Study on the Flow Characteristics of the Slender Body at Static and Dynamic State

Abstract

This paper is aimed at the problem of the aircraft’s post stall maneuver, simulate aircraft precursor with tangent-ogive cylinder and utilize pitch oscillation mechanism to simulate the dynamic process of the pitching motion of aircraft. Static and dynamic experiments were investigated in a low speed wind tunnel in NUAA. Quantitative PIV test results, model’s surface pressure distribution and leeward flow field were obtained. Experimental study shows: both symmetric and asymmetric flow field exist behind the slender body in the range of high angle of attack. When the angle of attack is 30°, the initial position of the asymmetric flow field is at 3.5D section of the slender body along the axis. When the angle of attack increases to 35°, the initial position of the asymmetric flow field moves to the 2.5D section position. The changing of the structure, intensity and spatial position of the leeward vortex during the dynamic pitching motion leads to the lateral and normal force hysteresis. Relative to the static state, the asymmetrical flow field position changed in the axial direction of the slender body during the dynamic pitching motion. The initial angle of attack of generating lateral force at the 3.5D cross section changed. In the upward pitching motion, the asymmetric flow field moved to the downstream and the initial angle of attack delayed from 30° to 40°. In the downward pitching, the asymmetric flow field moved upstream and the initial angle of attack is advanced from 30° to 20°.