Engineers at Sigma Designs Co., Springfield, N.J., used CosmosFloWorks CFD and FEAprogram CosmosWorks, both from SolidWorks Corp., Concord, Mass., www.solidworks.com.
"We created a single model, added boundary conditions to determine hydrodynamic forces, and distributed them across the blades," says Gerald Lynch, Sigma Design president.
The CFD software duplicated results of earlier physical measurements and provided more information than was available through experiments, including contour charts that show flow velocity, direction, pressure, and temperatures. "The software made it possible to optimize the turbine at about half the cost required by traditional methods," adds Lynch.
Traditional approaches would analyze the turbine using high-end and high-cost CFD and FEA software. An alternative was to put strain gages and encoders on the turbine, a time-consuming operation that would only have determined stress at a few points.
FloWorks, on the other hand, let engineers simulate blades turning and specify angular velocities using an Inlet-Swirl option. The software calculated fluid velocity and pressure values throughout the solution domain.
Turbine engineers then used the solid modeler to calculate moments of inertia for the structure, determine inertial loads, and add those forces to the hydrodynamic loads calculated in CFD to determine a total-load package for the FEA program. FEA revealed high stresses in a few areas and low stresses in others, so material could be redistributed to where it is needed or eliminated. Load information also helped in specifying bearings.