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An experimental investigation of the effect of adverse pressure gradient on vortex breakdown by Gale Edward Treiber

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Published by Naval Postgraduate School in Monterey, California .
Written in English


  • Mechanical engineering

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ID Numbers
Open LibraryOL25336515M

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In fluid dynamics, an adverse pressure gradient occurs when the static pressure increases in the direction of the flow. Mathematically this is expressed as: / > for a flow in the positive is important for boundary layers, increasing the fluid pressure is akin to increasing the potential energy of the fluid, leading to a reduced kinetic energy and a deceleration of the . an experimental investigation of vortex generation in a turbulent boundary layer undergoing adverse pressure gradient new york university university heights, bronx, n.y. for langley research center national aeronautics and space administration washington, d. c. june i.~.   The spiral vortex breakdown, also named a vortex rope, may induce several low-frequency fluctuations leading to structural vibrations and a reduction in the overall efficiency of the turbine. In the present study, synchronized particle image velocimetry, pressure, and turbine flow parameter (Q, H, α, and T) measurements have been carried Cited by: Experimental investigations of laminar swirling jets had revealed a new form of vortex breakdown, named conical vortex breakdown, in addition to the commonly observed bubble form.

  A frequently employed method for aerodynamic flame stabilization in modern premixed low emission combustors is the breakdown of swirling flows; with carefully optimized tailoring of the swirler, a sudden transition in the flow field in the combustor can be by: vortex breakdown. Amongst them are the existence of an adverse pressure gradient and sud-den expansions in the flow. As most swirling flames may include these features, analogies were proposed between vortex breakdown in isothermal flows and enhanced flame propa-gationinvortextubes[36]. In these flows, a high pressure point along the axis of Cited by: 2.   We present an experimental investigation of a turbulent boundary layer flow at adverse pressure gradient of a joint PIV campaign of DLR and Universität der Bundeswehr (UniBw) München. The aim is to build up a data base to study existing and to develop improved proposals for the law-of-the-wall for adverse pressure : Tobias Knopp, Nicolas A. Buchmann, Daniel Schanz, Christian Cierpka, Rainer Hain, Andreas Schröder. The pressure variation in the Rankine vortex can be again computed by a balance between the pressure gradient and the centrifugal force. The total differential of pressure in the inner core is given by Eq. (), and by Eq. () in the outer region. Therefore, the rates of change of the piezometric head with radial distance for the core and.

An overall effect of adverse pressure gradients onto the wall pressure field statistics is an increase of the wall pressure fluctuations and a reduction of the convection velocity. This behavior was first observed by Schloemer () through an experimental study devoted to the investigation of the influence of a mild adverse pressure gradient. The adverse pressure gradient along the core constituted an internal (caused by swirl and stream tube divergence) and an external portion, which influenced the breakdown location. When the longitudinal momentum equaled the adverse pressure, the core flow stagnated, followed by a typical winding and dissipation to : Andrei Buzica, Christian Breitsamter. The effect of a moderate adverse pressure gradient on the interaction between a single streamwise vortex and a turbulent boundary layer is investigated experimentally. Quantitative characterization of vortex properties based on measurements of the mean cross-flow velocity components is by: This study is a detailed experimental investigation on aerodynamics of a NACA aerofoil by varying angle of attack from −12° to 20° at low Reynolds number flight regimes ( × 10 5 to 3 × 10 5).For this investigation, pressure distributions over the aerofoil were measured using a system including a pitot-static tube, a scanivalve unit and a pressure by: