Preswirl control and rotordynamic stability improvement of turbomachine seal equipped with newly designed spiral steering blades

Abstract

In turbomachine seal, preswirl generates the tangential force that induces the rotor vibration. Effective preswirl control can improve the rotordynamic stability. For this purpose, this study designs the spiral steering blades in front of the first seal tooth. Adjacent spiral steering blades form one spiral channel. The fluid is constrained and guided to flow along the spiral channel. The CFD results show that the new design reduces the leakage due to the additional throttling. The new design reverses the preswirl direction, optimizes the circumferential pressure distribution, and generates the negative tangential force. More spiral steering blades are better to reduce the tangential force. The new design largely reduces the effect of preswirl, and performs well under high preswirl condition.