Project Details
Projekt
High-resolution simulation method for multiphase flow in rotating gaps
Applicant
Professor Dr.-Ing. Wolfgang Schröder
Subject Area
Technical Thermodynamics
Hydraulic and Turbo Engines and Piston Engines
Fluid Mechanics
Hydraulic and Turbo Engines and Piston Engines
Fluid Mechanics
Term
since 2023
Project identifier
Deutsche Forschungsgemeinschaft (DFG) - Project number 510921053
The flow field of screw compressors is characterized by a large range of fluid dynamic scales. Therefore, the numerical analyses are based on simplifications such as Reynolds-averaged Navier-Stokes formulations, one fluid approaches etc. which decrease the accuracy of the numerical data. This accuracy, however, is required to improve modeling formulations for flow fields of screw compressors. For this reason, a highly efficient high-resolution simulation method for the gas-liquid multiphase flow in the screw compressor gap is developed without exploiting the aforementioned simplifications. Since the physical properties of the two phases vary widely, two different numerical solvers for the two phases and a level-set solver to track the liquid-gas interface are used. The pressure gradient in the gap flow of screw compressors yields density changes in the gas phase. These variations in density are modeled by a finite- volume formulation. The liquid phase, however, is primarily incompressible. Therefore, the incompressible, thermal lattice-Boltzmann method is used to solve the conservation equations. A conservative level-set method is applied to accurately capture the topology of the deformable gas-liquid interface. A multiple marker method will be used to ensure strict conservation of individual bubbles. The turbulent flow of a large number of bubbles will be modeled by a large-eddy simulation. To improve the accuracy and efficiency of the multiphase model adaptive mesh refinement (AMR) will be exploited. This allows for a locally refined grid in regions at the gas-liquid interface and other regions of the flow with increased complexity. Furthermore, the solver will be efficiently parallelized. For the simulation of thousands of deformable bubbles, the resolution requirements of the gas-liquid interface lead to an AMR grid with on the order of billions of cells. Therefore, the coupled multiphase method is designed to take advantage of modern high-performance computing platforms. This will be achieved through a hybrid parallelization approach using the message passing interface for domain decomposition and the OpenMP interface to distribute the computational workload across many processors. The domain decomposition is continuously optimized during the simulation through the use of a dynamic load balancing algorithm. The data of the numerical analyses of Couette and Couette-Poiseuille flow with bubble-wall, and bubble-bubble interactions, as well as the bubble growth due to pressure gradients will be the essential basis for the model development in subproject A1.
DFG Programme
Research Units
