Aerodynamic shape optimization of hovering rotor blades using a coupled free wake–CFD and adjoint method

Abstract This paper concerns a numerical optimization method for designing helicopter rotor blades in hover based on adjoint method and by using a coupled free wake–CFD approach for proper calculation of aerodynamic loads. The Euler flow solver and adjoint equations are formulated in a rotating coordinate system. The rotor wake effects are modeled by a free wake method and included into the CFD calculation. The approach is applied for the redesign of a transonic Caradonna–Tung two-bladed rotor through minor surface changes. The inviscid torque was reduced about 15% from that of original rotor due the reduction of wave drag. Results show that this technique is capable of converging to the optimum aerodynamic shape of rotor blades with minimum inviscid rotor torque coefficient under fixed thrust constraint. The advantage of this method is that satisfactory results can be achieved by minimum computational efforts, particularly for the grid generation problem and the required CPU time.

[1]  M. J. Rimlinger,et al.  Constrained Multipoint Aerodynamic Shape Optimization Using an Adjoint Formulation and Parallel Computers , 1997 .

[2]  Feng He,et al.  Aerodynamic airfoil design using the Euler equations based on the dynamic evolution method and the control theory , 2011 .

[3]  Ramesh K. Agarwal,et al.  Euler calculations for flowfield of a helicopter rotor in hover , 1986 .

[4]  Slawomir Koziel,et al.  Inverse Design of Transonic Airfoils Using Variable-Resolution Modeling and Pressure Distribution Alignment , 2011, ICCS.

[5]  Antony Jameson,et al.  Control theory based airfoil design using the Euler equations , 1994 .

[6]  Oh Joon Kwon,et al.  Aerodynamic Shape Optimization of Hovering Rotor Blades in Transonic Flow Using Unstructured Meshes , 2006 .

[7]  Antony Jameson,et al.  Case Studies in Aero-Structural Wing Planform and Section Optimization , 2004 .

[8]  Rainald Löhner,et al.  An adjoint‐based design methodology for CFD problems , 2004 .

[9]  Lee,et al.  Aerodynamic Shape Optimization of Rotor Blades in Hover Using Unstructured Meshes , 2004 .

[10]  David R. Clark,et al.  The Free Wake Analysis A Method For The Prediction Of Helicopter Rotor Hovering Performance. , 1969 .

[11]  Daniel A. Wachspress,et al.  A new approach to the free wake problem for hovering rotors , 1985 .

[12]  John Elwell,et al.  A Computer Model for the Evaluation of Helicopter Fire Control Systems , 1969 .

[13]  A. Jameson.  Optimum aerodynamic design using CFD and control theory , 1995 .

[14]  F. X. Caradonna,et al.  Experimental and Analytical Studies of a Model Helicopter Rotor in Hover , 1980 .

[15]  A. Jameson,et al.  Numerical solution of the Euler equations by finite volume methods using Runge Kutta time stepping schemes , 1981 .

[16]  K. Ramachandran,et al.  Rotor hover performance prediction using a free-wake, computational fluid dynamics method , 1989 .

[17]  C. Allen,et al.  CFD-based optimization of hovering rotors using radial basis functions for shape parameterization and mesh deformation , 2013 .

[18]  Christian B Allen,et al.  Aerodynamic shape optimisation of hovering rotors using compressible CFD , 2010, The Aeronautical Journal (1968).

[19]  Aviv Rosen,et al.  Free Wake Model of Hovering Rotors Having Straight or Curved Blades , 1988 .

[20]  Christian B Allen,et al.  Computational-Fluid-Dynamics-Based Twist Optimization of Hovering Rotors , 2010 .

[21]  R. M. Hicks,et al.  Practical design optimization of wing/body configurations using the Euler equations , 1992 .

[22]  Todd R. Quackenbush,et al.  Free wake analysis of hover performance using a new influence coefficient method , 1990 .

[23]  Patrice Castonguay,et al.  Aerodynamic shape optimization of hovering rotor blades using a Non-Linear Frequency Domain approach , 2011 .

[24]  Antony Jameson,et al.  Aerodynamic design via control theory , 1988, J. Sci. Comput..