Effect of thermal deformation on leakage clearance of claw hydrogen circulating pump for fuel cell system

The leakage clearance have a strong impact on the performance and reliability of hydrogen circulating pump in a fuel cell system, and the thermal deformantion is the most significant factor because of its high working temperature, small size. In this paper, the distribution of leakage clearance with different temperatures and rotors materials is obtained. The radial leakage clearance decreases with the increase of temperature in the working chamber. The axial clearance is increased by about 100  μm at rated working condition. When the material of rotors is aluminum alloy, the minimum radial clearance under rated working condition is about 8.5 μm, and the risk of interference is large. When the material of rotors is structural steel and titanium alloy, the radial clearance is maintained above 30 μm, and the risk of interference is small. The variation of leakage clearance leads to the variation of leakage area. The variation of total leakage clearance first increases and then decreases with the increase of angle. The minimum variation of total leakage area is 6.25  mm² at 0° and the maximum is 7.578  mm² at 84°. The total leakage area increased by 7.144 mm² on average. The results can be used as guidelines for the structural optimization of hydrogen circulating pump.