Session: 05-03: Applied CFD

Paper Number: 130966

130966 - Fluid Flow Characteristics of Twin and Gerotor Screw Compressors 

The study examines the differences in fluid flow characteristics between two types of screw compressors called twin-screw compressor (TSC) and gerotor screw compressor (GSC). After rotors profiles are generated based on mathematical models of rotors, the 3D fluid analysis models of two types of screw compressors are constructed to investigate the fluid flow characteristics by using computational fluid dynamics (CFD). For a convenient comparison, the cross-sectional areas in the chamber of TSC and the outer rotor of GSC are designed as the same. The area efficiency and the helix angle of screw rotor is also the same. Under the same design conditions, three different GSC and TSC rotor lengths (120mm, 180mm, and 240mm) are examined to determine the influence of the design of screw compressors on output performance and compare their flow characteristics. The output mass flow rate, pressure, temperature, and their fluctuation properties are evaluated to distinguish the advantages and disadvantages of the two screw compressor designs. Simulation results have shown that increasing the length of the screw compressor can improve the mass flow rate, but that power losses and high leakage occur at higher lengths, which may have a negative impact on the efficiency of the compressor. The outlet average pressure of GSC is higher than TSC for the same length and the pressure fluctuation of GSC is relatively smaller than TSC in a suitable rotor length. In addition, the GSC design can achieve a relatively lower stable temperature through a smoother compression process. The smooth compression process leads to a smooth flow of fluid, resulting in low friction and stable temperature. Overall, the GSC has relatively more advantages such as higher flow rate, high operating stability, low leakage, less power loss, and greater efficiency than the TSC for all three lengths.

Presenting Author: Sheng-Yao Wang National Formosa University