surge and rotating stall phenomena are two dynamic instabilities that occur in both axial and centrifugal compressors. surge is the stream instability phenomenon in compressor that imposes severe damages to the compressors. nowadays, suppressing surge phenomenon is one of the most important issues in oil and gas industries, especially when flow reduction or gas reflux is considered. this resear...

Ever increasing demand of higher pressure ratio of aero-engine compressors has always been hindered by two distinct aerodynamic instabilities. The first known as surge is; large one dimensional periodic mass flow fluctuation through the compressor, which involves the entire pumping system including compressor, ducting, plenum and throttle. The second is the rotating stall which can be character...

Force and supporting particle image velocimetry measurements were performed on a plunging NACA 0012 airfoil at a Reynolds number of 10,000, at pre-stall, stall, and post-stall angles of attack. The lift coefficient for pre-stall and stall angles of attack at larger amplitudes showed abrupt bifurcations with the branch determined by initial conditions. With the frequency gradually increasing, ve...

The ability to control the flow of water around the body dictates the performance of marine mammals in the aquatic environment. Morphological specializations of marine mammals afford mechanisms for passive flow control. Aside from the design of the body, which minimizes drag, the morphology of the appendages provides hydrodynamic advantages with respect to drag, lift, thrust, and stall. The flu...

Filopodia are thin cell extensions sensing the environment. They play an essential role during cell migration, cell-cell or cell-matrix adhesion, by initiating contacts and conveying signals to the cell cortex. Pathogenic microorganisms can hijack filopodia to invade cells by inducing their retraction towards the cell body. Because their dynamics depend on a discrete number of actin filaments, ...

Transfer of cattle to an unknown barn may result in a reduction in its welfare. Housing and management practices can result in signs of stress that include a long-term suppression of milk efficiency. The purpose of this study was to evaluate the influence of moving cows from the stanchion-stall housing to free-stall housing on their behaviour and production. The Holstein cows were moved into th...

In this paper, a numerical investigation into spike-type rotating stall process is carried out considering transonic compressor rotor (the NASA Rotor 37). Through solution of the Unsteady Reynolds-Averaged Navier-Stokes (URANS) equations, evolution from an initially circumferentially-symmetric near-stall flow field to stable condition simulated without adding any artificial disturbance. At oper...

The present research investigates the torsional aeroelasticity of the blade of an H-type vertical axis wind turbine subject to stall and post-stall conditions in various Reynolds regimes, which is experienced by the blade in a full revolution. In order to simulate the aerodynamics, a new model based on a combination of the Double Multi Streamtubes (DMST) model and the nonlinear multi-criteria C...

Surface pressure data from the National Renewable Energy Laboratory’s “Unsteady Aerodynamics Experiment” were analyzed to characterize the impact of threedimensionality, unsteadiness, and flow separation effects observed to occur on downwind horizontal axis wind turbines (HAWT). Surface pressure and strain gage data were collected from two rectangular planform blades with S809 airfoil crosssect...