Development of a Numerical Method for Fluid-Structure Interaction Analysis in Hydrogen Diaphragm Compressor

The diaphragm compressors used in hydrogen fuel cell vehicle charging stations undergo repetitive structural deformation of the metal diaphragm in both upward and downward directions. Due to this characteristic, the capacity and lifespan of the compressor must be designed considering the stress distribution acting on the metal diaphragm. In this study, a 2-way fluid-structure interaction analysis methodology was introduced to derive the stress distribution acting on the metal diaphragm. The analysis was conducted for a single cycle with the suction and exhaust valves. In the fluid analysis results, the pressure changes of oil and hydrogen due to the piston motion of the oil piston wall, as well as the deformation of the metallic diaphragm, were observed. Moreover, based on these findings, it was possible to calculate the mass flow rates at the intake and exhaust valves. In the structural analysis results, the maximum stress was observed at the edge of the diaphragm. When the oil piston was positioned at Top Dead Center (TDC), the diaphragm experienced its highest levels of deformation and stress. The stress at this maximum stress point was approximately three times the average stress. Therefore, when designing the diaphragm, it is imperative to consider the concentration of stress in this specific region.