Hot-Gas Side Jet in a Supersonic Freestream

Abstract

The present paper reports on the interaction of a hot side jet in a supersonic freestream and compares the effects with results from cold-gas jet investigations. With high-speed schlieren videos, a significant enlargement of the separation area has been ascertained upstream from the hot-gas jet and quantitatively confirmed with wall pressure measurements. The schlieren videos also show a strong oscillation of the separation and bow shock. By using an algorithm that analyzes the similarity of neighboring images, the oscillation frequency of the separation and bow shock has been measured to be 11.3 kHz. As a consequence of the dominant shocks in the area in front of the jet, the hot jet plume is screened off strongly from the freestream, thus resulting in an upstream inclination. Finally, highspeed videos have revealed large-scale structures in the hot-gas jet and their convection velocities have been analyzed. According to the shocks, the large-scale structures oscillate at 11.3 kHz. Jet oscillation is thus excited by the interaction of the hot-gas jet with the freestream and not by resonances from the combustion chamber. Nomenclature A J = jet exit area, m 2 C pdif = differential pressure coefficient, measured with and without jet flow D = diameter of the cylindrical part of model, mm d J = diameter of jet nozzle, mm d W = diameter of wind-tunnel nozzle, mm F = jet exit thrust, N I = jet exit momentum flux, N M J = Mach number of the side jet M 1 = Mach number of the freestream n = number of frames p = local pressure, bar p t = total pressure of the freestream, bar p tC = total pressure of cold-gas jet in the chamber, bar p tH = total pressure of hot-gas jet in the combustion chamber, bar p 1 = static pressure of the freestream, bar Re D = Reynolds number based on the model diameter D T JC = temperature of cold jet, K T JH = temperature of hot jet, K T tC = total temperature of the freestream and cold jet flow, K T 1 = static temperature of the freestream, K U c = convection velocity of jet flow, m s 1 U J = velocity of jet flow, m s 1 U 1 = velocity of freestream, m s 1 x = distance downstream from the model tip, mm z = direction of jet flow, mm = angle of attack, deg t = time between frames, s = angle of separation shock, deg ' = circumferential angle, deg = convection angle, deg = isentropic exponent = density, kg m 3 Subscripts J = jet exit condition JC = cold jet JH = hot jet t = static condition 1 = freestream

Effects of Turbulence Model on Prediction of Hot-Gas Lateral Jet Interaction in a Supersonic Crossflow

“…The pressure and temperature conditions for the study were obtained from the experiments conducted by Stahl et al 11,12 and are summarized in Table 1. The turbulence values were those used in the previous study 15 : It = 0.5% and lt = 2 mm.…”

“…More recent results from these authors include additional results from wind tunnel investigations on hot-gas lateral jet ejection 11,12 and an experimental and computational study on the substitution of hot-gas lateral jets by cold-gas simulants in supersonic flow. 13 Hold et al 14 performed a computational investigation based on the experimental data of Stahl et al, 11 finding that it was necessary to use a realgas, nonreacting, multispecies-based solution to most accurately predict the missile surface pressures due to the JI.…”

“…The objective of the present study is to extend the cold-gas lateral jet injection turbulence model investigation 15 to include the effects of (nonreacting) multispecies hot-gas injection. The data of Stahl et al 11,12 is used to validate the numerical predictions of surface pressure profiles resulting from the interaction of the jet with the supersonic crossflow. The results are also compared with the computations of Hold et al 14…”

Analysis of the Interaction Between Side Jet and Supersonic Free Stream Using K-factor

“…1b에 [4] , 전산유체역학의 발전에 따라 실험적 결과에 해석적인 방법을 보완하 여 마하 수의 영향, 받음각 및 제트 압력의 영향 등에 대하여 활발히 수행되고 있다 [3～10] . 최근에는 동체 효 과와 조종 날개 효과를 구분하여 해석하기도 하고 [7] , 제트에 의한 후방 와류 흐름 영향 [8] , 제트와 외부 대 기의 화학적 반응에 의한 영향 [9] , 및 뜨거운 제트 흐 름에 따른 영향 [10] 까지도 고려하여 상호 작용 현상에 [11] . 상호작용 계수가 음수이면 측추력 방향과 반대방향의 추력발생을 의미한다.…”

Turbulence Model Effects on Cold-Gas Lateral Jet Interaction in a Supersonic Crossflow

“…Some data for the DLR model were obtained for a hot-gas jet [11], for which the model diameter was 70 mm but the jet nozzle diameter remained 4 mm. More recent results from some of the same authors included additional results from wind-tunnel investigations on hot-gas lateral jet ejection [14,15] and substitution of hot-gas lateral jets by cold-gas simulants in supersonic flow [16].…”