Analytical indicial aerodynamic functions are calculated for several trapezoidal wings in subsonic flow, with a Mach number 0.3 Ma 0.7. The formulation herein proposed extends wellknown aerodynamic theories, which are...Analytical indicial aerodynamic functions are calculated for several trapezoidal wings in subsonic flow, with a Mach number 0.3 Ma 0.7. The formulation herein proposed extends wellknown aerodynamic theories, which are limited to thin aerofoils in incompressible flow, to generic trapezoidal wing planforms. Firstly, a thorough study is executed to assess the accuracy and limitation of analytical predictions, using unsteady results from two state-of-the-art computational fluid dynamics solvers as cross-validated benchmarks. Indicial functions are calculated for a step change in the angle of attack and for a sharp-edge gust, each for four wing configurations and three Mach numbers. Then, analytical and computational indicial responses are used to predict dynamic derivatives and the maximum lift coefficient following an encounter with a one-minus-cosine gust. It is found that the analytical results are in excellent agreement with the computational results for all test cases. In particular, the deviation of the analytical results from the computational results is within the scatter or uncertainty in the data arising from using two computational fluid dynamics solvers. This indicates the usefulness of the developed analytical theories.展开更多
The implementation of a turbulent gas-kinetic scheme into a finite-volume RANS solver is put forward,with two turbulent quantities,kinetic energy and dissipation,supplied by an allied turbulence model.This paper shows...The implementation of a turbulent gas-kinetic scheme into a finite-volume RANS solver is put forward,with two turbulent quantities,kinetic energy and dissipation,supplied by an allied turbulence model.This paper shows a number of numerical simulations of flow cases including an interaction between a shock wave and a turbulent boundary layer,where the shock-turbulent boundary layer is captured in a much more convincing way than it normally is by conventional schemes based on the Navier-Stokes equations.In the gas-kinetic scheme,the modeling of turbulence is part of the numerical scheme,which adjusts as a function of the ratio of resolved to unresolved scales of motion.In so doing,the turbulent stress tensor is not constrained into a linear relation with the strain rate.Instead it is modeled on the basis of the analogy between particles and eddies,without any assumptions on the type of turbulence or flow class.Conventional schemes lack multiscale mechanisms:the ratio of unresolved to resolved scales–very much like a degree of rarefaction–is not taken into account even if it may grow to non-negligible values in flow regions such as shocklayers.It is precisely in these flow regions,that the turbulent gas-kinetic scheme seems to provide more accurate predictions than conventional schemes.展开更多
基金the Royal Academy of Engineering for funding this researchthe use of the IRIDIS High Performance Computing Facility, and associated support services at the University of Southampton, in the completion of this work
文摘Analytical indicial aerodynamic functions are calculated for several trapezoidal wings in subsonic flow, with a Mach number 0.3 Ma 0.7. The formulation herein proposed extends wellknown aerodynamic theories, which are limited to thin aerofoils in incompressible flow, to generic trapezoidal wing planforms. Firstly, a thorough study is executed to assess the accuracy and limitation of analytical predictions, using unsteady results from two state-of-the-art computational fluid dynamics solvers as cross-validated benchmarks. Indicial functions are calculated for a step change in the angle of attack and for a sharp-edge gust, each for four wing configurations and three Mach numbers. Then, analytical and computational indicial responses are used to predict dynamic derivatives and the maximum lift coefficient following an encounter with a one-minus-cosine gust. It is found that the analytical results are in excellent agreement with the computational results for all test cases. In particular, the deviation of the analytical results from the computational results is within the scatter or uncertainty in the data arising from using two computational fluid dynamics solvers. This indicates the usefulness of the developed analytical theories.
文摘The implementation of a turbulent gas-kinetic scheme into a finite-volume RANS solver is put forward,with two turbulent quantities,kinetic energy and dissipation,supplied by an allied turbulence model.This paper shows a number of numerical simulations of flow cases including an interaction between a shock wave and a turbulent boundary layer,where the shock-turbulent boundary layer is captured in a much more convincing way than it normally is by conventional schemes based on the Navier-Stokes equations.In the gas-kinetic scheme,the modeling of turbulence is part of the numerical scheme,which adjusts as a function of the ratio of resolved to unresolved scales of motion.In so doing,the turbulent stress tensor is not constrained into a linear relation with the strain rate.Instead it is modeled on the basis of the analogy between particles and eddies,without any assumptions on the type of turbulence or flow class.Conventional schemes lack multiscale mechanisms:the ratio of unresolved to resolved scales–very much like a degree of rarefaction–is not taken into account even if it may grow to non-negligible values in flow regions such as shocklayers.It is precisely in these flow regions,that the turbulent gas-kinetic scheme seems to provide more accurate predictions than conventional schemes.
