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Mechanics, United Kingdom

Wheeler A.P.S.,University of Southampton | Wheeler A.P.S.,Aerodynamics and Flight Mechanics Group | Saleh Z.,Queen Mary, University of London
Journal of Propulsion and Power | Year: 2013

In this paper, the effect of cooling injection on the aerodynamics of tip flows in transonic turbines is investigated. Experiments are performed using an idealized model of a transonic tip flow. Schlieren photography, probe, and surface pressure measurements are used to determine the transonic tip flow structure and to validate the computational method. Computational simulations are performed to investigate the effects of cooling injection in a transonic blade environment. The results show that cooling injection has the potential to reduce overtip leakage loss. Copyright © 2013 by the von Karman Institute for Fluid. Source

Karabasov S.A.,University of Cambridge | Karabasov S.A.,University Research Fellow | Sandberg R.D.,University of Southampton | Sandberg R.D.,Aerodynamics and Flight Mechanics Group
18th AIAA/CEAS Aeroacoustics Conference (33rd AIAA Aeroacoustics Conference) | Year: 2012

A modern acoustic analogy method based on the Goldstein formulation is used for modelling the acoustic properties of several low Reynolds number jets from a DNS database. The key feature of this work is accounting for the well-developed turbulent boundary layer effects and the influence of the coflow. Fourth-order correlation analysis is applied for 3 jet cases of different inflow velocities and coflow speeds. The results for different jet cases are compared and contrasted from the viewpoint of the effect of coflow on jet noise. For two of the jet cases that correspond to the most converged DNS near-field data, far-field acoustic predictions are obtained and compared with the reference far-field DNS spectra. © 2012 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved. Source

Bleischwitz R.,University of Southampton | De Kat R.,Aerodynamics and Flight Mechanics Group | Ganapathisubramani B.,Aerodynamics and Flight Mechanics Group
AIAA Journal | Year: 2015

The aspect ratio of a membrane wing at moderate Reynolds number Re=67;500 affects aerodynamic performance as well as membrane deformations. Wind-tunnel experiments are conducted using three different lowaspect-ratio wings (aspect ratios of 1, 1.5, and 2). Aerodynamic performance is determined from force and moment measurements, which are performed using a six-component force transducer. Membrane deformations are obtained using photogrammetry. Mean values and unsteady effects are examined for both aerodynamic performance and membrane deformations. Mean deflection results indicate that lower-aspect-ratio membrane wings show defined Ushape deflections along the span, whereas higher aspect ratios display a progressive rise in deformation to the wing tip.Dominant chordwise vibration modes of the membrane and their spectral content show that lower aspect ratios exhibit higher mode shapes and frequencies, likely caused by increased downwash, which delays the influence of vortex shedding into higher incidence.The frequencies of the dominant modes in membrane motions are found tocorrelate with the frequencies of lift and drag fluctuations. Copyright © 2014 by the American Institute of Aeronautics and Astronautics, Inc. Source

Koopmans R.-J.,University of Southampton | Koopmans R.-J.,Aerodynamics and Flight Mechanics Group | Shrimpton J.S.,University of Southampton | Shrimpton J.S.,Aerodynamics and Flight Mechanics Group | And 4 more authors.
Journal of Propulsion and Power | Year: 2014

The most important parameters influencing the pressure drop over a reacting catalyst bed are analyzed using a multiphase multicomponent flow model. The model, in which the gas and liquid phases are treated as separate fluids, simulates the flow of highly concentrated hydrogen peroxide from a tank, through the injector, into the catalyst bed to the nozzle. It contains submodels to describe the interphase mass, momentum, and energy transfer occurring in the catalyst bed, in which it is assumed there is a pellet-based catalyst structure. The main purpose is to investigate the influence of pellet shape and dimensions on the pressure drop over the bed and the required bed length. The model has been verified and validated against experimental data and shows improved predictions of the pressure drop compared with traditionally employed pressure drop models. It is shown that cylindrical pellets with a diameter to length ratio larger than two give a lower pressure drop for a given bed length than spherical pellets. It is furthermore shown that this result is independent of the inlet mass flux and liquid volume fraction distribution and is reliable for high bed to pellet diameter ratios. Copyright © 2013 by the American Institute of Aeronautics and Astronautics, Inc. Source

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