Prediction of leakage and rotordynamic coefficients for the circumferential-groove-pump seal using CFD analysis

Abstract

The circumferential-groove seal is commonly used in various turbopumps to reduce leakage. The main goal of this paper is to develop the method of three-dimensional CFD analysis for determining leakage and rotordynamic coefficients of the circumferential-groovepump seal. A relative coordinate system was defined for steady-state simulation to calculate the velocity and pressure distributions of the seal clearance at each rotor whirl speed. Instead of setting the inlet and outlet pressures as the boundary conditions in the threedimensional CFD analysis, as it is more commonly done, we used the inlet velocity and outlet pressure obtained from a preliminary twodimensional CFD analysis. For prediction leakage, the presented analysis shows improvement from the bulk-flow model analysis. For the prediction of rotordynamic coefficients of K, k and C, the presented analysis provides results in closer agreement with the experimental values than those of the bulk-flow model analysis at several rotor speeds.

Analysis of the Impact of Special Constructions of Gap Seals on the Dynamics of Centrifugal Machines

“…The works of the creators of centrifugal machines [1][2][3][4][5][6] was devoted to the study of the relationship between the vibration characteristics of the rotor and the designs of gap seals. These works, as well as the needs of thermal and nuclear energy in feed, main circulation and other pumps for ever higher parameters stimulated a detailed study of the problems of hydrodynamics of gap seals and their effect on the vibration state of rotors of centrifugal machines [1,2,5,6].…”

“…The peculiarity of the works of most researchers of the influence of seals on the dynamics of a centrifugal machine is that the rotor and seals are considered as a closed hydromechanical system, in which the role of a connecting link is played by the flow of the pumped medium in throttling channels, inertial and hydrodynamic characteristics of the flow [3][4][5][6].…”

“…Gap seals, in addition to the function of sealing, perform an equally important function -to improve the vibration state of the rotor. Unfortunately, these functions, as a rule, are in mutual contradiction: constructive measures aimed at increasing the hydraulic resistance, most often worsen the dynamic qualities of seals, their hydrostatic stiffness and damping [3]. The efforts of the designers are aimed at harmonizing these functions.…”

CFD-Predicted Rotordynamic Characteristics for High-Temperature Water Liquid Seal Considering Tooth Deformation

“…With the development of computers, many scholars use CFD software to analyze the dynamics coefficients, Fengqin Li [18] used a single-frequency rotor whirling model to study the rotordynamic characteristics of a liquid annular seal. Generally speaking, the quasi-steady CFD-based method [19][20][21] and the transient CFD-based method based on the multiple-frequency rotor whirling models [22,23] are now the two advanced CFD methods in studying the circumferentially grooved liquid annular seals. The multiple-frequency rotor whirling model uses CFD dynamic mesh method, which requires a lot of computing resources and is prone to errors during the operation, the post-processing such as FFT transform is also required.…”

“…Not only that, the temperature of the fluid medium of some special pumps, such as plateau heat pumps, is also relatively high. However, most of the experiments and calculations of the liquid seal in the literature are based on the normal temperature [21,[24][25][26], ignoring the influence of the liquid pressure, temperature, and rotor centrifugal force, for example, Li et al [27] compared the rotordynamic characteristics of two types of liquid annular seals with parallelly grooved stator/rotor without considering the effects of the above three loads. Farzam [20] just gives the value of seal clearance under the thermal load, but detailed information is not given.…”