Theoretical and experimental analysis for leakage rate and dynamic characteristics of herringbone-grooved liquid seals

Abstract

In this paper, a theoretical analysis method for leakage rate and dynamic characteristics of herringbone-grooved liquid seals is proposed. Steady-state velocities and leakage rate are figured out first with the inertia term of the fluid combined with mass conservation within the seals. Subsequently, the rotordynamic coefficients are solved based on the investigation of Iwatsubo and Childs. Laboratory tests were performed on a specially designed test rig. Detailed comparisons between the experimental results and theoretical predictions show a good agreement on the leakage rate and hydraulic forces for five model seals, which provide an evidence of validation of the analysis method developed in this paper. Moreover, the influence of rotational speed and pressure difference on the leakage rate and rotordynamic coefficients of herringbone-grooved seals is discussed. The results show that the operating conditions and seal structures greatly influence the sealing and rotordynamic performances, which is helpful for designing herringbone-grooved seals.

Theoretical Solutions for Dynamic Characteristics of Liquid Annular Seals with Herringbone Grooves on the Stator Based on Bulk-Flow Theory

“…Experiments for three sets of model seals with herringbone grooves on the stator were conducted on a specially designed test rig shown in Figure 5 and the details of the test rig were described in [11].…”

“…Parts. Referring to the analysis method shown in [11], az-coordinate system is built to analyze the static characteristics of the spiral part. -Direction and -direction are, respectively, set parallel and perpendicular to the groove direction.…”

“…Arghir and Frene [10] proposed a bulk-flow analysis of static and dynamic characteristics of eccentric circumferentially-grooved liquid annular seals by using three types of control volumes and user-tuned constants. Zhai [11,12] developed two different theoretical analysis methods for leakage rate and dynamic characteristics of herringbonegrooved liquid seals and validated the method through comparing the predicted leakage rates and hydraulic forces with the experimental results. Ikemoto [13] derived a set of perturbation solutions for the bulk-flow governing equations of annular plain seals through third-order perturbations.…”

Dynamic analysis of liquid annular seals with herringbone grooves on the rotor based on the perturbation method

“…The vortex in the η -direction is supposed to diverge with angle γ and then go to the next land, as shown in figure 2 c . Referring to the method proposed by Zhai et al [ 25 ], a pressure equilibrium within the groove portion and the land portion in the η -direction and the ζ -direction between the effective pressure difference and pressure losses induced by wall friction and inlet and outlet pressure losses is applied to determine the leakage flow rates as well as the steady-flow velocities u ηl 0 , u ζl 0 , u θl 0 , u zl 0 , u ηg 0 , u ζg 0 , u θg 0 and u zg 0 .

Figure 2.

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“…Zhai et al . [ 25 ] developed a theoretical analysis method for the leakage rate and dynamic characteristics of herringbone-grooved liquid seals based on the method of Iwatsubo and Childs. The analysis method is validated through comparing the predicted leakage rates and hydraulic forces within five test seals with the experimental results.…”