Accuracy analysis of narrow groove theory for spiral grooved gas seals: A comparative study with numerical solution of Reynolds equation

Abstract

This study examined the accuracy of narrow groove theory for spiral grooved gas seals. Designed for compressible fluids, a finite difference method was proposed to solve the two-dimensional compressible Reynolds equation. The predictions of narrow groove theory were compared with those of the Reynolds equation. The typical performance parameters including gas film force, leakage, gas film stiffness, and torque were analyzed. The results show that the predictions of narrow groove theory generally agree with those of finite difference method when the number of grooves is more than eight. The gas film force, leakage, and gas film stiffness were slightly overestimated by narrow groove theory, with better accuracy for gas film force, leakage, and torque than for gas film stiffness. Although some cases showed deviation for gas film stiffness of as much as 52%, most deviations can be effectively ignored. Therefore, it is feasible to use narrow groove theory for qualitative analysis such as groove shape optimization. The present analysis provides the optimum groove parameters for the investigated seal.