Feasibility of Aerodynamic-Tab Jet Noise Suppressors in a Hypersonic Nozzle at Takeoff

Experimental Investigation of Jet Noise Sources in a Hypersonic Nozzle at Takeoff

“…The origin of the coordinate system is set at the center of the cowl lip, and x, y, and z axes are set along the streamwise, transverse, and spanwise directions, respectively. Figure 1 also shows a time-averaged schlieren image of the internal nozzle [3,5]. This nozzle operates under off-design condition (overexpansion mode) at takeoff, and it is designed so that the flow separates from the cowl wall intentionally to compensate for the undesirably large area ratio of the internal nozzle [3,5].…”

“…Rectangular Hypersonic Nozzle Figure 1 shows a schematic of the rectangular hypersonic nozzle [3,5]. The test nozzle consists of a ramp, a cowl, and sidewalls.…”

“…In the Japan Aerospace Exploration Agency (JAXA), a precooled turbojet (PCTJ) engine, which is capable of accelerating the vehicle from takeoff to Mach 5 with a single engine cycle, is under development [1][2][3][4][5]. In the PCTJ engine, a variable hypersonic nozzle with an external ramp is employed to compensate for the drastic change in the nozzle pressure ratio (NPR).…”

“…2 Graduate School Student, Department of Mechanical Systems Engineering, 1-5-1, Tenjin-cho, Kiryu, Gunma 376-8515, Japan. 3 Graduate School Student, Department of Mechanical Systems Engineering, 1-5-1, Tenjin-cho, Kiryu, Gunma 376-8515, Japan. 4 Associate Senior Administrator, Institute of Aeronautical Technology, 7-44-1, Jindaiji-Higashi, Chofu, Tokyo 182-8522, Japan, AIAA Member.…”

“…From the viewpoint of the noise suppressor design [3][4] for such a realistic hypersonic nozzle having complicated geometry and operating under off-design conditions, understanding the complicated behavior of the noise sources is quite important.…”