater if the cruising speed was higher. The benefit from aerodynamic features is the lowest for the LowCVP City Centre drive cycle due to frequent accelerations and decelerations, and lower speed values in the drive cycle.
图 8a-d 显示了两个 GVW 值下不同车辆配置每次 t.km 运输作业的油耗降低百分比。在这里，t.km 运输工作是将 1000 公斤货物运输 1 公里的距离所做的工作。图 8 a 中的空气动力学 HGV 图例显示，当空气动力学 HGV 以 84 公里/小时的速度在高速公路上巡航时（空气动力学系数为 100%）时，空气动力学 HGV 的最大油耗优势为 4% 7%。第二和第三高的油耗优势，37% 和 30%，分别适用于 HHDDT Cruise（长途驾驶循环）和 LowCVP Long Haul 驾驶循环。显然，如果巡航速度更高，油耗优势会更大。由于频繁的加速和减速以及驾驶循环中的较低速度值，空气动力学功能的好处对于 LowCVP City Centre 驾驶循环来说是最低的。

The fuel consumption benefit for the Lightweight HGV in Fig. 8a is between 17.2% (LowCVP City Centre drive cycle) and 18.5% (Motorway Cruising at 84 km/h). The benefit of light-weighting depends on the mass reduction, which was assumed as 2010 kg in Section 2 with a proven mass reduction of 1350 kg from the chassis and a proposed mass reduction of 660 kg from the body. The results in Fig. 8c show that the wide single tyres with lower rolling resistance offer 1.9% (LowCVP City Centre drive cycle) to 3.5% (Motorway Cruising at 84 km/h) fuel consumption benefit, whereas the lower UVW offers 15.5% fuel consumption benefit. The ‘Lower Rolling Resistance and UVW’ cases in Fig. 8c and d are the same as the ‘Lightweight HGV’ cases in Fig. 8a and b, respectively.
图 8 a 中轻型 HGV 的油耗优势在 17.2%（LowCVP City Centre 驾驶循环）和 18.5%（高速公路巡航速度 84 公里/小时）之间。轻量化的好处取决于质量减轻，在第 2 节中假设减轻了 2010 公斤 ，经证实，底盘减轻了 1350 公斤，建议从车身减轻 660 公斤。图 8 c 中的结果表明，具有较低滚动阻力的宽单轮胎可提供 1.9%（LowCVP City Centre 驾驶循环）至 3.5%（高速公路巡航速度为 84 km/h）的油耗优势，而较低的 UVW 提供 15.5% 的油耗优势。图 8 c 和 d 中的“较低滚动阻力和 UVW”情况分别与图 8a 和 b 中的“轻型 HGV”情况相同。

The Aerodynamic-Lightweight HGV has the most fuel consumption benefit in Fig. 8a as it has aerodynamic and light-weighting features, and lower rolling resistance tyres. The fuel consumption benefit is the lowest for the LowCVP City Centre drive cycle at around 17.5% and is the highest for Motorway Cruising at 84 km/h at around 22.4%.
空气动力学轻量化 HGV 在图 8 a 中具有最大的油耗优势，因为它具有空气动力学和轻量化特性，以及较低的滚动阻力轮胎。LowCVP City Centre 驾驶循环的油耗优势最低，约为 17.5%，高速公路巡航最高，为 84 公里/小时，约为 22.4%。

Comparing the results in Fig. 8a and b, and those in in Fig. 8c and d, indicates that the fuel consumption benefit per transport work decreases as the GVW increases.
将图 8a 和 b 中的结果与图 8 c 和 d 中的结果进行比较，表明每次运输工作的燃料消耗收益随着 GVW 的增加而减少。

Table 4
表 4

Drive cycles used in the model-based evaluation of different HGVs.
用于不同 HGV 的基于模型的评估的驾驶循环。

Fig. 8. Fuel consumption benefit per t.km transport work [%] for different HGV configurations compared to the baseline.
图 8. 与基线相比，不同 HGV 配置的每 t.km 运输工作的油耗降低 [%]。

Fig. 9a and b show the fuel consumption per transport work [l/100t.km] of different vehicle configurations for the two GVW values. Contrary to Fig. 8a and b, Fig. 9a and b show that the fuel consumption per transport work [l/100t.km] decreases as the GVW increases. As shown in Fig. 9b, the lowest fuel consumption per transport work is for the fully loaded (44 t) Aerodynamic-Lightweight HGV.
图 9 a 和 b 显示了两个 GVW 值下不同车辆配置的每次运输作业的油耗 [l/100t.km]。与图 8a 和 b 相反，图 9a 和 b 显示，每次运输作业的燃料消耗 [l/100t.km] 随着 GVW 的增加而降低。如图 9b 所示，每次运输工作的最低油耗是满载 （44 t） 空气动力学轻型卡车。

Considering an average round trip distance of 240 km and 361 such trips in year (data from the project partner), and with a baseline fuel economy of 3.65 km/l (calculated from the telematics data), the baseline HGV needs approximately 23737 l of diesel per year. With a Net Calorific Value (NCV) of 35.99 MJ/l and Well-To-Wheel (WTW) equivalent carbon emission of 91.87 g/MJ for diesel UK- Government (2019), MacLeay et al. (2010), the baseline HGV’s equivalent carbon emissions in a year is approximately 78.5 t. As the project partner’s fleet consists of 724 double-deck semi-trailers, with 3% fuel benefit from the aerodynamic features in the long haul drive cycle, if the aerodynamic modifications were applied to all the fleet trailers, the equivalent carbon emission savings will be approximately 1705 t per year. Note that most double-deck trailers are operated for long haul transport operations. Similarly, with 21% fuel benefit from the aerodynamic-lightweight HGV for the long haul drive cycle, if the aerodynamic and light-weighting modifications were applied to all the fleet trailers, the equivalent carbon emission savings will be approximately 11935 t per year.
考虑到平均往返距离为 240 公里，每年有 361 次这样的行程（数据来自项目合作伙伴），基线燃油经济性为 365公里/升（根据远程信息处理数据计算），基线卡车每年需要大约 23737 升柴油。英国政府柴油净热值 （NCV） 为 3599 MJ/l，油井到车轮等效碳排放量为 9187 g/MJ（2019 年），MacLeay 等人（2010 年）认为 HGV 一年的等效碳排放量约为 785 吨。由于项目合作伙伴的车队由 724 辆双层半挂车组成，在长途驾驶循环中，空气动力学特性使 3% 的燃料受益，如果对所有车队拖车进行空气动力学改造，相当于每年可减少约 1705 吨的碳排放。请注意，大多数双层拖车用于长途运输操作。同样，在长途驾驶循环中，空气动力学轻量化卡车可节省 21% 的燃料，如果对所有车队拖车进行空气动力学和轻量化改造，等效每年可节省约 11935 吨碳排放。

Conclusions
结论

This article evaluated the effect of aerodynamic and lightweight interventions to double-deck semi-trailers on fuel consumption of HGV transport operations. The evaluation used in-service telematics data from 5 months, and predictions using simulation models. For the aerodynamic improvements, there is reasonable agreement between the estimated fuel consumption benefit from the model based analysis and from the telematics based analysis. The coefficients of aerodynamic drag and rolling resistance of different types of vehicle were estimated from the coast-down tests. Compared to a baseline trailer, the coast-down tests showed that the aerodynamic features reduced the coefficient of aerodynamic drag by approximately 7.2% and that the wide single tyres on the lightweight trailers reduced
本文评估了双层半挂车的空气动力学和轻量化干预对 HGV 运输作业燃料消耗的影响。评估使用了 5 个月的在役远程信息处理数据，并使用仿真模型进行预测。对于空气动力学改进，基于模型的分析和基于远程信息处理的分析的估计油耗收益之间存在合理的一致性。通过滑行试验估计不同类型车辆的空气动力阻力和滚动阻力系数。与基线拖车相比，滑行测试表明，空气动力学特性使空气阻力系数降低了约7.2%，而轻型拖车上的宽单轮胎降低了

Fig. 9. Fuel consumption per transport work [l/100t.km] for different HGV configurations.
图 9. 不同 HGV 配置的 每次运输作业的油耗 [/100t.km]。

the coefficient of rolling resistance by approximately 10%.
滚动阻力系数降低约 10%。

The estimated coefficients were used in simulation model based evaluations to predict fuel consumption benefits. For a GVW of
估计的系数用于基于仿真模型的评估，以预测油耗效益。对于 GVW

30.5 tonne, the average GVW from the telematics data, the aerodynamic trailer reduces the HGV’s fuel consumption by approximately 4.7% while cruising on UK motorways at 84 km/h and by approximately 3% on the LowCVP Long Haul drive cycle. The lightweight trailer reduces the HGV’s fuel consumption by approximately 18.5% while cruising on motorways at 84 km/h and by approximately 17.7% on the LowCVP Long Haul drive cycle. The low rolling resistance tyres in the lightweight trailer offer approximately 3.5% fuel consumption benefit while cruising on motorways at 84 km/h and by approximately 2.5% on the LowCVP Long Haul drive cycle. The aerodynamic-lightweight trailer reduces the HGV’s fuel consumption by approximately 22.4% while cruising on motorways at 84 km/ h and by approximately 20.2% on the LowCVP Long Haul drive cycle. In addition, evaluations were performed for the LowCVP City Centre drive cycle, LowCVP regional delivery drive cycle, LowCVP urban delivery drive cycle and for the HHDDT cruise drive cycle. All three HGV configurations give the lowest fuel consumption benefit for the LowCVP City Centre drive cycle. The fuel consumption per transport work decreases as the GVW increases. The lowest fuel consumption per transport work is for the fully loaded (44 t) Aerodynamic-Lightweight HGV.
305 吨，来自远程信息处理数据的平均 GVW，空气动力学拖车在英国高速公路上以 4 公里/小时的速度巡航时将 HGV 的油耗降低了约 74%，在 LowCVP 长途驾驶循环中降低了约 3%。轻型拖车在高速公路上以 84 公里/小时的速度巡航时，可将 HGV 的油耗降低约 18 5%，在 LowCVP 长途驾驶循环中可降低约 17 7%。轻型拖车中的低滚动阻力轮胎在高速公路上以 84 公里/小时的速度巡航时提供约 3.5% 的油耗优势，在 LowCVP 长途驾驶循环中提供约 2.5% 的油耗优势。空气动力学轻型拖车在高速公路上以 22 公里/小时的速度巡航时将 HGV 的油耗降低约 44%，在 LowCVP 长途驾驶循环中降低约 20 2%。此外，还对 LowCVP City Centre 驾驶循环、LowCVP 区域交付驾驶循环、LowCVP 城市交付驾驶循环和 HHDDT 邮轮驾驶循环进行了评估。所有三种 HGV 配置都为 LowCVP City Centre 驾驶循环提供了最低的油耗优势。每次运输工作的燃料消耗量随着 GVW 的增加而降低。每次运输工作的最低油耗是满载 （44 t） 空气动力学轻型卡车。

From the 5 months of telematics data from two aerodynamic HGVs and a baseline HGV, statistical significance with a p-value of 0.00016 was found for the effect of trailer type on fuel consumption. The results also showed statistical significance for higher fuel consumption with increasing vehicle weight, reducing speed and lower driver performance. The analysis show that the aerodynamic HGV’s fuel consumption is approximately 2.5% lower than the baseline, which is similar to the model based results with mid-range aerodynamic factors.
从来自两辆空气动力学 HGV 和一辆基线 HGV 的 5 个月远程信息处理数据中，发现拖车类型对油耗影响的统计显着性为 0 00016。结果还显示，随着车辆重量的增加、速度的降低和驾驶员性能的降低，油耗的增加具有统计学意义。分析表明，空气动力学 HGV 的油耗比基线低约 2-5%，这与具有中等空气动力学因素的基于模型的结果相似。

From a policy and practice point of view, the results from this research imply that aerodynamic improvements of a semi-trailer can reduce fuel consumption for long-haul transport operations, whereas lightweighting a semi-trailer can reduce fuel consumption significantly in both long- and short-haul transport operations. As these improvements do not have significant barrier to implementation, which is the case with electricifation of HGVs and autonomous driving technologies like truck platooning, fleet operators can employ these improvements to reduce their carbon emissions.
从政策和实践的角度来看，这项研究的结果表明，半挂车的空气动力学改进可以减少长途运输作业的燃料消耗，而减轻半挂车的轻量化可以显著降低长途和短途运输作业的燃料消耗。由于这些改进对实施没有重大障碍，例如卡车电动化和卡车列队行驶等自动驾驶技术，车队运营商可以利用这些改进来减少碳排放。

Acknowledgements
确认

The authors would like to thank Clifford Smith and Caroline Milnes from Tesco Plc, Duncan Johnson and Andy Richardson from Lawrence David Ltd, Jimmy Dorrian from SDC Trailers Ltd, Ryan Kingston from Aerodyne Global Ltd, Gordon Molyneux from GB Fleetcare Ltd, Antonio Argentieri from Mercedes-Benz Trucks UK Ltd, and Paul Lewis and Andrew Marriot from Horiba MIRA Ltd, for their support during this project.
作者要感谢 Tesco Plc 的 Clifford Smith 和 Caroline Milnes、Lawrence David Ltd 的 Duncan Johnson 和 Andy Richardson、SDC Trailers Ltd 的 Jimmy Dorrian、Aerodyne Global Ltd 的 Ryan Kingston、GB Fleetcare Ltd 的 Gordon Molyneux、Mercedes-Benz Trucks UK Ltd 的 Antonio Argentieri 以及 Horiba MIRA Ltd 的 Paul Lewis 和 Andrew Marriot。 感谢他们在这个项目期间的支持。

Data used in drafting of this article is available at https://doi.org/10.17863/CAM.63690by
本文起草中使用的数据可在 https://doi.org/10.17863/CAM.63690by.

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