In this talk we characterize the transonic stationary solutions of the hydrodynamic escape problem (HEP), which is significant on studying the evolution of atmospheres of planets. The characterization is established by the geometric singular perturbation method (GSP) on the wind solution of HEP. We will discuss the existence and non-existence of the adiabatic wind solution with or without heat ...

In this paper we present a unigrid multi–model formulation for transonic flow calculations based on solving, in sequence, the full potential equation and the the Euler equations. The goal is to minimize the overall computation time to simulate steady flows by using a more computational efficient physical model in the early iteration steps. The proposed method is based on two steps. In the first...

An experimental study executed in the NPU NF-6 transonic wind tunnel on shock oscillations over SC(2)-0714 airfoil is presented. Tests are conducted at freestream Mach number from 0.72 to 0.82, Reynolds number based on the airfoil chord change from approximating 3.0 million to 5.0 million with transition strip fixed at 28% chord length. Limited span wise pressure distributions are obtained to v...

The benchmark active controls technology and wind tunnel test program at NASA Langley Research Center was started with the objective to investigate the nonlinear, unsteady aerodynamics and active flutter suppression of wings in transonic flow. The paper will present the flutter suppression control law design process, numerical nonlinear simulation and wind tunnel test results for the NACA 0012 ...

A CFD solver is developed to solve a 3D, unsteady, compressible Navier-Stokes equations with the Baldwin-Lomax turbulence model to study the unsteady separation flow in a high incidence cascade. The second order accuracy is obtained with the dual time stepping technique. The code is first validated for its unsteady simulation capability by calculating a 2D transonic inlet diffuser flow. Then a ...

We report on recent progress towards the development of a 3D optimization capability for transonic ow at high Reynolds numbers. In this paper we demonstrate optimization based on the 3D laminar Navier-Stokes equation, and we present validation of the ow analysis scheme based on the 2D Navier-Stokes equations with turbulence modelling.

In this paper, a systematic method to suppress transonic buzz with feedback is presented. A trailing edge control surface in the form of part-span flap was used only modify and unsteady aerodynamic loading on wing. The rotation provide feedback, which consisted weighted linear combination amplitudes principal modes structure, referred as law. linear, optimal law, that synthesized systematically...

A significant challenge to the application of evolutionary multiobjective optimization (EMO) for transonic airfoil design is the often excessive number of computational fluid dynamic (CFD) simulations required to ensure convergence. In this study, a multiobjective particle swarm optimization (MOPSO) framework is introduced, which incorporates designer preferences to provide further guidance in ...