Optimizing a Boundary-Layer-Ingestion Offset Inlet by Discrete Adjoint Approach

A large amount of low-momentum boundary-layer flow ingesting into a flush-mounted inlet can cause significant total pressure loss and distortion to the extent beyond operability of a fan/compressor. To improve the quality of incoming flow into the engine, shape optimization of the surface geometry at the inlet entrance has been carried out using the discrete adjoint method; the inlet-floor shape is parameterized by the use of control points on B-spline surface patches. To resolve the complicated geometry flexibly and wall-bounded turbulent flow accurately, an overset mesh system is well-suited for integrating the flow analysis code, sensitivity analysis code, and grid modification tools. To enhance the convergence characteristics of the sensitivity analysis code, additional numerical dissipation for the discrete adjoint formulation is introduced. After using this optimization procedure, the new inlet yields a significant improvement in performance: a more than 50% reduction in flow distortion and a 3% increase in total pressure recovery. High performance at off-design conditions is also realized with only slight degradation, confirming the capability of the adjoint method for a practical design problem. Finally, the physical meaning and implication of the performance improvement are elaborated upon in relation to the flow characteristics resulting from the new design.

[1]  Odis C. Pendergraft,et al.  Designing and Testing a Blended Wing Body with Boundary-Layer Ingestion Nacelles , 2006 .

[2]  Chongam Kim,et al.  Cures for the shock instability: development of a shock-stable Roe scheme , 2003 .

[3]  Doyle Knight,et al.  Automated Design of a Three-Dimensional Subsonic Diffuser , 2000 .

[4]  R. M. Hicks,et al.  Wing Design by Numerical Optimization , 1977 .

[5]  Luther N. Jenkins,et al.  Active Flow Control on a Boundary-Layer-Ingesting Inlet , 2004 .

[6]  B. Allan,et al.  Experimental and Computational Evaluation of Flush-Mounted, S-Duct Inlets , 2004 .

[7]  Brian G. Allan,et al.  Numerical Modeling of Active Flow Control in a Boundary Layer Ingesting Offset Inlet , 2004 .

[8]  B. H. Anderson,et al.  Vortex-generator installation studies on steady-state and dynamic distortion , 1996 .

[9]  Byung Joon Lee,et al.  Automated design methodology of turbulent internal flow using discrete adjoint formulation , 2007 .

[10]  C. T. Ting,et al.  A 727 airplane center duct inlet low speed performance confirmation model test for refanned JT8D engines, phase 2 , 1973 .

[11]  Haecheon Choi,et al.  Optimal Shape Design of a Two-Dimensional Asymmetric Diffuser in Turbulent Flow , 2004 .

[12]  K. Ikemura.  Development and application , 1971 .

[13]  A. Jirásek,et al.  Developement and application in design strategy for design of vortex generator flow control in inlets , 2006 .

[14]  Brian G. Allan,et al.  Optimal Design of Passive Flow Control for a Boundary-Layer-Ingesting Offset Inlet Using Design-of-Experiments , 2006 .

[15]  Kazuhiro Nakahashi,et al.  Aerodynamic Design of Complex Configurations with Junctions , 2006 .

[16]  F. Menter.  Two-equation eddy-viscosity turbulence models for engineering applications , 1994 .

[17]  Byung Joon Lee,et al.  Aerodynamic Redesign Using Discrete Adjoint Approach on Overset Mesh System , 2008 .

[18]  Bernhard H. Anderson,et al.  Optimal Micro-Scale Secondary Flow Control for the Management of High Cycle Fatigue and Distortion in Compact Inlet Diffusers , 2002 .

[19]  Meng-Sing Liou,et al.  Minimizing Inlet Distortion for Hybrid Wing Body Aircraft , 2012 .

[20]  Robert Liebeck,et al.  An experimental investigation of boundary layer ingestion in a diffusing S-duct with and without passive flow control , 1999 .

[21]  A. Jameson,et al.  Lower-upper Symmetric-Gauss-Seidel method for the Euler and Navier-Stokes equations , 1988 .

[22]  Joongkee Chung,et al.  Comparison of compressor face boundary conditions for unsteady CFD simulations of supersonic inlets , 1995 .