| XU Lei,ZHANG Yi,XU Chun-long,SONG Meng,PANG Hao-yu,ZHANG Yu,TANG Shi-zhe,LEI Li-jun.Prediction Model of New Erosion Life and Numerical Simulation of Transient Characteristics of a Diesel Fuel Injector[J],52(1):121-131, 177 |
| Prediction Model of New Erosion Life and Numerical Simulation of Transient Characteristics of a Diesel Fuel Injector |
| |
| View Full Text View/Add Comment Download reader |
| DOI：10.16490/j.cnki.issn.1001-3660.2023.01.013 |
| KeyWord:cavitation flow water hammer pressure nozzle orifice erosion life prediction |
| Author | Institution |
| XU Lei |
School of Energy and Power Engineering, North University of China, Taiyuan , China |
| ZHANG Yi |
School of Energy and Power Engineering, North University of China, Taiyuan , China |
| XU Chun-long |
China North Engine Research Institute, Tianjin , China |
| SONG Meng |
School of Energy and Power Engineering, North University of China, Taiyuan , China |
| PANG Hao-yu |
School of Energy and Power Engineering, North University of China, Taiyuan , China |
| ZHANG Yu |
School of Energy and Power Engineering, North University of China, Taiyuan , China |
| TANG Shi-zhe |
School of Energy and Power Engineering, North University of China, Taiyuan , China |
| LEI Li-jun |
School of Energy and Power Engineering, North University of China, Taiyuan , China |
|
| Hits: |
| Download times: |
| Abstract: |
| Aiming at the cavitation phenomenon and erosion wear problem in the nozzle hole of diesel fuel injector, by introducing the research theory of the pressure and jet velocity of cavitation bubbles with different distance near the wall, the traditional empirical formula is modified, and the transient characteristic simulation model of diesel fuel injector considering the erosion effect caused by the collapse of group bubbles in different boundary layers near the wall is established. Using the method of simulation, the influencing factors of the internal erosion wear degree of diesel fuel injection nozzle are explored, and the erosion wear life of the nozzle hole is predicted. Firstly, based on the research conclusions of the pressure and jet velocity of cavitation bubbles with different distance to the wall, the function fitting of the pressure and jet velocity of cavitation bubbles with different distance to the wall is carried out by using MATLAB software. Combined with the traditional empirical formula, the resistance correction empirical formula of group cavitation considering different distances from the wall surface is derived. Secondly, the finite element model based on resistance correction empirical formula and grid adaptive algorithm is established by using UDF in fluent. The Rrs cavitation risk prediction model is established by using the theory of representing erosion risk by steam mass condensation rate. The new model proposed in this paper is verified by Rrs cavitation risk prediction model and cavitation fatigue test results, It is proved that the new model proposed in this paper has good accuracy. Based on the calculation results of this model, the effects of nozzle orifice conicity Kfac and needle valve dynamic characteristics on orifice erosion wear are discussed. As the geometric size of the nozzle increases from Kfac0 to Kfac2 and Kfac4, the cross-sectional area of the orifice becomes smaller along the flow direction, the reflux near the wall and the separation of the boundary layer are restrained, the cavitation will be restrained, and the bubble interaction area near the wall will be reduced. At the same time, the fluid is more likely to generate eddy currents at the axis of the orifice, which will reduce the bubbles near the wall of the orifice, bubbles tend to be far away from the wall, so as to effectively inhibit the interaction between bubbles and the wall near the wall. The maximum jet velocity and water hammer pressure near the wall will be reduced, and the bubble collapse of the upper orifice will be reduced by 11.29% and 1.4% respectively; when the nozzle shape is the same, with the upward movement of the needle valve, the fluid area from the surface of the needle valve to the inner shell of the nozzle head increases, and the fluid has more space and time to adjust the flow path before flowing into the nozzle hole, which can flow into the nozzle hole at a smaller included angle with the axis of the nozzle hole, so that the backflow in the nearby area is weakened, the cavitation phenomenon is effectively restrained, and gradually shrinks towards the inlet of the nozzle hole. The effects of dimensionless distance on the transient maximum jet velocity and water hammer pressure at different distances from the wall are also studied. When the dimensionless distance δ=1.3, the maximum velocity and pressure are only 2.6% of that when the dimensionless distance δ=1.0. Therefore, the effect of bubble collapse at dimensionless distance δ>1.3 on erosion wear of wall surface can be ignored. Finally, the influence of nozzle hole conicity on nozzle hole life is explored. With the increase of nozzle geometric size from Kfac0 to Kfac2 and Kfac4, the minimum life of the inner wall surface of the upper nozzle hole is increased by 18.17% and 32.32% respectively. From the analysis results, it can be seen that the erosion wear area is mainly located at the upper wall near the inlet orifice. Therefore, it can be considered to do surface treatment on the wall near the inlet orifice to reduce the overall cavitation wear of the orifice, or appropriately increase the taper of the orifice during design and processing, so as to reduce the cavitation wear of the orifice and improve the service life of the orifice. |
| Close |
|
|
|