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| Simulation Analysis of the Effects of Inlet Water Injection on Knock and Combustion Process of A Gasoline Engine |
| DOI：10.13949/j.cnki.nrjgc.2022.05.010 |
| Key Words:gasoline engine inlet water injection knock combustion process spray characteristic |
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| Abstract:Taking a 1.5 L port fuel injection system gasoline engine as the research object， based on the test results of gasoline engine and the spray characteristics of the water injector， a three-dimensional model of the inlet port water injection gasoline engine was established by using AVL FIRE software. The development process and distribution state of the water spray were simulated and analyzed. The effects of 4 sets of water spray quality on the gasoline engine knock and combustion process were studied. The results show that the water mist is evaporated when it develops near the valve， and only a small amount of water mist enters the cylinder in liquid form. With the increase of water injection quality， the knock index（KI） decreases by 33.70% and the temperature and pressure curve in the cylinder gradually moves backward and downward. Compared with no water injection， when the water injection quality is 13.186 mg， the peak value of cylinder temperature decreases by 20.27 K and the peak value of cylinder pressure decreases by 0.48 MPa. When the water inflow in the cylinder is less than 5% of the fuel injection， the water mist has little effect on the knock and combustion process in the cylinder. The effect of water spray on the rapid combustion period is more significant. With the increase of water injection quality， the flame propagation speed decreases， the rapid combustion period is prolonged， the cumulative heat release rate curve moves backward， and the total combustion duration is prolonged by 2.5° crank angle. |
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