Abstract
The macro characteristics and configurations of induced shock waves of the supersonic sprays are investigated by experimental methods. Visualization study of spray shape is carried out with the high-speed camera. The macro characteristics including spray tip penetration, velocity of spray tip and spray angle are analyzed. The configurations of shock waves are investigated by Schlieren technique. For supersonic sprays, the concept of spray front angle is presented. Effects of Mach number of spray on the spray front angle are investigated. The results show that the shape of spray tip is similar to blunt body when fuel spray is at transonic region. If spray entered the supersonic region, the oblique shock waves are induced instead of normal shock wave. With the velocity of spray increasing, the spray front angle and shock wave angle are increased. The tip region of the supersonic fuel spray is commonly formed a cone. Mean droplet diameter of fuel spray is measured using Malvern’s Spraytec. Then the mean droplet diameter results are compared with three popular empirical models (Hiroyasu’s, Varde’s and Merrigton’s model). It is found that the Merrigton’s model shows a relative good correlation between models and experimental results. Finally, exponent of injection velocity in the Merrigton’s model is fitted with experimental results.
Highlights
The macro characteristics and configurations of induced shock waves of the supersonic sprays are investigated by experimental methods
It is well known that several techniques can be used to improve the fuel atomization and mixing performance, such as high fuel pressure injection[1], high pressure compressed intake[2], intake manifold design[3,4] et al High fuel pressure injection is one of the most effective methods to improve the fuel atomization[5,6]
While the active cases occur in the supersonic spray or droplets which generate the induced shock waves, which are induced by supersonic body[19,20]
Summary
The macro characteristics and configurations of induced shock waves of the supersonic sprays are investigated by experimental methods. New phenomena may occur during the fuel atomization process with increasing of injection pressure[7,8] Among these phenomena, the supersonic fuel spray which break the speed of sound is an attractive phenomenon. Based on the interaction between spray and shock waves, the supersonic fuel atomization can be divided into two types: the active and passive case. For the fuel spray atomization in vehicle engines, the effects of high/ultra-high injection pressure on the characteristics of fuel spray field are always the research hotspots[23]. High-speed photography and Schlieren techniques are applied on the research of supersonic fuel spray atomization process, to quantitatively analyze the macroscopic characteristics of fuel spray and configurations of www.nature.com/scientificreports/. Comparisons between the popular Sauter Mean Diameter (SMD) models and experimental results are performed
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