The Numerical Modeling Of Heat Transfer In Engine

The performance of power, economics and emission of engine are basically decided by the process of the combustion and heat transfer. With the increasing of the engine power per liter, the thermal load of engine parts increasingly become the key issue in the development of the engine, which must be considered by engine designers. Thereby, the research of the numerical modeling of heat transfer in engine and the development of temperature measure system are very important to designing of the self-made engine. Because the inside work processing of engine is very complex, and the influence factor are numerous, the heat transfer and thermal load inside engine are primarily investigated by means of experiment. In this paper, the temperature measuring system was designed and built up with closely conjugation of the actually development project of the ChangAn Corp., Ltd. The parameters detected by the system included engine's speed, torque, temperature of in-water, out-water and oil and mass flow rate of cooling water, the absolute pressure of in-water and out-water, the temperature and pressure and the volume flow rate of air, as well as temperature of cylinder block and cylinder head at 40 channels simultaneously. The temperature measuring system of the engine comprises the acquisition modules (ADAM modules), the communication module (ADAM 4520) and the expert acquisition software, which can detect and handle with data signal under industrial environment. The original signals from variety of sensors were converted into digital signals by ADAM modules, and then were transferred into computer through the RS485 communicator to be handled. The system features high efficiency, simple system construction, good credibility and stability. The main technical specifications and functions of the temperature measuring system of the engine are as follows:* The measuring accuracy of temperature within ± 1 ℃.* The measuring accuracy of water flow rate within ±1.5%.* The measuring accuracy of motor speed within ±0.5%.* The measuring accuracy of torque within ±0.5%.* TIMER control the testing frequency . DELPHI edited software under the Chinese Windows system. The test software features better compatibility, beautiful interface, simply operation, easily being* maintained, expanded and upgraded.The measuring system was applied in actual temperature test in JL465Q1 and JL475 engine for several times, its precision was proven to be satisfied with the engineering demand.The meaning of theoretical study analysis on the heat transfer process of engine lies in predicting the thermal load level of engine, providing the basis for the thermal design of engine, and shorting the development period of the product. In the paper, the finite element method of heat transfer was employed to investigate numerically the heat transfer or thermal load inside engine. Because of the complexity of the engine construction, it is almost impossible to analyze entirely the heat transfer of the whole engine's construction. Thereby, the numerical models of the engine's main parts including cylinder block, piston and cylinder head were established respectively, and were analyzed numerically. The boundary conditions for the numerical analysis were calculated from the half-empiristic correlations with conjugation of experiment test. The numerical computations for the heat transfer of JL465Q1 engine's parts (cylinder block, piston and cylinder head) under different operation cases were performed. The computed results were compared with experimental results, and the deviations between which are within 5%. The reasons resulting in deviations between computed results and experimental results maybe caused by the not very accurate boundary conditions and measuring errors of experimental system...