Performance Simulation And Test Of Dongan M13 Gasoline Engine

Performance Simulation and Test of DongAn M13 Gasoline EngineWith the development of the world economy and the more emphases peoples put on the environment protection, Low fuel consumption and emission has been the main target of the vehicle development. So, the engine has become the focus. Many companies and institutes put more energy into the engine development field, more and more new technology has been applied to the designs for an engine, the technology makes the engine put out more power but consume less fuel. These improvements should be partly attributed to the law for environment protection which were established and modified by governments. In the 1960's the first law about car emission was passed in California USA, then the similar law were established in Europe and Japan. So some new technology aimed at the control of car emissions developed and applied very soon, such as electronic control on fuel injection, turbo, EGR, three way catalyst, unleaded gasoline, DPF, SCR, etc.In china, the laws about environment protection were established in the 1990's. And now the limits in these laws are closer to those in European laws year by year. To meet the request in these laws, many technologies about reducing friction are used in the developing engine. The engine working efficiency is promoted by the lower friction directly, and the fuel economic is better. The use of VVT made it possible that higher volumetric efficiency could be obtained in wide speed range of engine. In the developing process, the author established the model by using numerical simulation technology, and computed the performance of the developed engine. Before the designing work, the author provided some main parameters of intake manifold, exhaust manifold, cam phase, cam profile, etc. by computation, thus speeding up the designing work.In concept design phase, by using AVL-BOOST, the author set up a numerical model which employs the similar technologies with the developing engine, and calibrate the model, to estimate the effects of those technologies. Then a numerical model of the developing engine was set up by modifying the calibrated model. The main work was as follows:1. Estimating the friction loss. By using Lotus Engine Simulation v5.05(free ware) the friction loss of the engine was calculated, the result is that FMEP is 0.9493bar at 1000r/min, while 2.015bar at 6000r/min;2. Confirming the size of intake manifold and exhaust manifold. Considering room of the engine compartment, the range of intake manifold length is from 300mm to 370mm, the range of inlet port diameter is from 30mm to 37mm, the range of outlet port diameter is from 30mm to 35mm. After calculating, the conclusion was that the intake manifold length is 370mm, the inlet port diameter is 37mm, the outlet port diameter is 35mm, and the exhaust manifold has little effect on engines, for exhaust manifold, the inlet port diameter is 29mm, and the outlet port diameter is 35mm;3. Confirming the diameter of throttle valve. By calculating the engine performance with different valve diameter from 40mm to 50mm, we drew the conclusion that a throttle valve diameter of 50mm was most suitable for a powerful engine;4. Determining the cam phase. By optimizing the performance of different speeds, the best exhaust valve closing time is limited to 5°CA, at different speed the intake valve opening time is from -33°CA to 7°CA;5. Predicting engine performance. With the optimized results, the rated power of the engine could be 65.76kW@6000r/min, the max torque could be118.94 N·m@4500r/min.After the concept design it comes to a detail design phase. In this phase, the engineers would set up 3D models of components, draw a technical draft, and confirm tolerance and technical specification. The entire work is based on the concept scheme, design rules and requests of clients. When the detail design comes to an end, the main components of the engine will have been finalized; the size could be modified compared to the concept design result. Then the model in BOOST should be modified correspondingly. In addition, a new cam profile was designed, and the 3D model of port in cylinder head was set up too. Work in this phase is as follows:1. To modify the model in BOOST and select a better cam profile. Using new parameters the author modified the model in BOOST, and selected new cam profile by the calculated result. The new cam profile has a higher lift, and it could promote the performance at the range from middle speed to high speed, but the performance decreased slightly in low speed. Generally speaking, the new cam profile with higher lift was better.2. Calculating the flow coefficient. The author introduced the theory about port flow coefficient in detail, and calculated the port flow coefficient using 3D CFD software AVL-FIRE. So the accurate data about port flow could be used to the engine performance calculation.3. Optimizing cam phase. Because some parameters of engine changed, the cam profile and port flow coefficient changed too, the cam phase should be optimized to obtain the best performance. After these works, results were that the exhaust valve closing time is 5°CA, and the intake valve opening time is from -30°CA to 5°CA.4. Predicting engine performance. According to the optimized results, the rated power of the engine could be 66.46kW@6000r/min, the max torque could be116.4N·m@4500r/min.When the prototype engine with handwork components was assembled, the author tested the engine for performance on test cell. The author tested the performances of different cam phase using the camshaft with the variable phase, and got the result that the exhaust valve closing time is 5°CA, and the intake valve opening time is from -32°CA to 0°CA. tested performance on test cell is that the rated power of the engine could be 68.54kW@6000r/min, the max torque could be 118.33N·m@4500r/min. The max difference between the result from calculation and that from test was 3.2%. It indicated that the boundary conditions in calculation were selected correctly, and the result of simulation was effective. The performance of the engine exceed 66.4kW in rated power and 117N·m in max torque, these all meet the developing target.