Effects of Unsteady Trailing-Edge Blowing on Delta Wing Aerodynamics

Abstract

The effects of unsteady trailing-edge blowing on delta wing aerodynamics were investigated experimentally to understand the aerodynamics-propulsion interaction for dynamic thrust vectoring. Two models with sweep angles of 50 and 65 deg, representing nonslender and slender delta wings, respectively, were tested in a water tunnel. Flow visualization and velocity and force measurements were conducted at stall and poststall incidences. For the periodic blowing, it was found that the dynamic response of leading-edge vortex breakdown and wing normal force coefficient exhibit phase lags for both nonslender and slender delta wings. The estimated time constants are larger than those reported in the literature for unsteady wings undergoing pitching or plunging. In the case of transient blowing, the time delay for the decelerating jet is significantly larger than that for the accelerating jet. The variation of the circulation and the reattachment process near the wing surface were studied by means of velocity measurements. The range of the estimated time constants is similar at the stall and poststall incidences for both the slender and nonslender wings.= dimensionless frequency, fc=U 1 q = freestream dynamic pressure Re = Reynolds number S w = wing surface area s = local semispan T = period t = wing thickness or time U jet = jet velocity U 1 = freestream velocity u = velocity X bd = distance from wing apex to leading-edge vortex breakdown location y jet = spanwise location of jet = wing incidence = jet pitch angle = circulation X bd = peak-to-peak amplitude of the variation of the vortex breakdown location = leading-edge sweep angle = fluid kinematic viscosity = air density = time constant = phase lag ! = angular frequency ! x = streamwise vorticity

Effect of thickness-to-chord ratio on aerodynamics of non-slender delta wing

“…Vortex breakdown types are categorized into seven different kinds [26], three of which are more common over delta wings, spiral, double helix, and bubble type. Sarpkaya [27], [28] [11], [35] and unsteady blowing [36].…”

Numerical Analysis of Various Types of Flows Over NACA 4415 Airfoil

“…Ahmad 8 and Bur et al 9 have evaluated the impact of spacing between each pair of VGs in the interim. Several additional studies have investigated sub-VG, micro-VG, and blowing VG to examine their impact on flow management [10][11][12][13] . The flow behaviour above the airfoil with and without VGs has been better understood using computational fluid dynamics (CFD).…”

Effect of Variation of Location of the Blowing on the Aerodynamic Characteristics over the Delta Wing

“…Cui et al [23] executed the forebody slot blowing over a delta wing with a 60-degree sweep angle. Jiang et al [24] carried out an experimental investigation on the effects of irregular blowing towards the trailing edge. over a delta wing with a sweep angle of 60 o .…”