Application of recess vaned casing treatment to axial flow compressors

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Flow estimation for the Persian Gulf using a Kelvin wave expansion

Hydrodynamic simulations of tidal currents in the Persian Gulf are presented. Water surface level and velocity have been determined by a Kelvin wave expansion as a new hydrodynamic calibration tool for estimating the dynamical field and flow patterns. In the procedure, leading to the Kelvin wave expansion, data of tidal constituents from co-tidal charts play a role. Results of the simplified model have been compared with both measurements as well with the results of a full reference hydrodynamic model to reveal that this calibration approach is a promotion not only towards simplicity, but also towards a speed up of the computation. Also a short-term oil spill simulation was undertaken. Comparison of the actual and simulated oil spill drift was found acceptable, allowing for future application in risk assessment analysis in the northern part of the Iranian waters.Electrical Engineering, Mathematics and Computer Scienc

Computational stall prevention using electromagnetic fields

The dangers of exceeding stall margin for an aircraft wing or its engine are severe. Stall occurs at high angles of incidence where separation occurs over control surfaces. Separation may be controlled using magneto-hydrodynamics (MHD) techniques if the flow can be electrically charged. In this preliminary study, a flow solver was developed based on the governing Navier-Stokes equations for compressible flows. The flow solver uses an implicit, high resolution, and Total Variation Diminishing (TVD) scheme. The flow solver was modified to include the effects of the electromagnetic field prescribed by Lorentz force. Two problems were investigated here. First, the separated subsonic flows are considered over a flat plate at high angles of attack. Second, an oblique shock wave leading to boundary layer separation is investigated for the flat plate in supersonic flows. For the case of subsonic flow, flow separation has been completely prohibited applying the electromagnetic field over the entire plate. The lift coefficient has been increased considerably. However, the overall drag coefficient has not been reduced noticeably. For the case of supersonic flow, the electromagnetic field was only applied in the vicinity of separated region in which it has been completely removed. Adequate amounts of the Lorentz force can be determined to evaluate feasibility of this technique for practical applications