Shut-Off Head Prediction in Single Stage Centrifugal Pumps

Abstract

The prediction of the performance characteristic in centrifugal pumps at flow rates other than the design flow is of high relevance but relatively uncertain. In the present study, an evaluation of the existing shut-off head prediction methods and an assessment of both, the empirical approach and the numerical simulation are performed. For this purpose, after a review of existing methodologies, the empirical predictions are compared against available statistical data for single stage volute pumps. The CFD study, performed for 3 different single stage volute pumps with specific speeds between nq = 12 and nq = 54 is quantitatively compared against available model test data, which were obtained using precision manufactured hydraulic components. Several empirical methods from open literature have been reviewed for the shut-off head prediction. An overview of different prediction methods has been presented by Dyson [1], these and an empirical correlation proposed by Guelich have been compared against available data. The numerical study at shut-off condition requires a full-pump geometry, which also includes long suction and pressure pipes. Unlike several analyses present in the literature (Dyson & Texeira [2], Benigni et al. [3], Liu et al. [4]), which consider the internal leakage flow in the outlet boundary, the shut-off condition is obtained by imposing walls at inlet and outlet boundaries, but leakage flow through the gap between casing and impeller which is essential for the recirculation of the flow is numerically modeled. Because of the unsteady nature of the pressure in the pump volute, a transient simulation is performed and the predicted shut-off head is the average of the whole range of results for a minimum of 10 impeller revolutions.

Effects of the number of blades on impeller-volute interaction and flow instability of a centrifugal pump

“…As well known in many works, 3,4,34 the BPF and harmonic frequencies are generally observed when the impeller blades interact with the volute tongue. Indeed, in Figures 5–7, it is confirmed that the BPF of each case ( f /Ω = 4, 6, and 8) and its harmonic frequencies are observed for all the performance parameters.…”

Cooling design of an aero-engine fuel centrifugal pump at shut-off

“…6 For the conventional fuel centrifugal pump, the operating time at shut-off is so short that the temperature rise in the pump is small and can be neglected, so the problem of the temperature rise in a conventional centrifugal pump at shut-off has rarely been studied. To date, studies on the shut-off condition for a centrifugal pump have mainly focused on the shut-off head [7][8][9][10] and the shut-off power. 11 However, in the case of the afterburner fuel centrifugal pump, the problem of the high fuel temperature rise at shut-off cannot be ignored.…”