Special Issue "Recent Advances in Vehicle Aerodynamics"

A special issue of Energies (ISSN 1996-1073).

Deadline for manuscript submissions: closed (31 October 2019).

Special Issue Editor

Prof. Lennart Löfdahl
E-Mail Website
Guest Editor
Department of Mechanics and Maritime Sciences, Chalmers University of Technology, Gothenburg 41296, Sweden
Interests: vehicle aerodynamics; thermal management; CFD for automotive applications; turbulence modeling; experimental fluid dynamics; wind tunnels; 3D separation

Special Issue Information

Dear Colleagues,

Vehicle aerodynamics will play a decisive role in advancing energy-efficient and safe vehicles for future requirements of a climate-friendly environment. The interaction between aerodynamics and thermal management will undoubtedly constitute one essential aspect in the paradigm shift into fully electric vehicles. Furthermore, the functioning of sensors for safety issues and autonoumus driving is fundamental and places high demands on the requirements of the soiling areas on vehicles. Hence, the search for energy-efficient and safe vehicles will be fundamental in twenty-first century transport research.

The objective of this Special Issue is to contribute to the development and optimization of vehicle aerodynamics. This will be done through enhanced scientific and multi-disciplinary knowledge transfer, in which an interaction among different areas within the subject will be encouraged. The focus will be on improved energy-efficiency and safety by taking into account the shifting landscape of electrical propulsion and autonoumus driving.

We therefore invite papers on fundamental and innovative technical developments; reviews; case studies; and numerical, analytical, as well as assessment papers from different disciplines in the subject, that are relevant to the development of sustainable vehicles.

Prof. Lennart Löfdahl
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All papers will be peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Energies is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1800 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • rotating wheels, wheel-house flows, and ventilation drag
  • active flow control for drag reduction
  • three-dimensional separation
  • near and far wake flows
  • soiling and contamination
  • high-speed stability
  • vehicle interaction, overtaking, and platooning
  • high-performance and race-car aerodynamics
  • wind tunnel development and certifications, WLTP
  • real world flows simulations
  • thermal management, cooling drag
  • brake cooling
  • battery box climatization, engine encapsulation, and HVAC

Published Papers (6 papers)

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Research

Open AccessArticle
Influence of Side Spoilers on the Aerodynamic Properties of a Sports Car
Energies 2019, 12(24), 4697; https://doi.org/10.3390/en12244697 (registering DOI) - 10 Dec 2019
Abstract
This paper discusses the capabilities of side spoilers to improve the aerodynamic properties of a sports car exposed to a non-zero yaw angle flow. In such conditions, the aerodynamic drag and lift both increase with the introduction of a side force and a [...] Read more.
This paper discusses the capabilities of side spoilers to improve the aerodynamic properties of a sports car exposed to a non-zero yaw angle flow. In such conditions, the aerodynamic drag and lift both increase with the introduction of a side force and a yawing moment, which contribute to the decrease of the car’s handling properties and force the car to change its driving path. Elements mounted on the side of the car make it possible to obtain an asymmetric aerodynamic load distribution and generate additional forces that can be used to counter these effects. The performance of the side spoilers was analyzed at yaw angles ranging from 0° to 15° using the results of numerical calculations. It was established that the side spoilers made it possible to generate at low yaw angles aerodynamic forces that exceeded those caused by a crosswind. Full article
(This article belongs to the Special Issue Recent Advances in Vehicle Aerodynamics)
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Open AccessArticle
Flow Angularity Investigations in an Automotive Slotted Wall Wind Tunnel
Energies 2019, 12(23), 4575; https://doi.org/10.3390/en12234575 - 30 Nov 2019
Abstract
The Volvo Cars aerodynamic wind tunnel has had a vortical flow angularity pattern in the test section since its original commissioning in 1986. The vortical flow nature persisted after an upgrade in 2006, when the fan was replaced and a moving ground system [...] Read more.
The Volvo Cars aerodynamic wind tunnel has had a vortical flow angularity pattern in the test section since its original commissioning in 1986. The vortical flow nature persisted after an upgrade in 2006, when the fan was replaced and a moving ground system was introduced. It has been hypothesized that the cause for this flow angularity pattern was leakages around the heat exchanger installed in the settling chamber. The present paper tests this hypothesis by measuring the flow angularity in the test section before and after sealing the leakages. The findings show that the leakage path around the heat exchanger does not influence the flow angularity, and that the current pattern is different compared to the commissioning after the upgrade. This prompted an investigation of the influence from the turbulence screens, which were changed after the upgrade commissioning. These investigations indicate that the probable cause of the vortical flow angularity pattern is residual swirl from the fan. Force measurements on a reference car with and without extra induced flow angularity show that the flow angles measured in the tunnel for regular operation are most likely small enough to not have a significant effect on the measured aerodynamic forces. Full article
(This article belongs to the Special Issue Recent Advances in Vehicle Aerodynamics)
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Open AccessArticle
A Coupled 1D–3D Numerical Method for Buoyancy-Driven Heat Transfer in a Generic Engine Bay
Energies 2019, 12(21), 4156; https://doi.org/10.3390/en12214156 - 31 Oct 2019
Abstract
Energy efficient vehicles are essential for a sustainable society and all car manufacturers are working on improved energy efficiency in their fleets. In this process, an optimization of aerodynamics and thermal management is most essential. The objective of this work is to improve [...] Read more.
Energy efficient vehicles are essential for a sustainable society and all car manufacturers are working on improved energy efficiency in their fleets. In this process, an optimization of aerodynamics and thermal management is most essential. The objective of this work is to improve the energy efficiency using encapsulated heat generating units by focusing on predicting temperature distribution inside an engine bay. The overall objective is to make an estimate of the generated heat inside an encapsulation and consecutively use this heat for climatization purposes. The study presents a detailed numerical procedure for predicting buoyancy-driven flow and resulting natural convection inside a simplified vehicle underhood during thermal soak and cool-down events. The procedure employs a direct coupling of one-dimensional and three-dimensional methods to carry out transient one-dimensional thermal analysis in the engine solids synchronized with sequences of steady-state three-dimensional simulations of the fluid flow. The boundary heat transfer coefficients and averaged fluid temperatures in the boundary cells, computed in the three-dimensional fluid flow model, are provided as input data to the one-dimensional analysis to compute the resulting surface temperatures which are then fed back as updated boundary conditions in the flow simulation. The computed temperatures of the simplified engine and the exhaust manifolds during the thermal soak and cool-down period are in favorable agreement with experimental measurements. The present study illustrates the capabilities of the coupled thermal-flow methodology to conduct accurate and fast computations of buoyancy-driven heat transfer. The methodology can be potentially applied to design and analysis of multiple demand vehicle thermal management systems in hybrid and electrical vehicles. Full article
(This article belongs to the Special Issue Recent Advances in Vehicle Aerodynamics)
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Open AccessArticle
Investigation of Wheelhouse Flow Interaction and the Influence of Lateral Wheel Displacement
Energies 2019, 12(17), 3340; https://doi.org/10.3390/en12173340 - 29 Aug 2019
Abstract
The aim of this research was to improve the understanding of the complex flow features found around a wheel and wheelhouse and to examine how the lateral displacement of the wheel affects these features and the production of exhibited pressures and forces. A [...] Read more.
The aim of this research was to improve the understanding of the complex flow features found around a wheel and wheelhouse and to examine how the lateral displacement of the wheel affects these features and the production of exhibited pressures and forces. A bespoke rotating wheel rig and accompanying wheelhouse with a fully-pressure-tapped wheel arch was designed and manufactured at Loughborough University. Wind tunnel tests were performed where force and pressure measurements and Particle Image Velocimetry (PIV) data were obtained. The experimental data was used to validate unsteady CFD predictions where a k- ω SST Improved Delayed Detached Eddy Simulation (IDDES) turbulence model was used in STAR-CCM+ (10.04.009, Siemens). The CFD showed good agreement with all trends of the experimental results providing a validated numerical methodology. For both methodologies, a lower amount of wheelhouse drag was found generated when the wheel was rotating. However, the CFD showed that whilst this was the case, total configuration drag had increased. This was attributed to an increase of the wheel and axle drag, illustrated by the change in separation over the wheel itself when located within a wheelhouse and so overcompensating the reduction in body and stand drag. Differences in vortex locations when comparing to previously-attained results were due to differences in housing geometry, such as blockage in the cavity or housing dimensions. Experimental and computational results showed that up until a 10 mm displacement outboard of the housing, overall drag decreased. The reduction in housing drag was credited to a reduction in the size of outboard longitudinal vortex structures. This led to the lateral width of the shear layer across the housing side being narrower. Overall, this study identified that there were potential benefits to be gained when offsetting a wheel outboard of the longitudinal edge of a model housing. Full article
(This article belongs to the Special Issue Recent Advances in Vehicle Aerodynamics)
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Open AccessArticle
Evaluation of the Multiple Reference Frame Approach for the Modelling of an Axial Cooling Fan
Energies 2019, 12(15), 2934; https://doi.org/10.3390/en12152934 - 31 Jul 2019
Abstract
The modelling of rotating parts, such as axial fans, is one of the main challenges of current CFD simulations of industrial applications. Different methods are available, but the most commonly used is the multiple reference frame (MRF) method. This paper investigates how different [...] Read more.
The modelling of rotating parts, such as axial fans, is one of the main challenges of current CFD simulations of industrial applications. Different methods are available, but the most commonly used is the multiple reference frame (MRF) method. This paper investigates how different flow properties, such as temperature, pressure and velocity, develop when passing through the MRF domain. The results are compared to the more physical rigid body motion (RBM) approach. It is found that the MRF method transports the upstream properties with the streamlines of the relative velocity from the upstream to the downstream interface. This leads to a non-physical rotation by an angle that is dependent on the length of the domain and the ratio between axial and tangential velocity in the MRF region. The temperature field is more affected than the flow field, since wake structures from upstream obstacles are destroyed due to the wake of the blades. Downstream structures affect the flow in the upstream region by an increase in static pressure, which causes the streamlines in the MRF zone to slow down. Depending on the size of the obstacle, this can cause substantial distortions in the upstream and downstream flow field. Full article
(This article belongs to the Special Issue Recent Advances in Vehicle Aerodynamics)
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Open AccessArticle
Analysis of Subjective Qualitative Judgement of Passenger Vehicle High Speed Drivability due to Aerodynamics
Energies 2019, 12(14), 2839; https://doi.org/10.3390/en12142839 - 23 Jul 2019
Abstract
The flow created by the shape of a vehicle and by environmental conditions, such as cross-winds, will influence the dynamics of a vehicle. The objective of this paper is to correlate the driver’s subjective judgement of drivability with quantities which are measurable during [...] Read more.
The flow created by the shape of a vehicle and by environmental conditions, such as cross-winds, will influence the dynamics of a vehicle. The objective of this paper is to correlate the driver’s subjective judgement of drivability with quantities which are measurable during a vehicle test. For this purpose, a sedan vehicle, fitted with different aerodynamic external devices that create disturbances in the flow field, were assessed on a test track. These configurations intend to result in substandard straight line drivability. The aerodynamic devices investigated are an inverted wing, an inverted wing with an asymmetric flat plate and an asymmetric air curtain attached under the bumper. The devices generate more lift and asymmetric forces resulting in increased vehicle sensitivity to external disturbances. Pairs of configurations with and without bumper side-kicks are also tested. The side-kicks create a defined flow separation which helps to stabilize the flow and increase drivability. Plots of mean and standard deviation and ride diagram of lateral acceleration, yaw velocity, steering angle and steering torque are used to understand vehicle behaviour for the different configurations. Ride diagrams are used to visualize vehicle excitations with transient events separated from the stationary signal. The range of the measured quantities for understanding the drivability is not predicted in advance and it turns out that the error margins of the measurements are smaller than the measurement uncertainty of the Inertia Measurement Unit. Although the outcome lacks the ability to objectively quantify subjective judgements, it provides a useful qualitative assessment of the problem as the trends agree well with the subjective judgement of the driver. Full article
(This article belongs to the Special Issue Recent Advances in Vehicle Aerodynamics)
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