Recent Advances in Modelling Wind Parks in STAR CCM+ Steve Evans

Transcription

1 Recent Advances in Modelling Wind Parks in STAR CCM+ Steve Evans

2 Introduction Company STAR-CCM+ Agenda Wind engineering at CD-adapco STAR-CCM+ & EnviroWizard Developments for Offshore Simulation

3 CD-adapco: Engineering Success We are a growing and successful engineering simulation company 20%+ growth in FY2011 global software sales $130m End User Spend in FY2011 >560 employees in ~25 offices 40% of employees involved in Research and Development activities >9000 users worldwide Our purpose is to ensure the customer s success through the use of engineering simulation Enable & inspire innovation Reduce engineering time & costs We provide successful engineering simulation solutions Software products like STAR-CCM+ that are accurate, efficient, and easy to use Flow, Thermal and Stress simulation in a single tool. Local dedicated support Engineering services: technology transfer, burst engineering resources, custom software tools Our independence breeds engineering success Largest independent CAE/CFD provider Heavily invest in employees Continuously invest in development of new technology 3

4 Technical Value Why our software technology? From our customers perspective A single workflow environment Integrated Flow, Thermal, Stress Process One tool to learn with all the major physics Allows easy toggle from one task to another On the fly solver setting change Streamlined and effective modelling Rapid pre-processing & design change Reduced man-hours on model prep Streamlined meshing for highly complex models Rapid design change analysis: Stop, change, start from last Client-Server Efficiency of large models over multiple cores Eliminate lag-time in transferring models to/from clusters to workstation Custom automation Design of Experiment Deploy best-practices to new users quickly Ensure consistency

5 Wind Engineering with STAR-CCM+ We have been working with our customers in the Wind Energy Business for the past 5 years. Today we have customers working Automated wind and site Automated blade design Offshore and ship engineering Code coupling (CFD to FE) Acoustics

6 STAR-CCM+ EnviroWizard The EnviroWizard is a GUI driven work process allowing quick & efficient setup of investigations of Wind & Site problems using STAR-CCM+ Workflow process Terrain import Mesh Creation Boundary Conditions Polars (N directions) Post processing» Quantitative

7 Wake Interactions Modelling the turbine interaction problem can generally be split into two problems Near Wake Effects» 3D & tip effects, stall - High fidelity models BEM/CFD required Far wake (Wind Park Level) including» Wake interaction, turbulence & terrain - Lower fidelity model such as actuator discs can be used EnviroWizard allows the User to investigate wake interactions Automatic setup of mesh and actuator functions NASA AMES Wind Tunnel

8 Wake Interactions Each turbine is modelled individually as a momentum source. Torque Buffer Region 270 degrees, flow aligned grid Thrust» User can choose U in is area averaged velocity upstream of the disc Embedded meshing» Hexahedral dominant mesh in main region» Polyhedral disc & buffer region U in determined here Disc

9 EnviroWizard Developments While this automatic wake methodology works, the setup requires remeshing for each wind direction. In STAR-CCM (end Feb 2012), CD-adapco will release a version containing the Overset method, This has the possibility to simplify the array problem» No remesh.» Just change the wind direction and disc orientation. The EnviroWizard will be released at the same time incorporating this functionality.

10 Overset Methodology Cells are marked according to three types: active, inactive, and acceptor. Active cells» regular discretized equations are solved.» Donor for the interpolation. Inactive cells no equation is solved they are temporarily de-activated. Need to be surrounded by acceptor cells. Acceptor cells discretized equations are replaced by interpolation equations which express cell-centre value of a variable as a linear combination of values at another grid.

11 Overset Methodology

12 Overset Validation Steady State Re=50 cross flow cylinder, 24K elements Steady State Pressure Continuity Residuals Red overset Green no overset Steady State Velocity

13 Y Force Overset Validation Transient Re=200 cross flow cylinder, 24K elements Time 0 150s

14 Overset Features Release features for v702 (end Feb 2012) Any number of overlaps, restricted to:» Not overlapping each other» Not overlapping any solid body or exit background mesh Physics / Solver» Steady, moving, or sliding grid.» Parallel» VOF, cavitation etc.» Not particle tracking, liquid film

15 EnviroWizard with Overset New option in the Disc Models Setup of N turbines in array is performed with the Wizard. Test against a known case, Hornsref Overset disc The author wishes to acknowledge Elkraft who provided this production data and the owners of the array, Dong Energy and Vattenfall.

16 EnviroWizard with Overset Computational requirements Approximate timings for 5.9M cells» 1 background mesh with 80 overset regions Test machine 2*4 core Intel Xeon X GHz Setup & mesh» 15m Solver» elapsed time on 8 cpus = 38 s/iter Peak memory (coupled solver)» ~40 G Convergence

17 EnviroWizard with Overset 6 m/s case

18 Velocity EnviroWizard with Overset 6,5 6 5,5 5 Upwind Nearly Neutral STAR-CCM+ Overset 6 m/s case 4, Turbine number

19 Conclusions STAR-CCM+ is an open toolbox for simulating many aspects of wind engineering. Here we demonstrate a new feature of STAR-CCM+ v702 which has the possibility to greatly simplify the setup and calculation of offshore arrays using the overset method.