Experimental Investigation of the Supersonic Flow over an Axisymmetric Ring Cavity

Abstract

533.6.011This paper presents the results of the experimental investigation of the supersonic fl ow over a ring cavity of rectangular cross-section on a cylindrical body with a conical tip. The evolution of the fl ow over a cavity with its continuously changing extent has been investigated. The transition zone boundaries within which both an open and a closed schemes of fl ow are possible have been determined by the parameter of the relative extent of the cavity. It has been shown that the fl ow conditions in the transition zone depend on the prehistory of the fl ow. The main stages of cavity fl ow restricuting at the transition zone boundaries have been described.Introduction. The supersonic fl ow over rectangular cavities was investigated experimentally and numerically in [1][2][3][4][5][6][7][8][9][10][11][12]. Depending on the ratio of the length of the cavity L to its depth h, two different fl ow schemes are possible [1,2], an open cavity is formed. In this case, throughout the region of the cavity a subsonic circulatory fl ow 1 separated from the external supersonic fl ow by a mixing layer 2 is initiated (Fig. 1a). If λ exceeds some critical value (λ > λ C ), then a closed cavity is realized (Fig. 1b). In this case, in the cavity two isolated separation regions are formed, one of which (region 3) is formed behind the front step and the other (region 4) is formed behind the rear step. In the external supersonic fl ow fi eld, shock waves arise thereby: a compensation shock 5 ahead of the front separation region and a shock 6 ahead of the rear separation region. The range λ O < λ < λ C corresponds to the so-called transition region for which there is an additional classifi cation of fl ow schemes [1][2][3][4].The character of the supersonic cavity fl ow depends also on the state of the boundary layer at the cavity inlet and the Mach M and Reynolds Re numbers. For plane cavities of rectangular cross-section in supersonic turbulent fl ow in the range of moderate Mach numbers M = 2-4, there are empirical estimates of the boundaries of regions in which a particular fl ow scheme is realized: λ O = 10, λ C = 13. The results of experimental and numerical studies of the supersonic fl ow over axisymmetric cavities of rectangular cross-section on cylindrical bodies [5][6][7][8][9][10][11] are in good agreement with the data for plane cavities. Similarity of results connected with the collapse of plane, axisymmetric, and even free cavities is observed [13].Assuming that with decreasing λ the closed cavity opens when the separation regions localized behind the front step and ahead of the rear step come in contact with each other, the cavity collapse criterion was formulated; according to this criterion, the critical length of the cavity is equal to the total length of the above separation regions [1]. However, this criterion gives underestimated values [3], and therefore it was suggested [4] to take into account the correction for the total length of compression regions near the front and rear separation regions in the cav...

Dual Numerical Solution for 3D Supersonic Laminar Flow Past a Blunt-Fin Junction: Change in Temperature Ratio as a Method of Flow Control

“…It should also be noted that the possibility of existence of a non-unique solution in supersonic flow past a body, system of bodies, or their separate parts is well-known fact; the physical aspect of this problem consists in the strong nonlinearity of gas-dynamic processes. One of the examples is the experimental and numerical confirmation of the duality of the pattern of the supersonic flow past the model of an axisymmetric body with the rectangular ring cavity [19,20].…”