车用喷油泵“供油量不均”的原因与控制

喷油泵是柴油发动机的“心脏”,对它的各项技术性能要求很高,所以喷油泵必须在专用的试验台上进行调试。通常在使用中也不得随意变动。但有时会有这样的情况发生:经过专用试验台调试合格的喷油泵,装车使用后还会出现发动机功率不足、排气管冒黑烟、运转不稳定、异响等故障。出现以上故障(先排除其它因素的影响),还是与喷油泵的技术性能同发动机工作要求不匹配有关。其中最主要的是喷油泵各缸供油量与发动机所需的供油量不相适应而引起的“供油量不均”

Aerodynamic performance of high-turning curved compressor cascade with boundary layer suction

The impact of boundary layer suction on the aerodynamic performance of a high-turning compressor cascade was numerically simulated and discussed.The aerodynamic performance of a curved and a straight cascade with and without boundary layer suction were comparatively studied at several suction flow rates.The results showed that boundary layer suction dramatically improved the flow behavior within the flow passage.Moreover,higher loading over the whole blade height,lower total pressure loss,and higher passage throughflow were achieved with a relatively small amount of boundary layer removal.The integration of curved blade and boundary layer suction contributed to better aerodynamic performance than the cascades with only curved blade or boundary layer suction used,and the more favorable effect resulted from the weakening of the three dimensional effects of the boundary layer close to the endwalls.