Rotor wake and flow analysis using a coupled Eulerian–Lagrangian method

ABSTRACT A coupled Eulerian–Lagrangian methodology was developed in this paper in order to provide an efficient and accurate tool for rotor wake and flow prediction. A Eulerian-based Reynolds-averaged Navier–Stokes (RANS) solver was employed to simulate the grid-covered near-body zone, and a grid-free Lagrangian-based viscous wake method (VWM) was implemented to model the complicated rotor-wake dynamics in the off-body wake zone. A carefully designed coupling strategy was developed to pass the flow variables between two solvers. A sample case of a forward flying rotor was performed first in order to show the capabilities of the VWM for wake simulations. Next, the coupled method was applied to rotors in several representative flight conditions. Excellent agreement regarding wake geometry, chordwise pressure distribution and sectional normal force with available experimental data demonstrated the validity of the method. In addition, a comparison with the full computational fluid dynamics (CFD) method is presented to illustrate the efficiency and accuracy of the proposed coupled method.

[1]  Shi Yongjie,et al.  Numerical Method for Simulating Rotor Flow Field Based upon Viscous Vortex Model , 2012 .

[2]  Zhaohui Du,et al.  Investigation of Unsteady Flows and Noise in Rotor-Stator Interaction with Adjustable Lean Vane , 2014 .

[3]  Chengjian He,et al.  Modeling Rotor Wake Dynamics with Viscous Vortex Particle Method , 2009 .

[4]  James D. Baeder,et al.  High Resolution Wake Capturing Methodology for Hovering Rotors , 2007 .

[5]  Andrew M. Wissink,et al.  Application of Adaptive Mesh Refinement Technique in Helios to Blade-Vortex Interaction Loading and Rotor Wakes , 2011 .

[6]  Oh Joon Kwon,et al.  Unstructured Mesh Navier-Stokes Calculations of the Flow Field of a Helicopter Rotor in Hover , 2002 .

[7]  Massimo Biava,et al.  Single Blade Computations of Helicopter Rotors in Forward Flight , 2003 .

[8]  William G. Bousman,et al.  Technical Note: UH-60A Airloads Program Azimuth Reference Correction , 2005 .

[9]  Roger C. Strawn,et al.  30 Years of Rotorcraft Computational Fluid Dynamics Research and Development , 2006 .

[10]  Xu Guo-hua.  Numerical simulation of flowfield of helicopter rotor and fuselage in forward flight based on unstructured embedded grid technique , 2009 .

[11]  Hossein Saberi,et al.  Application of Computational Fluid Dynamics/Computational Structural Dynamics Coupling for Analysis of Rotorcraft Airloads and Blade Loads in Maneuvering Flight , 2012 .

[12]  Lakshmi N. Sankar,et al.  Recent improvements to a hybrid method for rotors in forward flight , 2000 .

[13]  HONG LUO,et al.  A Fast, Matrix-free Implicit Method for Computing Low Mach Number Flows on Unstructured Grids , 2000 .

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

[15]  L. Greengard,et al.  Regular Article: A Fast Adaptive Multipole Algorithm in Three Dimensions , 1999 .

[16]  Narayanan Komerath,et al.  A Review of Rotor Wake Physics and Modeling , 2011 .

[17]  P. Roe.  Approximate Riemann Solvers, Parameter Vectors, and Difference Schemes , 1997 .

[18]  Jasim Ahmad,et al.  Helicopter rotor blade computation in unsteady flows using moving overset grids , 1996 .

[19]  Tim Colonius,et al.  A general deterministic treatment of derivatives in particle methods , 2002 .

[20]  Robert E. Harris,et al.  Efficient Adaptive Cartesian Vorticity Transport Solver for Vortex-Dominated Flows , 2010 .

[21]  P. Spalart.  A One-Equation Turbulence Model for Aerodynamic Flows , 1992 .

[22]  J. Gordon Leishman,et al.  Rotor Free-Wake Modeling Using a Pseudo-Implicit Technique — Including Comparisons with Experimental Data , 1995 .

[23]  A. Chorin.  Numerical study of slightly viscous flow , 1973, Journal of Fluid Mechanics.

[24]  Wang Haowen,et al.  Simulating unsteady aerodynamics of helicopter rotor with panel/viscous vortex particle method , 2013 .

[25]  Mahendra J. Bhagwat,et al.  Development of a CFD-Based Hover Performance Prediction Tool for Engineering Analysis , 2005 .

[26]  Bo Wang,et al.  Numerical analysis on noise of rotor with unconventional blade tips based on CFD/Kirchhoff method , 2013 .

[27]  Lakshmi N. Sankar,et al.  Recent Improvements to a Hybrid Method for Rotors in Forward Flight , 2000 .

[28]  Qijun Zhao,et al.  Numerical simulations of the unsteady flowfield of helicopter rotors on moving embedded grids , 2005 .

[29]  Qijun Zhao,et al.  A New Single-blade Based Hybrid CFD Method for Hovering and Forward-flight Rotor Computation , 2011 .

[30]  Susan L. Althoff,et al.  Inflow measurements made with a laser velocimeter on a helicopter model in forward flight. Volume 4: Tapered planform blades at an advance ratio of 0.15 , 1988 .

[31]  Jayanrayanan Sitaraman,et al.  Evaluation of the Wake Prediction Methodologies Used in CFD Based Rotor Airload Computation , 2006 .

[32]  Richard E. Brown,et al.  Efficient High-Resolution Wake Modeling Using the Vorticity Transport Equation , 2004 .

[33]  Duck-Joo Lee,et al.  Numerical Simulation of Rotor Using Coupled Computational Fluid Dynamics and Free Wake , 2010 .