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A computer code for predicting cooling air flow through the radiator and the condenser has been developed. The Reynolds-averaged Navier-Stokes equations, together with the porous flow model for the radiator and the condenser, were solved to simulate front end air flow and the engine compartment flow simultaneously. These transport equations were discretized based on a finite-volume method in a transformed domain. The computational results for a simplified engine compartment showed overall flow information, such as the cooling air flow through the radiator and the condenser, the effects of an air dam, and the effects of fresh air vents near the top of the radiator and the condenser. Comparison of the available experimental data with the analysis showed excellent prediction of the cooling air flow through the radiator and the condenser.

A new and unique facility has been developed at the Turbulent Shear Flows Laboratory at Michigan State University for the study of automotive cooling fans. Performance data can be acquired for a variety of fan and component geometries using this facility. Additionally, detailed velocity measurements can be made in the wake of the fan. This paper describes the details of the facility with examples of the data that can be acquired.

Aqua-ammonia absorption refrigeration cycle and R-134a Vapor jet-ejector refrigeration cycle for automotive air-conditioning were studied and analyzed. Thermally activated refrigeration cycles would utilize combustion engine exhaust gas or engine coolant to supply heat to the generator. For the absorption system, the thermodynamic cycle was analyzed and pressures, temperatures, concentrations, enthalpies, and mass flow rates at every point were computed based on input parameters simulate practical operating conditions of vehicles. Then, heat addition to the generator, heat removal rates from absorber, condenser, and rectifying unit, and total rejection heat transfer area were all calculated. For the jet-ejector system, the optimum ejector vapor mass ratio based on similar input parameters was found by solving diffuser's conservation equations of continuity, momentum, energy, and flow through primary ejector nozzle simultaneously.

Cooling system is one of the important systems of an engine to maintain the optimum coolant temperature across engine and its components. Analysis of cooling system at initial phase of product development will help in optimum design of the system and there by achieving better performance of engine. For this purpose the traditional method followed is to run several bench tests and to analyze the engine performance and repeat the bench tests for validating any design changes. This results in increased lead time of engine development and overall cost. To reduce the lead time as well as reduce the overall cost, 1D (one dimension) simulation tools place a major role. Simulation of engine cooling system with special kind of engine coolant water jacket is challenging. It is difficult to achieve the simulation results close to bench test due to complexity of the system.

This paper discusses the sensitivity of key parameters that are used as an input into engine cooling system simulation model that affect the coolant temperature and required airflow calculations. In simulation, these parameters are obtained either from calculations of other programs such as a combustion program or from measured engine test data and are typically assumed to be constant. Tests and measurements from vehicle tests indicate that these parameters always vary affecting the final predicted coolant temperature. The sensitivity on few selected parameters such as the ambient pressure, temperature, humidity, coolant properties among others were studied. Results discussed in this paper quantify the effect of each of these parameters on required airflow and advise which parameters must be tightly controlled to improve the robustness of the simulation model and the accuracy of predictions.

The low noise and linear sound level characteristics of passenger vehicles are receiving increased scrutiny from automotive journalists. A linear noise level rise with increasing engine rpm is the first basic aspect of insuring an acceptable vehicle interior engine noise sound quality. In a typical case of structural response to engine vibration input, interior noise begins to rise with rpm, remains constant or even drops as the engine continues to accelerate, and then exhibits a noise period corresponding to the structure's natural frequency. Frequently this nonlinearity is bothersome to the customer. During the development process, Chrysler's Dodge and Plymouth Neon exhibited just such a nonlinear rise in noise level, heard within the passenger compartment, when the vehicle was accelerated through 4200 rpm.

Cooling fan performance: pressure rise, flow rate, shaft power have been acquired. The control variables for these measurements include the fan rprn and the relative immersion of the fan into the shroud. In addition tuft visualizations and hot-wire anemometry have been used to visualize and measure the velocity field in the wake of the fan. The velocity measurements have been processed to provide phase averaged mean and RMS fluctuation levels. The mean values have been differentiated to provide the phase averaged streamwise vorticity magnitudes. The data are used to gain an understanding of the fluid mechanical attributes of the flow field, as well as to provide experimental results for comparison with computational investigations.

Environmental issues have significantly impacted automotive operations worldwide. Countries are continuing to ratchet down their allowable emissions and to remain competitive, all industries must take Life Cycle Management (LCM) and implement it into everyday practice. Economic competitiveness as a part of economic development is central to the nation's social and financial well-being. America must catch-up to the rest of the world in how it views government and industry relationships as well as how to focus costs within the corporate structure. The adversarial relationships between government and industry must give way to stronger partnerships. For this concept to succeed a long term view of problems must be made by a corporation and both short and long term actions taken to resolve these problems. Industry must help create the market for recycled goods and must “walk the talk” by using recycled goods where possible.

A global thermal model of a vehicle powertrain is used to quantify how different engine design and powertrain calibration strategies influence the performance of a vehicle heating system. Each strategy is evaluated on its ability to improve the warm-up and heat rejection characteristics of a small-displacement, spark-ignition engine while minimizing any adverse effect on fuel consumption or emissions. An energy audit analysis shows that the two strategies having the greatest impact on heating system performance are advancing the spark and forcing the transmission to operate in a lower gear. Changes in head mass, exhaust port diameter, and coolant flow rate influence the coolant warm-up rate but have relatively little effect on steady state heat transfer at the heater core.

Component operating temperatures affect both the reliability and performance of automotive alternators. It is desirable to keep the rectifier bridge and regulator temperatures below 175 C because of the semiconductors contained in this area. At temperatures greater than this, expected lifespans have been observed to decay exponentially [1]. The air flow field surrounding an alternator and component temperature fields were investigated with Computational Fluid Dynamics (CFD) simulations. The objectives of the simulations were to examine the velocity field for the flow passage and the temperature fields for the components. Design proposals have been made to improve the air flow and to reduce the operating temperature. An initial investigation was performed by setting an alternator in a test configuration and applying the appropriate heat generation for each component. The high temperatures in the alternator components occurred in the stator and the rectifier.

Vehicle development teams find it challenging to predict what their Heating, Ventilation and Air-Conditioning (HVAC) module performance will be for cold ambient (∼ -20 deg. C) test cycles such as defrost and cabin warm-up before the car is built. This uncertainty in predictions comes from varying engine heat rejection to coolant due to cold cylinder wall temperatures, calibration changes and degraded performance of various components within the cooling system such as the coolant pump owing to higher viscosity of the coolant. Measuring engine heat rejection at cold ambient is extremely difficult as the engine warms up as soon as it is fired. Multiple measurement points require long lead time to soak to the cold target temperature. It is a common practice to adjust engine calibration parameters to warm up coolant as fast as possible for an adequate defrost and cabin warm-up performance.

A new 3.5 liter, 60 degrees V6 engine has been designed specifically for Chrysler's 1993 MY line of mid-size sedans - Dodge Intrepid, Eagle Vision, Chrysler Concorde and New Yorker. This new engine features many new components for enchanced performance. The cylinder head has a single overhead cam, four valve-per - cylinder design. The intake system is a cross-flow design equipped with dual throttle bodies, and the manifold also incorporates a vacuum operated tuning valve that increases the mid-range torque of the engine. A windage tray is used on every engine to reduce drag on the rotating components within the crankcase. Dual knock sensors (one per cylinder bank) are used to take advantage of the aggressive spark advance and high compression ratio. The engine also utilizes a plastic, helical, water pump impeller that contributes to low parasitic power losses. The engine incorporates many components and features to ensure durability.

This paper discusses a streamlined approach for characterizing the heat flows from the combustion chamber to the engine coolant, engine oil circuit and the ambient. The approach in this paper uses a built-in flow and heat transfer solver in the CAD model of the engine to derive heat transfer coefficients for the coolant-block interface, oil-block interface and the block-ambient interface. These coefficients take into account the changing boundary conditions of flow rate, temperatures, and combustion heat to help characterize the complex thermal interactions between each of these sub-systems during the warm-up process. This information is fed into a larger system model of the engine to get a more accurate prediction of the engine warm-up and the effect of various fuel economy improvement strategies being evaluated. One of the key benefits shared in this paper is the practicality of the process that can be replicated on every production vehicle simulation model.

The Charge Air Cooler (CAC) is designed to cool the charge air after being boosted by the Turbocharger. In order to maintain the optimum temperature and to further improve the charge air density entering to the engine the CAC is used. This makes the combustion more efficient and better engine performance and fuel economy. The performance of the CAC is highly affected by the plumbing lines which transport the compressed charge air from turbocharger to the intake manifold of the Engine. It consists of tube, hose, duct and resonator. Designing the optimum CAC plumbing lines with lesser pressure drop is the major requirement of the CAC system considering the complex packaging. In such scenarios, one-dimensional (1D) simulation is a good way to compute the pressure drop for faster and economical solution.

During the automotive brake system design and development process, a large number of performance characteristics must be comprehended, assessed, and balanced against each other and, at times, competing performance objectives for the vehicle under development. One area in brake development that is critical to customer acceptance due to its impact on a vehicle's perceived quality is brake pedal feel. While a number of papers have focused on the specification, quantification and modeling of brake pedal feel and the various subsystem characteristics that affect it, few papers have focused specifically on brake corner hoses and their effect on pedal feel, in particular, during race-track conditions. Specifically, the effects of brake hose fluid consumption pedal travel and brake system response is not well comprehended during the brake development process.