Experimental investigation of liquid jet injection into Mach 6 hypersonic crossflow

Abstract

The injection of a liquid jet into a crossing Mach 6 air flow is investigated. Experiments were conducted on a sharp leading edge flat plate with flush mounted injectors. Water jets were introduced through different nozzle shapes at relevant jet-to-air momentumflux ratios. Sufficient temporal resolution to capture small scale effects was obtained by high-speed recording, while directional illumination allowed variation in field of view. Shock pattern and flow topology were visualized by Schlieren-technique. Correlations are proposed on relating water jet penetration height and lateral extension with the injection ratio and orifice diameter for circular injector jets. Penetration height and lateral extension are compared for different injector shapes at relevant jet-to-air momentumflux ratios showing that penetration height and lateral extension decrease and increase, respectively, with injector's aspect ratio. Probability density function analysis has shown that the mixing of the jet with the crossflow is completed at a distance of x/d j * 40, independent of the momentum-flux ratio. Mean velocity profiles related with the liquid jet have been extracted by means of an ensemble correlation PIV algorithm. Finally, frequency analyses of the jet breakup and fluctuating shock pattern are performed using a Fast Fourier algorithm and characteristic Strouhal numbers of St = 0.18 for the liquid jet breakup and of St = 0.011 for the separation shock fluctuation are obtained.

Experimental Investigation of Liquid Fragmentation In Hypersonic Crossflow

“…The combustion efficiency of such engines depends strongly on the liquid jet penetration depth, atomization and the consequent mixing between the atomized fuel and the free stream air. Thrust vector controlling of missiles and transpiration cooling of the thermal protection system of space vehicles are other typical applications of liquid injection into hypersonic crossflow [91,16,30]. …”

“…One journal paper [16] and three AIAA 1 conference proceedings have been published [10,12,95]. The journal article [16] summarizes the work presented in Chapter 4; whereas the three conference articles summarize the works presented in Chapters 5 [12], 6 [95] and 7 [10] respectively. A comparison of the works presented in Chapters 4 and 7 is also published [9] as a contribution to a book, the Lecture Notes of the Lecture Series organized by the von Karman Institute 2 entitled "Liquid Fragmentation in High Speed Flows" [11].…”

“…All of the work presented in these internal publications have been supervised by the author of this thesis, and they all serve for the purposes mentioned in Section 1.1. Reference [89] focuses on the development of the post-processing tools, while references [15] and [94] are works on liquid injection and fragmentation. A literature survey is presented by [164].…”

“…This is necessary to avoid the possible blockage of the wind tunnel. A sketch of the flat plate model and a photograph showing the flat plate installed in the H-3 wind tunnel are shown in Figure 3.3 [15].…”

“…The range of jet Reynolds numbers based on the jet exit diameter d and the exit velocity, varied from Re = 11000 for low injection rates up to Re = 28000 for the highest injection rate. Figure 3.4 depicts a detailed view of the three injectors used during the investigation [16]. Throughout the experimental campaign, tap water at room temperature is used as liquid injectant.…”