Performance prediction and flow analysis in the vaned distributor of a pump turbine under low flow rate in pump mode

Abstract

The main goal of this work is to investigate the possible different flow patterns existing in pump turbine under off-design conditions in pump mode. Numerical simulations by solving the Navier-Stokes equation, coupled with the "SST k-ω" turbulence model, were carried out. Flow characteristics were assumed to be stalled in the appropriate region of flow rate levels of Q/Q D =0.15-0.61. The simulation result was compared with experimental data and they showed good agreement. Consequently, velocity fields in three axial locations in stay vanes and guide vanes were analysed in details. It was shown that "jet-wake" flow pattern exists near the band, which changes little in the whole shape with flow rate increasing; to the middle location of vanes, reverse flow begins to appear on the interface between the runner and guide vanes, which will disappear gradually as the flow rate increases; massive reverse flow is captured near the crown, whose intensity will be weakened as the flow rate increases. Ultimately, it was found that the special head-flow profile can be ascribed to the special hydraulic loss characteristics of the stay vanes and guide vanes. pump turbine, flow simulation, stalled flow, guide vane Citation: Yin J L, Liu J T, Wang L Q, et al. Performance prediction and flow analysis in the vaned distributor of a pump turbine under low flow rate in pump mode.

Non‐linear modelling and stability analysis of the PTGS at pump mode

“…However, the study of the PTGS has received less attention compared with the hydro-TGS [17][18][19]. Most of existing literatures studied S-shaped regions at turbine mode and hump characteristics at pump mode using modern advanced approaches of computational fluid dynamics [20][21][22][23][24][25]. For example, Yin et al [23] investigated the possible different flow patterns existing in pump-turbines under off-design conditions of pump mode and found that the special head-flow profile is attributed to the special characteristics of hydraulic losses of the stay vanes and guide vanes.…”

“…Most of existing literatures studied S-shaped regions at turbine mode and hump characteristics at pump mode using modern advanced approaches of computational fluid dynamics [20][21][22][23][24][25]. For example, Yin et al [23] investigated the possible different flow patterns existing in pump-turbines under off-design conditions of pump mode and found that the special head-flow profile is attributed to the special characteristics of hydraulic losses of the stay vanes and guide vanes. Li et al [24] stated that the effect of vortex motion in the tandem cascade led to the small errors of hump characteristics between the results of simulations and physical experiments.…”

Analysis of Rotor-Stator Interaction in Turbine Mode of a Pump-Turbine Model

“…It leads to an obvious rise in the pressure and fluid velocities (Rodriguez 2007). A great number of studies were carried out on flow characteristics (Yin et al 2010(Yin et al , 2014, instabilities such as hump characteristics and S shaped characteristics (Wang et al 2011), and corresponding pressure fluctuations in pumpturbines. Pressure fluctuation is one of hot topics in pump-turbines.…”

Fluid flow analysis of drooping phenomena in pump mode for a given guide vane setting of a pump-turbine model

“…Furthermore, they only carried out the flow analysis in the partload region without addressing in detail the alteration of the characteristic curve in the part load regime, drooping zone load, best efficiency point (BEP) as well as overload regions and the associated flow patterns. Yin et al (2010) also carried out some similar work to predict the performance and flow pattern of a pump-turbine in pump mode, but this analysis was undertaken just in the vaned distributor at low flow rate. Other cavitation studies related to a pumpturbine in pump mode (Liu et al, 2013;Premkumar et al, 2014) investigated the relation between cavitation and pump mode.…”