Abstract
The parameters of blade trailing edge have an important influence on the performance of centrifugal pump and internal unstable flow. In this study, the influences of cutting angles of blade trailing edge on unstable pressure pulsation and unstable flow structure are investigated using a centrifugal pump under off-design conditions through large eddy simulation. Three typical blade trailing edges, namely, original trailing edge (OTE), 15° cutting angle of blade trailing edge (OBS15) and 30° cutting angle of blade trailing edge (OBS30), are analysed. Results show that the cutting angle of blade trailing edge has a certain effect on the performance of the centrifugal pump. Under part-load conditions, the OBS30 impeller evidently contributes to the reduction in pressure pulsation intensity. By contrast, the OBS15 impeller has opposite effect because of the increase in wake vortex intensity. The OBS30 impeller can effectively improve the unstable vortex structure caused by backflow at the centrifugal pump tongue using a new Ω method. Consequently, reduction in the unstable flow structure mainly contributes to the reduction in pressure pulsation used by the proper cutting angle of blade trailing edge.
Highlights
Centrifugal pumps, as the core components of fluid transportation systems in industrial production, are widely used in aerospace, petrochemicals and military ships [1]
Zhang et al [18] evaluated the influences of splitter blades on the flow characteristics of centrifugal pump impeller outlet, and the results show that the addition of splitter blades can optimise the structure of the impeller wake region and improve the velocity distribution of the impeller outlet
The influences of the cutting cone angle of blade trailing edge on unstable pressure pulsation and unstable flow structure were studied in the centrifugal pump under off-design conditions through large eddy simulation (LES)
Summary
Centrifugal pumps, as the core components of fluid transportation systems in industrial production, are widely used in aerospace, petrochemicals and military ships [1]. Unstable flow in centrifugal pumps has an important impact on their efficiency and stability. Centrifugal pumps frequently work under off-design conditions to meet the work requirements. Under part-load and overload conditions, the flow in centrifugal pumps is extremely unstable [2,3]. The rotor–stator interaction at the tongue and the shedding vortex at the blade trailing edge are the main causes of unstable pressure pulsation in centrifugal pumps [7,8]. The internal flow of centrifugal pumps is extremely complicated and is accompanied by a 3D transient unstable strong turbulent motion that is difficult to capture. With the rapid development of high-performance computing equipment and technology, numerical simulation methods based on computational fluid dynamics have been widely used to study the unstable flow characteristics in fluid machinery [9,10]
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