Test results for leakage and rotordynamic coefficients of floating ring seals in a high-pressure, high-speed turbopump

Abstract

Test results are presented for short floating ring seals (D = 53.0 mm, L/D = 0.15) using a smooth surface and a round-hole pattern defined as a damper floating ring seal (h/C-r = 3, gamma = 0.34: the ratio of hole area to surface area) for supplied pressures of 3.0, 5.0, and 7.0 MPa, respectively, with the shaft operating speed up to 24,800 rpm. The measured data includes leakage, attitude angle, eccentricity ratio, and rotordynamic coefficients such as stiffness. damping, and inertia. When the floating ring seals are locked up, the eccentricity ratio of the smooth surface floating ring seal is lower than that of the damper floating ring seal. The attitude angle increases linearly with the operating speeds. The damping coefficients of the damper floating ring seal are higher than those of the floating ring seal. Whirl frequency ratios of the floating ring seal are lower than the damper floating ring seal with high eccentricity ratio at low operating speed range. The design parameters determined from these test results will be used for high-pressure and high-speed turbopump seals in a liquid rocket engine system.