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High-frequency pressure probes were used to map the airflow around a full-scale truck during on-road testing and around a model-scale truck during wind tunnel testing. Several configurations were tested during each type of testing. Results are presented for on-road ‘pass-by’ tests and detail velocity and coefficient of pressure variation alongside the truck at different heights. The wind tunnel data are results of flow mapping about a 10% scale model and show the velocity and coefficient of pressure distribution under and around the model truck for different configurations.

Hydrogen Internal Combustion Engine (ICE) vehicles using a traditional ICE that has been modified to use hydrogen fuel are an important mid-term technology on the path to the hydrogen economy. Hydrogen-powered ICEs that can run on pure hydrogen or a blend of hydrogen and compressed natural gas (CNG) are a way of addressing the widespread lack of hydrogen fuelling infrastructure in the near term. Hydrogen-powered ICEs have operating advantages as all weather conditions performances, no warm-up, no cold-start issues and being more fuel efficient than conventional spark-ignition engines. The Wankel engine is one of the best ICE to be converted to run hydrogen. The paper presents some details of an initial investigation of the CAD and CAE modeling of a novel design where two jet ignition devices per rotor are replacing the traditional two spark plugs for a faster and more complete combustion.

As computational methodologies become more integrated into industrial vehicle pre-development processes the potential for high transient vehicle thermal simulations is evident. This can also been seen in conjunction with the strong rise in computing power, which ultimately has supported many automotive manufactures in attempting non-steady simulation conditions. The following investigation aims at exploring an efficient means of utilizing the new rise in computing resources by resolving high time-dependent boundary conditions through a series of averaging methodologies. Through understanding the sensitivities associated with dynamic component temperature changes, optimised boundary conditions can be implemented to dampen irrelevant input frequencies whilst maintaining thermally critical velocity gradients.

The paper presents experimental analysis of the airflow around the differential center housing of a rear drive full-scale passenger car. The study included investigation of local airflow total and static pressure, as well as surface flow visualization. Estimation of the local airflow velocity is based on the measured pressure coefficients. The experiments were carried out at different test facilities: in a climatic wind tunnel, in a full-scale wind tunnel and on-road. Influence of side wind was modeled by the yawing of the car in the full-scale wind tunnel. The results show the asymmetrical structure of the flow in both, vertical and horizontal planes. Estimated longitudinal relative local velocity decreases from maximum Vr ≈ 0.4 at the lower surface of the center housing, to about Vr ≈ 0 above the upper surface. Side wind increases airflow velocity around the center housing within the investigated yaw range ± 20°

Compressed natural gas (CNG) is an attractive, alternative fuel for spark-ignited (SI), internal combustion (IC) engines due to its high octane rating, and low energy-specific CO2 emissions compared with gasoline. Directly-injected (DI) CNG in SI engines has the potential to dramatically decrease vehicles’ carbon emissions; however, optimization of DI CNG fueling systems requires a thorough understanding of the behavior of CNG jets in an engine environment. This paper therefore presents an experimental and modeling study of DI gaseous jets, using methane as a surrogate for CNG. Experiments are conducted in a non-reacting, constant volume chamber (CVC) using prototype injector hardware at conditions relevant to modern DI engines. The schlieren imaging technique is employed to investigate how the extent of methane jets is impacted by changing thermodynamic conditions in the fuel rail and chamber.

This paper relates to the design and development of a multi-modal UAV capable of aerial flight and underwater propulsion. A novel hybrid propulsion system has been manufactured and tested. Consisting of folding blades, the propeller has been optimized for propulsion both in air and water. The critical water to air transition phase is achieved by an additional impulsive thruster powered by a C02 cartridge. To decrease the drag in underwater cruise and reduce the potential damage when the vehicle impacts the water, a morphing wing has been developed. This consists of foam-carbon fiber lay-up constructed wings in a variable sweep configuration. The actuation of the sweep is achieved by linear servos mounted on the sleeve shaped spar. An integrated prototype is constructed, using an unconventional, anhedral horizontal stabilizers to allow clearance for the morphing wing.

A small-scale aeroacoustic wind tunnel has been designed and built to investigate tonal cavity noise in the frequency range applicable to passenger vehicles; 1 - 16 kHz. The tunnel is required for testing associated with an investigation into tonal cavity noise on passenger-vehicle wing mirrors. It was designed to operate in the low subsonic speed range (60 - 140 km/h) with a nozzle exit cross-sectional area of 0.02 m2 and a 4:1 aspect ratio. The design was intended to achieve a smooth, quiet flow facility. In this paper the design process is summarised and the factors leading to particular design decisions are detailed. An initial evaluation has shown that only minimal changes are required to achieve very smooth, even flow at the nozzle exit at all required test speeds. The acoustic design needs further work as there is a significant amount of flow noise at the nozzle exit between 1 and 13 kHz.

Flow control over aerodynamic shapes in order to achieve performance enhancements has been a lively research area for last two decades. Synthetic Jet Actuators (SJAs) are devices able to interact actively with the flow around their hosting structure by providing ejection and suction of fluid from the enclosed cavity containing a piezo-electric oscillating membrane through dedicated orifices. The research presented in this paper concerns the implementation of zero-net-mass-flux SJAs airflow control system on a NACA0015, low aspect ratio wing section prototype. Two arrays with each 10 custom-made SJAs, installed at 10% and 65% of the chord length, make up the actuation system. The sensing system consists of eleven acoustic pressure transducers distributed in the wing upper surface and on the flap, an accelerometer placed in proximity of the wing c.g. and a six-axis force balance for integral load measurement.

High pressure ratio (PR) compressed natural gas (CNG) jets are studied using optical diagnostics under quiescent but realistic spark-ignited (SI) engine conditions. CNG jets were issued impulsively from a bespoke direct injector. Observations into the delivery characteristics for a large pressure ratio (PR) range were carried out (8.3

Significant research has been made on traditional pre-mixed charge Spark-Ignition Natural-Gas engines which have seen widespread usage across the automotive sector. Many researchers including those in industry are now exploring the Direct-Injection concept for Natural-Gas Spark-Ignition engines. Direct-Injection has significant performance benefits over port-fuel injection, primarily due to increased volumetric efficiency as a result of injecting the fuel after intake valve closure. This could lead to enhanced driving performance over port-fuel injection comparable to gasoline engines. Furthermore, Direct-Injection with increased compression ratio in conjunction with downsizing concepts has the potential to increase thermal efficiency while exhibiting significantly lower CO2 emissions. Advanced combustion strategies like stratified mixture combustion has been widely studied for gasoline and proven to increase the low load thermal efficiency over homogeneous stoichiometric combustion.

The function of a rear view mirror is a determining factor in its shape - resulting in a flat rear mirrored face. The resulting bluff body generates unsteady base pressures which generate unsteady forces, leading to movement of the mirror surface and potential image blurring. The objective of this paper was to experimentally determine the fluctuating base pressure on a standard and modified mirror. Half a full-size vehicle was utilised, fixed to the side wall of a wind tunnel. A dynamically responsive multi channel pressure system was used to record the pressures. The modification to the mirror consisted of a series of extensions to the mirror rim, to see if this method would attenuate the fluctuating base pressures. It was found that increasing the length of the extension changed the pressure pattern across the face, and the over all magnitude of the fluctuations reduced with increasing length of extension. It was recommended to further the work via phase measurements.

Exhaust heat recovery systems are used to make use of otherwise wasted heat from a car engine. The purpose of exhaust heat recovery systems is to reduce the fuel consumption of the car and consequently reduce CO2 emissions. The unique system design described herein utilises thermoelectric generators (TEGs) and heat pipes with its key advantage being it is a passive solid state design. The use of these components creates a few design constraints. For example, both the TEGs and heat pipes have operating temperature limitations. In this paper, a naphthalene heat pipe preheat exchanger is proposed to deal with this problem. Exhaust conditions measured from a representative spark ignition engine were used in a numerical simulation to predict the performance of the exhaust heat recovery system. If 8 modules are used and the engine is producing 8kW of mechanical power, the system is predicted to produce 53.75W of electrical power.

Vortices formed around the A-pillar region dictates the pressure distribution on the side panels of a passenger vehicle and also can lead to aerodynamic noise generation. This paper compares the suitability of various turbulence models in simulating the flow behind a vehicle A-pillar region under laboratory operating conditions. Commercial software's (FLUENT and SWIFT) were used to compare the performance of various turbulence models. In FLUENT, a simplified vehicle model with slanted A-pillar geometry was generated using GAMBIT and in SWIFT, the simplified vehicle model was generated using Fame Hybrid. Computational Fluid Dynamics (CFD) simulations were carried out using FLUENT under steady state conditions using various turbulence models (k-, k- Realize, k- RNG, k- and Spalart Allamaras). In SWIFT, k-, A-RSM and HTM2 turbulence models were used for the steady state simulations. Investigations were carried out at velocities of 60, 100 and 140km/h and at 0-degree yaw angle.

At the rear of the vehicle an end acoustic silencer is attached to the exhaust system. This is primarily to reduce noise emissions for the benefit of passengers and bystanders. Due to the location of the end acoustic silencer conventional thermal protection methods (heat shields) through experimental means can not only be difficult to incorporate but also can be an inefficient and costly experience. Hence simulation methods may improve the development process by introducing methods of optimization in early phase vehicle design. A previous publication (Part 1) described a methodology of improving the surface temperatures prediction of general exhaust configurations. It was found in this initial study that simulation results for silencer configurations exhibited significant discrepancies in comparison to experimental data.

This paper is the first of two papers that address the simulation and effects of turbulence on surface vehicle aerodynamics. This, the first paper, focuses on the characteristics of the turbulent flow field encountered by a road vehicle. The natural wind environment is usually unsteady but is almost universally replaced by a smooth flow in both wind tunnel and computational domains. In this paper, the characteristics of turbulence in the relative-velocity co-ordinate system of a moving ground vehicle are reviewed, drawing on work from Wind Engineering experience. Data are provided on typical turbulence levels, probability density functions and velocity spectra to which vehicles are exposed. The focus is on atmospheric turbulence, however the transient flow field from the wakes of other road vehicles and roadside objects are also considered.

A pressure-based technique has been developed for the purpose of radiator cooling airflow measurement. The technique was effectively utilised to quantify the local time-averaged air velocity through radiator cores in a small wind tunnel. The pressure difference indicated by the technique was found to be a function of the normal component of the air velocity. This paper describes the development and use of the technique which is compact, robust and non-intrusive. By applying this technique, the airflow distribution across the radiator face has been measured for a complete vehicle in an aerodynamic wind tunnel and in an environmental chamber. Results are compared for the different test environments. The influence of airflow distribution on the Specific Dissipation (a parameter used for evaluating radiator cooling performance) is examined and results for propeller-based methods and pressure-based methods are compared.

Wind tunnels provide a convenient, repeatable method of assessing vehicle engine cooling, yet important draw-backs are the lack of a moving ground and rotating wheels, blockage constraints and, in some tunnels, the inability to simulate ambient temperatures. A series of on-road and wind-tunnel experiments has been conducted to validate a process for evaluating vehicle cooling system performance in a high blockage aerodynamic wind tunnel with a fixed ground simulation. Airflow through the vehicle front air intake was measured via a series of pressure taps and the wind-tunnel velocity was adjusted to match the corresponding pressures found during the road tests. In order to cope with the inability to simulate ambient temperatures, the technique of Specific Dissipation (SD) was used (which has previously been shown to overcome this problem).

A KIA Soul was instrumented to measure the relative velocity (magnitude and yaw angle) at the front of the vehicle and in-cabin sound at a location close to the side glass near the A-pillar vortex impingement. Tests were conducted at a proving ground under a range of conditions from low wind conditions (~3 m/s) to moderate (7-8 m/s) wind speeds. For any given set of atmospheric conditions the velocity and sound data at any given position on the proving ground were noted to be very repeatable, indicating that the local wakes dominated the "turbulent" velocity field. Testing was also conducted in an aeroacoustic wind tunnel in smooth flow and with a number of novel turbulence generating methods. The resulting sounds were analyzed to study the modulation at frequencies likely to result in fluctuation strength type noise.