Three-dimensional Transient Numerical Analysis Of Twin-screw Supercharger

Compared with conventional turbocharger, due to the advantages of excellent low speed torque characteristic and good transient response, twin-screw supercharger has more huge development space in matching with engine. However, exhaust pressure pulsation, gas leakage and other issues seriously affect the performance of twin-screw supercharger. According to the three-dimensional transient numerical simulation analysis by CFD, this paper obtains the flow characteristics of twin-screw supercharger which can provide reference for structure design, performance optimization and engine matching.This paper uses HyperMesh software to reasonably simplify the actual model of twin-screw supercharger and divide surface mesh for simplified model under the premise of high fidelity of geometric model. According to the three-dimensional transient numerical simulation analysis by CONVERGE, this paper presents the fluid flow of supercharger and analyzes the overall distribution of pressure field, temperature field, velocity field and turbulence intensity.According to the results of simulation calculation, this paper finds the point-in-time when exhaust pressure pulsation is stronger or weaker and the location where the gas leakage is maximum or minimum and analyzes the causes of these two problems and flow losses caused by these two problems. Exhaust pressure pulsation and gas leakage result from clearance between components of twin-screw supercharger, so these two problems are inevitable. But we can improve supercharger’s performance by optimizing its structure.According to simulation under different speed or different compression ratio, this paper obtains gas flow characteristic curve and exhaust pressure pulsation curve under different conditions of twin-screw supercharger. There are different degrees of exhaust pressure pulsation to affect the performance of supercharger when the supercharger’s work condition deviates from the design condition, this can provide the reference for speed and compression ratio of twin-screw supercharger when matches with engine.