Lei Qiao

Fully Local Formulation of a Transition Closure Model for Transitional Flow Simulations

A new computational fluid dynamics compatible transition model for the natural transition and laminar separation bubble induced transition is established using two transport equations with consideration of analysis results through linear stability theory linear stability theory. One transport equation is introduced to describe the growth of the laminar kinetic energy in the boundary layer. In addition, another transport equation of intermittency factor is built to trigger the transition by controlling the source term of turbulent kinetic energy equation. Finally, applying the two transport equations to a shear stress transport turbulence model completes a four-equation transition turbulence model. Comparisons of predictions using the new model with wind-tunnel experiments of the Schubauer and Klebanoff flat plate, S809 airfoil, Aerospatiale-A airfoil, and DLR-F5 wing validate the predictive qualities of the new transition turbulence model.

Combination of DES and DDES with a Correlation Based Transition Model

The present article describes the combination of the correlation based transition model of Menter et al. with the Detached Eddy Simulation (DES) and Delayed Detached Eddy Simulation (DDES) methodology. The interaction between transition model and DES or DDES method was investigated by T3A test case. The grid sensitivity of the combined methodology is discussed and the resolution is given. Then, the simulation of flow over foil of medium thick at stall angle was performed. The combined methodology produce results that have better agreement with experiment comparing to RANS transition model or fully turbulent DES/DDES alone. And the DDES based combined model shows a better agreement with experiment in the simulation of trailing edge separation comparing to DES based combined model.

Aerodynamic Shape Optimization Design of the Swept Wing Based on the Kriging Surrogate Model

The aerodynamic shape optimization design system was established in this paper. In the system, the RANS equation was used for solving the flowing; the free form deformation (FFD) method was used for the geometry parameterization, and the genetic algorithm was used for the optimization search. For the reducing of the time cost, the Kriging model was used for the surrogate model instead of the CFD simulation during the optimization design. The aerodynamic shape design of a swept wing was presented which used the system, and the result indicated that the 14% drag coefficient was reduced at the cruise conditions, which proved the validity of the system.

Modeling of Supersonic/Hypersonic Boundary Layer Transition Using a Single-Point Approach

Abstract During the process of aerodynamic shape design of supersonic and hypersonic space planes, laminar flow design and boundary layer transition prediction play important roles in aero-thermal numerical simulations and aero-thermal protection design. Therefore, in this study, a computational fluid dynamics compatible transition closure model for high speed laminar-to-turbulent transitional flows is formulated with consideration of the analysis results from stability theory. The proposed model contains two transport equations to describe the transition mechanism using local variables. Specifically, the eddy viscosity of laminar fluctuations and intermittency factor are chosen to be the characteristic parameters and modeled by transport equations. Accounting for the dominant instability modes at supersonic/hypersonic conditions, the first- and second- modes are modeled using local variables through the analysis of laminar self-similar boundary layers. Then, the present transition model is applied with compressibility corrected k

Parallel Compatible Transition Closure Model for High-Speed Transitional Flow

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POD-Kriging Reduced Method's Application in Tandem Cylinders' Flow

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A Study of Multi-Objective Aerodynamic Optimization Design for Variable Camber Airfoils and High Lift Devices

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A Blended Continuation Method for Solving Steady Inviscid Flow

shear stress transport turbulence model. Thus, as the main significance of the current work, the present model is enabled to capture the overshoot phenomena as well as predict the transition onset position. Finally, comparisons between the predictions using the present model and the wind tunnel experimental results of several well-documented flow cases are provided to validate the proposed transition turbulence model.

Aerodynamic Effects of Wing-Mounted Engine Nacelle on High-Lift Configuration of Turboprop Airliner

A single-point transition closure model that incorporates analytical results by stability theory in a reasonably wide range of Mach numbers has been formulated for supersonic/hypersonic boundary-la...