Compressor Surge: Simulation, Modeling and Analysis

Sammanfattning

The master thesis subject takes place in the automotive industry and specifically in the internal combustion engine area. The need of improving the efficiency of the engines leads to develop new technologies like turbo compressors. Some of the challenges to overcome are high rotational speed difficulties or extreme load and fatigue in the rotors. By design they are also prone to aerodynamic instabilities like compressor surge. These off design behaviors are not often studied by the manufacturers and therefore not so well known. The aims are to understand, analyze and possible ameliorate the sources of compressor surge; to identify surge causes; to create a way to reproduce the phenomena with robustness and precision; to be able to study potential solutions to eliminate surge noises. A literature review has been carried out. This would give good metrics to identify surge cycles. Based on the theory developed by Fink et al. (1992) a simulation model has been generated, followed by a process of calibration carried out using data acquired during field experiments. This method uses a fully modifiable simulation model in order to be able to be adapted to a wide range of turbo compressors. The predicted data by the model shows a reasonable agreement with the experimental data. This allows to test control laws with a surge valve or a high pressure gas recirculating valve. The knowledge alongside the simulation would help the team to better apprehend the problem on the future engine generations and have means to avoid the unwanted surge phenomena to occur.