Spray Characteristics Of Spray Wall-impingement Under Common Rail System

As a inevitably occured phenomenon in the middle and small scale diesel engine,the spray wall-impingement often creates the fuel oil deposition wall surface,forms rich near wall mixture,causes high oil consumption and large CO and HC emissions. But if we use this phenomenon reasonably,could improve the fuel pulverization,promotion oil gas mix,finally,reduce the oil consumption and emissions. Therefore,to research the spray wall-impingement has the important meaning to the engine's optimization design and the sides of performance improvement.This article uses the high-pressured oil pump test platform,takes Freescale 16-bit microcontroller MC9S12DG128 as the control core,uses flashing light of ordinary digital camera as the synchronized signal,coordinates with the driving circuit of Injector and self-made atomization experiment box,established the test platform of spray wall-impingement. In this paper , the impact of the wall-impingement phenomenon was simultaneous recording,effects of injection pressure,impingement distance,impingement angle,the wall shape,the wall temperature of the fuel spray impingement was researched.The results show that with the improvement of injection pressure , fuel impingement after relatively increases,wall spray atomization effect further strengthen;Along with the increase of impingement distance,volume of after diffusion reduced;with impingement angle increases,the radius of upstream of impingement spray reduced,downstream of the spray radius is small changes,overall volume of spray increases slightly;the wall shape strong impact the shape and angle of the spray impingement the wall,the development of distance along the wall:arc raised < 90 degree raised < 135 degree raised,fuel bunch of rebound height: arc raised > 90 degree raised > 135 degree raised;surface temperature of the wall has a very important impact on the evaporation rate of the fuel impingement the wall , reducing the wall temperature,gas temperature above the wall becomes lower and the gas density near the wall becomes larger,droplet size increased significantly,and with the improvement of wall temperature,fuel evaporation rate is higher,spray atomization that hit the wall is improved,without affecting the spatial distribution of oil beam.