Hydraulic Axial Thrust in Multistage Pumps—Origins and Solutions

Abstract

In this paper, axial thrust problems of multistage pumps are presented. The entire investigation has been focused on the pump design concept having all impellers in series (facing in one direction) and is valid for barrel casing type as well as for segmental type. The major part of the investigation has been experimental on one stage testing arrangement, using also Laser Doppler Anemometry (LDA) for determination of fluid rotation in the impeller side chamber. Numerical flow analysis (NFA) has been applied for some flow variants in order to verify whether a numerical approach could simulate the test results. The phenomenon of fluid rotation in side chambers and its effect on impeller hydraulic axial thrust have been determined for different leakage flow regimes. The influence of increased wear ring radial clearance on axial thrust has been analyzed together with the solutions for pump hydraulic axial thrust reduction.

Methodology for the Residual Axial Thrust Evaluation in Multistage Centrifugal Pumps

“…The impeller shroud chambers have been analyzed with 2D axi-symmetric CFD simulations while a 3D model has been used for the central balancing drum. This choice is supported by the results shown by Gantar et al (2002) for geometries similar to the present one. Flow recirculation in the impeller exit area should not affect leakage flow rate in this case due to the small clearance that separates the main impeller passages from their own shroud chambers as reported by Gantar et al (2002).…”

“…This choice is supported by the results shown by Gantar et al (2002) for geometries similar to the present one. Flow recirculation in the impeller exit area should not affect leakage flow rate in this case due to the small clearance that separates the main impeller passages from their own shroud chambers as reported by Gantar et al (2002). As already reported, recently Thamsen and Bubelach (2011) denied this assumption in case of large gaps.…”

“…Over the pump operating range the main contribution to the axial thrust is due to the impellers flow fields, the leakage flows through wear rings and the pressure distribution that occurs inside the gaps between impeller shrouds and pump stationary walls. A detailed analysis of the origins of multistage pump unbalance has been proposed by Gantar et al (2002). They underlined the effect of cavity flows and off-design conditions but did not propose a procedure to couple the separated contributions coming from the pump components.…”

Laboratory Measurements the Rise in Power Consumption Resulting from the Use of a Finned Rotating Disc at a Centrifugal Water Flow

“…The issues related to the distribution of pressure in the turbomachinery near-impeller space are thoroughly discussed in reference literature. In the case of pumps, the problem involves analysing axial thrust characteristics (Bhatia 2014;Dong and Chu 2016a, b;Gantar et al 2002;Golovin et al 1989;Godbole et al 2012;Hong et al 2013;Iino et al 1980;Jedral 2001;Kalinichenko and Suprun 2012;Karaskiewicz 2013;Kim and Palazzolo 2016;Lefor et al 2015;Lugova et al 2014;Matsui and Mugiyama 2009;Piesche 1989;Rohatgi and Reshotko 1974;Shimura et al 2012;Wang et al 2013;Wilk 2003bWilk , 2009Zhou et al 2013) or volume losses resulting from untight sealing (Ayad et al 2016;Bhatia 2014;Cao et al 2015;Gantar et al 2002;Kim and Palazzolo 2016;Lefor et al 2015;Liu et al 2016;Shimura et al 2012;Torabi and Nourbakhsh 2016;Wang et al 2016;Wilk and Wilk 2001). So far, experimental (Ayad et al 2016;Dong and Chu 2016b;Gantar et al 2002;Godbole et al 2012;Hong et al 2013;Iino et al 1980;Lefor et al 2015;Nemd...…”

“…So far, experimental (Ayad et al 2016;Dong and Chu 2016b;Gantar et al 2002;Godbole et al 2012;Hong et al 2013;Iino et al 1980;Lefor et al 2015;Nemdili and Hellmann 2007;Owen and Pincombe 1980;Piesche 1989;Wilk and Wilk 1996b;Wilk 2008;Zhou et al 2013) and computational (Ayad et al 2016;Cao et al 2015Cao et al , 2016Dong and Chu 2016b;Dykas and Wilk 2008;Golovin et al 1989;Hong et al 2013;Karaskiewicz 2013;Kim and Palazzolo 2016;Lefor et al 2015;Liu et al 2016;Matsui and Mugiyama 2009;Piesche 1989;Rohatgi and Reshotko 1974;Shimura et al 2012;Torabi and Nourbakhsh 2016;Watanabe et al 2016;Zhou et al 2013) tests have been carried out. Selected works are devoted to cases of the centripetal or centrifugal flow (Ayad et al 2016;Bhatia 2014;Cao et al 2015;Dong and Chu 2016a;Gantar et al 2002;Golovin et al 1989;Iino et al 1980;Karaskiewicz 2013;Lefor et al 2015;Liu et al 2016;…”