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The spatial and temporal characteristics of transient diesel sprays impinging on unheated and heated walls were investigated by phase-Doppler anemometry (PDA) and the heat-transfer distribution in the vicinity of the impingement region was determined by fast response thermocouples. The results have provided quantitative evidence about the effect that the presence of the flat wall exerts on the spray characteristics. For example, independent of the thickness of the liquid film, the wall rearranges the droplet size distribution of the free spray with droplet collision and coalescence playing an important role in both the droplet redistribution and in the development of the wall-jet. Droplet sizes were reduced and mean tangential velocities increased with wall temperature at the upstream side and at the front of the wall-jet, respectively.

The spatial and temporal characteristics of the non-evaporating diesel sprays injected into the atmosphere through two pump-pipe-nozzle systems used in small DI diesel engines have been investigated by laser-single-beam deflection and phase-Doppler anemometry (PDA). The injectors used for these tests comprised a single-spring and a prototype two-spring multihole-type nozzle. The results provided quantitative information about the effect that the second spring exerts on injection duration and spray characteristics, i.e. it increases injection duration and, at the same time, improves fuel atomisation during the main injection period.