The flow field characteristics about a fighter configuration at highangles of attack

Abstract

The flow patterns over a fighter configuration at high angles of attack are very complex. This paper will introduce the measured result of the flow field above a fighter configuration with a double delta wing. The measurement result of the flow field shows that the flow patlerns over the fighter configuration with double delta wing at medium to large angles of attack can be attributed to the following factors: the wing leading edge vortex and body vortex, the burst vortex flow and the full separation flow. When the burst point of the wing vortex approaches to the apex of exposed wing, the dimension of the flow with low energy is 5-8 times as large as the diameter of the body near the trailing edge of the wing. 2. Wind Tunnel and Test Condition The test was completed in the closed retern wind tunnel with an open test section at BUAA. The test wind speed was about 15m/ sec. Based on the mean aerodynamic chord of the wing, Reynolds number was about 320000. III EXPERIMENTAL METHOD During the course of the test, the measurement of the pressure and velocity distribution with the 7-holes probe was performed in the sections perpendicular to the axis of the wind tunnel. For each angle of attack tested, 2 to 5 stations along the axis were selected. The selected angles of attack and corresponding stations are shown in Table 1. Nomeclature C exposed root chord lengtn of ueing PO total pressure Coefficient u axis Velocity v30 free stream velocity a incidence