Experimental Study on Static and Dynamic Characteristics of Helically Grooved Seals

(Effect of Groove Dimensions)

Abstract

In the present study, the static characteristics (leakage flow rate) and dynamic characteristics (dynamic fluid film forces, dynamic coefficients, and whirl frequency ratio) of the helically grooved seals are experimentally investigated for various rotor spinning velocity, pressure difference, and groove dimensions. The results show that the leakage flow rate Q for the helically grooved seals decreases with helix angle γ and groove width g_w, and it becomes lower for small γ and g_w than that for the smooth seal. The cross-coupled stiffness coefficient K_c and whirl frequency ratio WFR of the helically grooved seals are smaller than those of the smooth seals and their values are always negative for any γ and g_w tested. The results obtained suggest that the helically grooved seals with small γ and g_w yield better performance characteristics from the viewpoint of reduction of leakage flow rate and suppressing the forward whirl motion of the rotor.