Application of spray impingement technique for characterisation of high pressure sprays from multi-hole diesel nozzles

An attempt has been made to study and characterise the performance of two multi-hole nozzles of different nozzle hole geometry using the impingement technique. The technique was able to characterise the nozzle geometry and the near nozzle spray characteristics. The transients of the needle motion, dynamics of the pressure fluctuations were all reflected in the momentum flux measurements. The impingement distance had no significant effect on the derived injected fuel mass and the nozzle discharge coefficient. The momentum of the spray was observed to be strongly dependant on the fluctuations of the injection pressure but the average nozzle discharge coefficient for an orifice was not significantly influenced by different injection pressures. Numerous transients were observed to occur in the spray parameters over a single injection cycle and the transients in the spray were unique for an orifice and varied from one orifice to another in the same nozzle. This technique proves to be a vital tool for predicting the transient performance of high pressure nozzle flows.