Supersonic Flutter Analysis Based on a Local Piston Theory

Abstract

DOI: 10.2514/1.37750 A highly efficient local-piston theory is presented for the prediction of inviscid unsteady pressure loads at supersonic and hypersonic speeds. A steady mean flow solution is first obtained by an Euler method. The classical pistontheoryismodifiedtoapplylocallyateachpointontheairfoilsurfaceontopofthelocalmean flowtoobtainthe unsteadypressureperturbationscausedbythedeviationoftheairfoilsurfacefromitsmeanlocationwithouttheneed of performing unsteady Euler computations. Results of two- and three-dimensional unsteady air loads and flutter predictions are compared with those obtained by the classical piston theory and an unsteady Euler method to assess theaccuracyandvalidityrangeinairfoilthickness, flightMachnumber,andangleofattackandwiththepresenceof blunt leading edges. The local-piston theory is found to offer superior accuracy and much wider validity range compared with the classical piston theory, with the cost of only a fraction of the computational time needed by an unsteady Euler method.