Development of a Laplacian-based mesh generator for ALE calculations in rotary volumetric pumps and compressors

摘要

This paper describes a grid manipulator, which is capable of setting up block-structured grids for Arbitrary Lagrangian-Eulerian (ALE) computations of the internal flow in rotary volumetric pumps and compressors. The flow computations are performed with the commercial CFD software package StarCD. With structured grids, very high quality meshing in the gaps between the rotors and the rotors and the stator is possible. High quality grids are necessary for a correct computation of the leakage flow, which determines the volumetric efficiency. A second, more practical, reason for the use of block-structured grids for the moving parts of the grid is the simple data structure that is used for the storage of these grids. This allows the transfer of the grid between the CFD package and the developed grid manipulator only through the position of the nodes and without the need of transferring the complex and specific data structure used in CFD packages. The block-structured grids are constructed from the solution of the Laplace equation ▽~2(Φ) = 0 obtained on an unstructured grid in the same geometry. Adequate boundary conditions for the potential function are defined itera-tively. High quality meshes are constructed from the gradient lines and the potential lines. With the constructed meshes, a calculation of compressible flow in a tooth compressor is set up, which shows the applicability of the developed grid manipulator for these kind of flow problems.