Large-eddy simulation of pulsed high-speed subsonic jets in a turbulent crossflow

Abstract

The jet in crossflow problem has been extensively studied, mainly because of its application to film cooling and injector design. It has been established that in low-speed flow, pulsing the jet significantly enhances mixing and jet penetration. This work investigates the effects of pulsing of high-speed subsonic jets (Ma∼0.47−0.77) on mixing and jet trajectory in turbulent subsonic crossflows by using large-eddy simulation. Jets with different density and momentum ratios are pulsed from an injector into a crossflow for a range of Strouhal numbers. Results are compared with the earlier low-speed cases to determine the sensitivity of jet penetration scaling on the relatively high Reynolds and Mach numbers of the current pulsed jets. It is shown that the classical momentum-ratio-based scaling (which reduces to the velocity ratio scaling in equal density low-speed case) can still be used for these high Reynolds and jet Mach number cases, although the scaling constant is slightly different. However, when the jet momentum ratio is different for the same Strouhal, Reynolds and Mach numbers, there is a significant change in the scaling constant, suggesting a sensitivity that could impact the original scaling relationship itself.

Keywords:

• pulsed jet
• jet in crossflow
• jet scaling
• compressible flow

Acknowledegments

This work is funded in part by Pratt & Whitney.