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Engine downsizing is potentially one of the most effective strategies being explored to improve fuel economy. A main problem of downsizing using a turbocharger is the small range of stable functioning of the turbocharger centrifugal compressor at high boost pressures. Several stabilization techniques were studied to increase the compressor operating range without sacrificing the compressor efficiency. The paper presents an experimental study of one of these techniques, the axial variable inlet guide vanes (VIGV). Test rigs were put up to conduct two different experiments. The first was to study the effect of pre- rotation generated by VIGVs on the overall compressor performance and the second to determine the pressure loss through the VIGVs and to analyze the flow downstream the VIGV system using LDA (laser Doppler Anemometry) measurement.

This paper presents an experimental study of a water injection (WI) application where water fog is added in the intake of a common rail High-Speed Direct Injection (HSDI) automobile Diesel engine in order to reduce pollutant emissions Nitrogen Oxides and Particulate Matter (NOx and PM) for future emissions standards. Also studied are the physical parameters of the engine (in-cylinder pressure, air inlet temperature, air mass flow, specific fuel consumption etc). The results are compared with those obtained with low-pressure dry Exhaust Gas Recirculation (LP EGR) on the same engine. Tests performed with the water injection system show that a much better NOx / PM trade-off (reduced NOx emission levels at constant PM emission levels) is obtained than with EGR especially at points of high engine loads. In addition, tests are performed with EGR in parallel with water injection to investigate the reduction of NOx emissions while potentially reducing water consumption.

One of the main advantage of a hybrid thermal-electric vehicle is that the internal combustion engine (ICE) can be shut down when not needed anymore (Stop&Start system, propulsion with full-electric mode), thus reducing fuel consumption. But this use of the ICE impacts its thermal behavior because of a lack of heat source and thermal losses. Furthermore, the ICE is sometimes used with higher load in order to charge the batteries that increases the total heating power produced by the combustion. Therefore, the simulation of hybrid vehicles becomes really interesting to evaluate the effect of different control strategies (energy repartition between the engine and the electric motor) on the fuel consumption. However, in most of actual hybrid vehicles simulation tools, for calculation speed reasons, the thermal phenomena are either not taken into account, or their calculation is not based on physical equations (empirical formulas). Their predictive capability is then limited.

The tightening restrictions, in terms of fuel consumption, have pushed the vehicle manufacturers and equipment suppliers into searching for innovative ways to reduce the carbon dioxide emissions. Along with the ameliorations added to the engine itself, additional systems are grafted to the engine in order to keep up with the ever-changing laws. Isolating the impact on the fuel consumption of an added system, by on board testing, is a complicated task. In this case, using simulation modeling allows the reduction of delays related to prototyping and testing. This paper presents modeling of various thermal systems in a vehicle and their interactions to evaluate the fuel consumption using AMESim software. As means to reduce the CPU cost of the model (calculation time), without decreasing its predictability, engine modeling has been done by two steps: high frequency model and mean value model.

The impact of the drag coefficient of a vehicle on its fuel consumption is very important. This paper will treat a proposition to reduce the drag coefficient via a reduction of the underhood opening area. The coastdown technique is adopted to find the drag coefficient. Three post-processing methods are then compared. Although, reducing the underhood opening ameliorates the drag coefficient, it influences as well the thermal performance of the cooling system, causing a possible overheating of the engine. For this reason, the impact of the underhood opening area on the cooling air speed is studied in detail as well. The purpose of these tests is to draw some variation laws that govern the response of a vehicle to a reduction in the underhood opening.