Analysis of Flow Instabilities on a Three-Bladed Axial Inducer in Fixed and Rotating Frames

Abstract

The paper describes the results of recent experiments carried out in the Cavitating Pump Rotordynamic Test Facility for the dynamic characterization of cavitation-induced flow instabilities as simultaneously observed in the stationary and rotating frames of a high-head, three-bladed axial inducer with tapered hub and variable pitch. The flow instabilities occurring in the eye and inside the blading of the inducer have been detected, identified, and monitored by means of the spectral analysis of the pressure measurements simultaneously performed in the stationary and rotating frames by multiple transducers mounted on the casing near the inducer eye and on the inducer hub along the blade channels. An interaction between the unstable flows in the pump inlet and in the blade channels during cavitating regime has been detected. The interaction is between a low frequency axial phenomenon, which cyclically fills and empties each blade channel with cavitation, and a rotating phenomenon detected in the inducer eye.

Experimental investigation of cavitation characteristics for a high-speed inducer with a great flow rate

“…Therefore, the GFQ200-500 inducer with three blades can work normally at the designed flow value when it is matched with the pump. A comprehensive literature study about the pressure sensor location and pressure measurement method had been conducted, The outlet pressure sensor located about 1.5 times diameter downstream of the blade trailing edges 25 , while it located about one diameter downstream of the blade trailing edges 26 . Although the right pressure sensor location and pressure measurement method had been selected, 33 the inducer outlet whirl disturbed the pressure distribution of outlet pipe and enlarged the uncertainly of measurements.…”

“…The inlet pressure sensor located in 4 D t (which D t is tip diameter of inducer) upstream of the inducer blade leading edge, the outlet pressure sensor located in 2 D t downstream of the inducer blade trailing edge. 25,26,33 The pressure measuring method utilizes measurement points located on the circumference of the experimental pipe to attain accurate data, and the error associated with the head is ±1.5%. A control system software is used to obtain data on the rotating speed, torque, flow rate, and pressure, which is followed by calculating and exporting the results of shaft power and head.…”

“…An experiment was conducted at the fluid machinery test platform in Jiangsu University, Zhenjiang, China. 31–33 Considering the validation costs (the size of designed pump is very bigger) and particularity of submersible pump, 24–26,30 an independent experimental system of a high-speed inducer with great flow rate was built, and the cavitation performance was analyzed using high-speed photography. Moreover, hydraulic and cavitation curves were obtained, different cavitation development stages were classified, and distribution of the cavitation bubbles was analyzed.…”

Dynamic Model-Based Identification of Cavitation Compliance and Mass Flow Gain Factor in Rocket Engine Turbopump Inducers

“…The behavior of the cavitating volume was characterized via cavitation compliance and mass flow gain factor defined with respect to the upstream local pressure and incidence. Three different types of one-lobed azimuthal modes were estimated by the model and also observed in experiments: a super-synchronous forward rotating cavity [18][19][20][21][22][23][24][25][26], a backward rotating cavity [20][21][22][23] and subsynchronous rotating stall.…”

Research on Visualization of Inducer Cavitation of High-Speed Centrifugal Pump in Low Flow Conditions

“…Inducer cavitation causes vibration and affects the operation stability of the pump unit. Researchers have used the combination of transient pressure signal measurements and visual experiments to study the cavitation instability of the inducer [11][12][13].…”