Development Process of Shock Waves by Supersonic Spray

A numerical simulation of shock wave generation by high-pressure and high-speed spray jet has been conducted to compare to the experimental results obtained by X-ray radiographic technique. Using the space-time conservation element solution element (CESE) method and the stochastic particle techniques to account for fuel injections and droplet collisions, supersonic-spray-induced shock waves are successfully simulated. Similar to the experimental condition, a non-evaporating diesel spray in a chamber filled with inert gas sulfur hexafluoride (SF₆) at 1 atm pressure under room temperature (30° C) is simulated. To simulate the needle lift effect in the single-hole diesel injector, various injection-rate profiles were employed. In addition, the effects of discharge coefficients, with C_d ranging from 0.8 to 1.0, were also considered to simulate the shock generation processes in the leading spray front. Excellent quantitative match agreement with the experimental results is demonstrated in terms of the leading shock wave parameters, such as the Mach cone speeds and angles and the absolute density distributions in excess ambient gas, SF₆.