Study of Dynamic Tip Vortex Tracking in Rotorcraft CFD

This paper describes recent work on the application of vortex tracking grids (VTG) in a dynamic manner for a UH-60A rotor in hover to predict the blade airloads and wake. It was found that with appropriate time step size and limiters combined with an automated adaptation process using implicit hole-cutting that allows the nested vortex tracking grids to follow the tip vortices, reasonable computations of the blade section loading and wake geometry characteristics were obtained. While the results are currently inviscid, they indicate the potential of the VTG approach for wake capturing in an affordable manner, but more work is still needed to mature the approach for design application.

[1]  Peter F. Lorber,et al.  A Comprehensive Hover Test of the Airloads and Airflow of an Extensively Instrumented Model Helicopter Rotor , 1989 .

[2]  Mahendra J. Bhagwat,et al.  Development of a New Potential Flow Based Model for Hover Performance Prediction , 2005 .

[3]  Roger C. Strawn,et al.  Hovering Rotor and Wake Calculations with an Overset-Grid Navier-Stokes Solver , 1999 .

[4]  Brian E. Wake,et al.  Recent rotor wake simulation and modeling studies at United Technologies Corporation , 2000 .

[5]  Ewald Krämer,et al.  Tip Vortex Conservation on a Main Rotor in Slow Descent Flight Using Vortex-Adapted Chimera Grids , 2006 .

[6]  H. Huynh,et al.  Accurate Monotonicity-Preserving Schemes with Runge-Kutta Time Stepping , 1997 .

[7]  Nandita,et al.  Structured Adaptive Mesh Refinement (SAMR) Algorithms Applied to Rotor Wake Capturing , 2007 .

[8]  James D. Baeder,et al.  Implicit Hole Cutting - A New Approach to Overset Grid Connectivity , 2003 .

[9]  Jason Hill,et al.  A Priori Grid Adaptation for Helicopter Rotors Wakes Using Structured-Unstructured Hybrid Grids , 2005 .

[10]  Roger C. Strawn,et al.  Computational Modeling of Hovering Rotor and Wake Aerodynamics , 2001 .

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

[12]  Roger C. Strawn,et al.  CFD Simulations of Tiltrotor Configurations in Hover , 2005 .

[13]  James D. Baeder,et al.  Vortex Tracking Using Overset Grids for Quad Tilt Rotor in Forward Flight , 2004 .

[14]  James L. Tangler,et al.  A Prescribed Wake Lifting Surface Hover Performance Analysis , 1977 .

[15]  Brian E. Wake,et al.  Investigation of high-order upwinded differencing for vortex convection , 1995 .

[16]  Anton J. Landgrebe,et al.  An Analytical and Experimental Investigation of Helicopter Rotor Hover Performance and Wake Geometry Characteristics , 1971 .