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The high performance brake systems of today are usually in a delicate balance - walking the fine line between being overpowered by some of the most potent powertrains, some of the grippiest tires, and some of the most demanding race tracks that the automotive world has ever seen - and saddling the vehicle with excess kilograms of unsprung mass with oversized brakes, forcing significant compromises in drivability with oversized tires and wheels. Brake system design for high performance vehicles has often relied on a very deep understanding of friction material performance (friction, wear, and compressibility) in race track conditions, with sufficient knowledge to enable this razor’s edge design.

As part of the launch of the refrigerant R-1234yf there were a number of studies done regarding the ignition behavior of this new refrigerant in passenger cars. These tests were conducted by a number of automobile manufacturers, component suppliers, and the refrigerant supplier under laboratory conditions at the component and vehicle level. In November 2009 the international automotive industry concluded that the R-1234yf can be used safely in automotive air conditioning systems. Further tests were conducted by different automobile manufacturers, suppliers, and the refrigerant supplier under various laboratory and vehicle operation conditions means hot surfaces in the engine compartment. A number of vehicle manufactures have conducted full vehicle crash tests.

The description of subjectively perceived acoustical comfort inside vehicle compartments is a complex challenge. On the one hand, it depends on physically measurable events like acoustical stimuli with a defined sound pressure level and frequency distribution. On the other hand, it is also strongly dependent on further factors like the customer's individual expectations, the previously made experiences and other contextual influences. Furthermore, many different driving conditions have to be considered for a customer-related assessment of driving comfort. In this paper, the mechanisms of acoustical comfort inside vehicle compartments are described on basis of various measurements, listening tests and qualitative assessments. The acoustical properties of driving noises at various driving conditions were taken into account as well as room-acoustical parameters of vehicle interiors and factors of speech communication between passengers.

This paper will compare systematically coaxial and non-coaxial internal heat exchanger types on the component and the system level as applied to R1234yf mobile air conditioning (MAC) systems. Pressure drop, heat transfer rate, effectiveness, and efficiency ratio of the Internal Heat Exchanger (IHX) are compared on the component level for the different heat exchanger types. At the system level, a MAC system optimized for efficiency as well as evaporator cooling capacity is used to assess these different internal heat exchanger types. System level factors that will be discussed include IHX heat transfer rate, pressure drop, compressor efficiency, compressor discharge temperatures, and the impact of these factors on the efficiency and capacity of the MAC system. This paper also describes the test bench used for the system level tests and the testing procedure applied.

High performance engines required in contemporary vehicles are causing underhood components to operate under hostile temperature environments. Aerodynamic styling and the addition of new components to the engine compartment further add to the problem by decreasing the volume of underhood cooling air flow. The addition of engine compartment coverings required to meet environmental noise reduction standards further restrict and debilitate air flow cooling. The above conditions demand that the analysis of air flow patterns and heat transfer phenomena under the hood be an essential part of early systems design of new engines, engine compartment components, and underhood component packaging. A numerical approach to calculate cooling air flow velocity and temperature distribution of the air and engine compartment components is utilized. Air flow is calculated using a finite volume Computational Fluid Dynamics code on a 220,000 cell representation of the flow domain.

This paper describes the design process of a complete HVAC module using computational fluid dynamics (CFD). CFD gives a detailed insight on the flow characteristics of HVAC components even in early design stages. Due to a close coupling with CAD/CAE systems the number of prototypes, costs, and development time can be reduced. Optimised air duct designs lead to reduced pressure losses, and turbulence levels, that consequently decrease flow induced noise. Simultaneously the air distribution of the duct outlets is uniformed. Thermal analysis gives information about the heat transfer and hot/cold air mixing process inside the HVAC module.

The purpose of this study is to develop and demonstrate the techniques needed to perform a computational analysis of a windshield de-icing problem. A numerical model of a simplified test vehicle configuration has been built which includes the passenger compartment air, the windshield and the ice/water layer. A transient analysis was performed for conditions for which cold room test data is available. The results of the numerical simulation show very reasonable agreement with the test data.

This paper presents an approach to numerically simulate greenhouse windnoise. The term “greenhouse windnoise” here describes the sound transferred to the interior through the glass panels of a series vehicle. Different panels, e.g. the windshield or sideglass, are contributing to the overall noise level. Attached parts as mirrors or wipers are affecting the flow around the vehicle and thus the pressure fluctuations which are acting as loads onto the panels. Especially the wiper influence and the effect of different wiper positions onto the windshield contribution is examined and set in context with the overall noise levels and other contributors. In addition, the effect of different flow yaw angles on the windnoise level in general and the wiper contributions in particular are demonstrated. As computational aeroacoustics requires accurate, highly resolved simulation of transient and compressible flow, a Lattice-Boltzmann approach is used.