... head coefficient was essentially eliminated for relative flow rates above 50% relative flow. Below 47% relative flow, a rotating stall-phenomenon was identified. The stall cell propagated at a rate of 0.4 times the impeller angular frequency, and we identified a propagation mechanism related...

... and propagation mechanism of the rotating stall of the hump instability region. The frequency characteristics and spatial intensity distribution of the stall cells are studied by adopting the proper orthogonal decomposition (POD) method. The results indicate that the energy loss at 0.80Q DES and 0.75Q DES...

... was performed using the response surface method (RSM). In the case of an axial fan without the ASF, the backflow gradually increased in the spanwise direction toward the hub and the streamwise direction to the inlet passage (upstream), as the flowrate decreased, and the rotating stall was developed through...

... mode. Using the data of the unsteady pressure measurements and detailed investigation of unstable ranges on the pump turbine characteristics, flow instabilities in the low-specific speed model pump turbine are analyzed. Relevant frequencies such as rotating stall, steady and unsteady vortex formations...

... be used to estimate the rotordynamic forces of impellers with similar specific speed. Depending on specific speed and the relative flow coefficient, many of these impellers are found to be excited by forward or backward whirl. Strong interaction with rotating stall typically appears in the force data...

... problems in no load or turbine brake operation. Unstable characteristics can be responsible for hydraulic system oscillations in these operating points. The cause of the unstable characteristics can be found in the blocking effect of either stationary vortex formation or rotating stall. The so-called...

... distortion as compared with counter-rotating inflow distortion. aerodynamics blades compressors fans flow measurement rotational flow turbomachinery wavelet transforms flow instability rotating stall static inflow distortion dynamic inflow distortion stall inception Stable...