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...

Data prefetching is an effective way to hide memory latency. Current microprocessors allow multiple prefetch requests to overlap and provide a queue structure to track the outstanding requests. A prefetch request can either wait or be dropped when there is no available room in the queue. Recognizing the effectiveness and accuracy of the prefetches generated by the compiler, recent architectures...

A plain journal bearing is spontaneously unstable above a critical speed and loses much of its load carrying capacity when subjected to a load rotating at about half the speed of the shaft. The almost axially symmetric flow in a compressor can break down at low flow into a rotating pattern of stall cells but only the special case of a single propagating stall cell gives rise to a mechanical cou...

Vertical-axis wind turbines (VAWT) are excellent candidates to complement traditional and increase the total energy capacity. Development of VAWT has been hampered by their low efficiency structural unreliability, which related occurrence dynamic stall. Dynamic stall consists formation, growth, shedding large-scale vortices, followed massive flow separation. The vortex is detrimental turbine's ...

This paper presents the development and application of an adjoint-based optimization method to designing airfoils with the objective of alleviating dynamic stall effects in helicopter rotor blades. The unsteady flow problem is simulated using the NSU2D code, which is a two-dimensional unsteady, viscous, turbulent Reynolds averaged Navier-Stokes (RANS) finite-volume solver. The corresponding adj...