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Parallelized Coupled Solver (PCS) Model Refinements & Extensions

Parallelized Coupled Solver (PCS) Model Refinements & Extensions. Sven Schmitz University of California, Davis. GE Wind November 29 th , 2007 Greenville, SC. Outline. 2007 Parallelized Coupled Navier-Stokes/Vortex-Panel Solver - PCS

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Parallelized Coupled Solver (PCS) Model Refinements & Extensions

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  1. Parallelized Coupled Solver (PCS)Model Refinements & Extensions Sven Schmitz University of California, Davis GE Wind November 29th, 2007 Greenville, SC GE Wind - PCS

  2. Outline 2007 Parallelized Coupled Navier-Stokes/Vortex-Panel Solver - PCS Nacelle Model, Latest version. 2008 Extension of Lifting-Line (LL) to Lifting-Surface (LS) - PCS Vortex-Lattice type method on the blade surface. ‘Quasi-Steady’ PCS - PCS-Q Quasi-Steady RANS/Vortex Model, Solution methodology for N blades. ‘Unsteady’ PCS - PCS-U Time-accurate RANS/Vortex Model, Solution methodology for N blades. GE Wind - PCS

  3. Navier-Stokes Biot-Savart Law (discrete) Boundary of Navier-Stokes Zone Vortex Method Bound Vortex Converged for … Vortex Filament Coupling of NS Solver with Vortex Method 2007 - PCS 2008 - PCS 2008 - PCS-Q 2008 - PCS-U GE Wind - PCS

  4. 2007 - PCS 2008 - PCS 2008 - PCS-Q 2008 - PCS-U • Nacelle Model : GEWIND-PCS_2_0.tar (avail. to GE) • Nacelle is approximated as a non-rotating ‘Rankine Body’. • User Input : Height, Width, Axial Location (dimens. by R) • Model finds position/strength of Source/Sink pair. • Influence coefficients are added to each point in RANS boundary. • => … acts as a perturbation to the incoming wind speed Uwind. • May reduce need for complex blade/nacelle grid topology. • No feedback from GE so far. • Latest Version : GEWIND-PCS_2_1.tar (avail. to GE) • New version of asymptotics for influence coefficients [Chattot, 2007]. GE Wind - PCS

  5. 2007 - PCS2008 - PCS 2008 - PCS-Q 2008 - PCS-U Extension of Lifting-Line (LL) to Lifting-Surface (LS) - PCS • Motivation : • Current PCS limited to LL at blade ¼ chord, vortex filaments emanating from trailing edge (TE). • Bound Vorticity GjB concentrated at LL. => Effect of LL position unclear. • Spread LL (respect. GjB ) along sectional chord to receive … • Gi,jB with GE Wind - PCS

  6. 2007 - PCS2008 - PCS 2008 - PCS-Q 2008 - PCS-U Extension of Lifting-Line (LL) to Lifting-Surface (LS) - PCS • Implementation : • Obtain Gi,jB from GjB using … • ‘Parabolic Plate’ vorticity distribution on RANS mesh. • Treat each blade surface element in RANS zone as an ‘Elemental Horseshoe Vortex’ located on the blade’s sectional camber line. • Determine influence coefficients for the Lifting-Surface (LS). • (… at small computational expense) • Satisfy the following conditions … Trailing Vortex Bound Vortex GE Wind - PCS

  7. 2007 - PCS 2008 - PCS 2008 - PCS-Q 2008 - PCS-U ‘Quasi-Steady’ PCS - PCS-Q • Motivation : • Current (steady) PCS limited to zero-yaw condition. • Extension of PCS as an efficient hybrid method for wind turbine blade analysis under yawed flow conditions. • Implementation : • Extend vortex model to account for yaw in vortex structure. Neglect ‘shed’ vorticity. • Solution methodology of a N-bladed wind turbine in yawed flow. • Converge to steady-state at each azimuth angle. PCS-Q is suitable for small yaw angles (<15deg), yet not capable of handling ‘dynamic stall’ and/or ‘blunt trailing edge airfoils’. GE Wind - PCS

  8. y=0deg CFX Solve N blades Vortex Model Converged to steady-state BC – u,v,w y=y+Dy 1/N Revolutions completed. 2007 - PCS 2008 - PCS 2008 - PCS-Q 2008 - PCS-U ‘Quasi-Steady’ PCS - PCS-Q GE Wind - PCS

  9. 2007 - PCS 2008 - PCS 2008 - PCS-Q 2008 - PCS-U ‘Unsteady’ PCS - PCS-U • Motivation : • PCS-Q limited to small yaw angles. • Extension of PCS-Q to a fully ‘unsteady’ hybrid method. • Implementation : • Extend vortex model of PCS-Q to account for ‘shed’ vorticity in vortex structure. (Perform subiterations on convection equation along helicoidal sheet) • Solution methodology of a N-bladed wind turbine in yawed flow. • Time-accurate solution of RANS/Vortex Model. PCS-U is capable of handling ‘dynamic stall’ and/or ‘blunt trailing edge airfoils’ through a fully unsteady solution methodology. GE Wind - PCS

  10. y=0deg CFX Solve N blades Vortex Model Converged or # subiterations Converged BC – u,v,w y=y+Dy # Revolutions until solution is periodic. 2007 - PCS 2008 - PCS 2008 - PCS-Q 2008 - PCS-U ‘Unsteady’ PCS - PCS-U GE Wind - PCS

  11. Research Proposal 2008 Extension of Lifting-Line (LL) to Lifting-Surface (LS) - PCS Useful extension of steady PCS. ‘Quasi-Steady’ PCS - PCS-Q 1st Step towards fully unsteady PCS, yet limited in capability. ‘Unsteady’ PCS - PCS-U Time-accurate extension of PCS-Q. PCS-Q/PCS-U require extended implementation/validation time. Detailed model specifications are to be discussed. GE Wind - PCS

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