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Book An Investigation of Cavities in Accelerating Supersonic Flow

Download or read book An Investigation of Cavities in Accelerating Supersonic Flow written by James Ronald Sachtschale and published by . This book was released on 1966 with total page 142 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Investigation of the Flow in a Rectangular Cavity in a Flat Plate at a Mach Number of 3 55

Download or read book Investigation of the Flow in a Rectangular Cavity in a Flat Plate at a Mach Number of 3 55 written by Russell W. McDearmon and published by . This book was released on 1960 with total page 46 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Experimental Investigation of Supersonic Cavity Flows and Their Control

Download or read book Experimental Investigation of Supersonic Cavity Flows and Their Control written by Ning Zhuang and published by . This book was released on 2007 with total page 176 pages. Available in PDF, EPUB and Kindle. Book excerpt: The study of supersonic cavity flows is of interest both from fundamental fluid dynamics and practical perspectives. The complex nature of this flowfield, consisting of compressible shear layers, compression/expansion waves, and fluid-acoustic interactions, makes it a rich problem to study. A detailed experimental study of supersonic flow (M=1.5 to 2) over a range of three-dimensional rectangular cavities (L/D=1 to 5.2) was conducted. The measurements included unsteady surface pressure measurements, particle image velocimetry, and flow visualization using shadowgraph and schlieren. Large-scale structures in the shear layer and a large recirculation zone in the cavity was observed. Spatial and temporal mode switching was also observed, the nature being different for short and long cavities. The shear layer characteristics of the two cavities are very different in term of curvature and growth. Supersonic microjets were used at the leading edge of the cavities to suppress the resonance in the flow. With a minimal mass flux (0.15%), the activation of microjets led to a large reduction in cavity tones (20 dB) and overall sound pressure levels (9dB). In addition, the microjet injection enhanced the shear layer mixing and reduced the velocity fluctuation in the cavities. The significant reductions together with the low mass flux requirements make this a potentially viable technique for full-scale, practical applications.

Book A Study on Axisymmetric Cavities in Supersonic Flow

Download or read book A Study on Axisymmetric Cavities in Supersonic Flow written by Brian Tyler Brooker and published by . This book was released on 2017 with total page 167 pages. Available in PDF, EPUB and Kindle. Book excerpt: The research presented in this dissertation focuses on understanding and passively controlling the unsteadiness of the flow that occurs in cavity flows. Flow passing over a cavity generates turbulent structures that result in pressure fluctuations in the cavity that exhibits itself as noise at selected tonal frequencies. The unsteadiness and the presence of the turbulent structures can be strong enough to damage the equipment that is stored in these cavities. Understanding the flow unsteadiness and determining the means to control it is an important research area that has been undertaken over the past several decades. High speed cavity flow presents several problems when used in practical applications. At lower speeds, vibrations can be controlled with ramps and/or flaps; however, there is a current need to provide a better understanding of supersonic flow around a cavity to allow future aircraft to release payload at high speed. Most of the previous research on cavity flows has been done on rectangular cavities and has provided guidelines for determining dominant frequencies and other flow properties over a cavity. This project focuses on understanding the flow unsteadiness in more of a basic configuration, namely over an axisymmetric cavity, to eliminate the effects of the side walls on the flow development. Such research is scarce in the literature, although it is a building block in understanding the nature of the cavity flows. The results of the current research agree well with the previous research conducted on rectangular cavities. The measured tonal frequencies match the predicted Rossiter modes that are well defined for rectangular cavities. The pressure data obtained at the cavity walls has shown a decrease in sound pressure levels at the various tonal frequencies when the cavity is lengthened. It is also shown that replacing the back wall of the cavity with a half-height wall results in both positive and negative effects to the tonal frequencies. At the front wall pressure fluctuations are reduced at all cavity lengths; however, the rear wall shows significant increase in pressure fluctuations for the medium and large cavity lengths.

Book An Experimental Investigation of Cavity Vortex Generators in Supersonic Flow

Download or read book An Experimental Investigation of Cavity Vortex Generators in Supersonic Flow written by Richard Hazlewood and published by . This book was released on 1995 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book A Study of the Flow Physics about 2 D Supersonic Open Cavities Using Numerical Simulations

Download or read book A Study of the Flow Physics about 2 D Supersonic Open Cavities Using Numerical Simulations written by Chung-Jen John Tam and published by . This book was released on 1997 with total page 242 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Flow Around an Object Projected from a Cavity Into a Supersonic Freestream

Download or read book Flow Around an Object Projected from a Cavity Into a Supersonic Freestream written by Scott T. Bjorge and published by . This book was released on 2004-03-01 with total page 90 pages. Available in PDF, EPUB and Kindle. Book excerpt: The pressure and flow field of a supersonic flow over a cavity, with and without a store, was the focus of this experiment. One cavity geometry (length to depth ratio 3.6) was studied; the freestream Mach number and the placement of the store relative to the cavity floor were varied. The pressure spectra on the cavity floor were markedly different between Mach numbers of 1.8 and 2.9. The Mach 1.8 case exhibited clear spectral peaks consistent with predictions by Rossiter, whereas the Mach 2.9 flow did not. With the store placed within the free shear layer, the pressure fluctuations on the cavity floor decreased for Mach 1.8 and increased for Mach 2.9. High-speed Schlieren photography was used to visualize the interaction of the free shear layer and the modeled store. Images revealed that flow structures in the free shear layer of the Mach 2.9 flow exhibited less spanwise coherence then their Mach 1.8 flow counterparts. Images also revealed vertical displacement of the free shear layer as the store traversed through it. Pressure-sensitive paint (PSP) was utilized to quantify the full-field mean pressure on the cavity floor and store. A pressure rise near the trailing edge was noted for both freestream Mach numbers. The mean pressure contour of the floor for the Mach 1.8 exhibited considerable three-dimensionality, despite the generally spanwise coherent structures in the free shear layer. (4 tables, 33 figures, 37 refs.)

Book Experimental investigation of upstream mass injection on a supersonic cavity flow

Download or read book Experimental investigation of upstream mass injection on a supersonic cavity flow written by Pablo Cesar Bueno and published by . This book was released on 2002 with total page 142 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book A Computational Study of Driven Micro cavities in Supersonic Flat Plate Flow

Download or read book A Computational Study of Driven Micro cavities in Supersonic Flat Plate Flow written by Thomas Ryan Rehmeier and published by . This book was released on 2013 with total page 110 pages. Available in PDF, EPUB and Kindle. Book excerpt: "Driven micro-cavities embedded in the wall beneath turbulent supersonic boundary layers are analyzed using two-dimensional computational fluid dynamics. This concept is a passive flow control technique in which very small cavities formed by arrays of thin vertical walls are oriented transverse to the flow direction and underlie the boundary layer. The purpose is to reduce or eliminate skin friction drag. Various micro-cavity configurations were analyzed at locations (0.1 m and 1 m) downstream of the leading edges of flat plates, for free-stream Mach numbers of 1.2, 2.0, and 3.0. Results focus on net drag reduction achieved, cavity flow-field effects, perforation effects in vertical cavity walls, cavity scale effects, mesh refinement issues, and the stability of the solutions. Skin friction drag was eliminated over micro-cavity regions for all configurations tested. Drag in these regions was due to pressure effects on vertical walls and exhibited a linear increase with downstream distance. Drag reductions as high as 18-20% (compared to a reference flat plate section) were obtained for 52-cavity geometries at Mach 2.0 and Mach 3.0 downstream of the 10 cm and 1 m flat plates, respectively. Perforation of the cavity walls showed no effect on net drag reduction for these cases. Stability issues were observed when using a fine grid mesh for the Mach 2.0 case, with significant oscillations seen in the drag. A parametric investigation in which cavity scale, number, and wall configuration were varied was also performed for two free-stream Mach numbers of 1.2 and 3.0. Drag reductions between 18-40% were seen for these cases. It is shown that drag reduction was reduced with increasing cavity length and that the steadiness of the solution increases with the number of vertical cavity walls present"--Abstract, page iii.

Book Experimental Investigation of Flow induced Cavity Resonance

Download or read book Experimental Investigation of Flow induced Cavity Resonance written by Paul Zoccola (Jr., J.) and published by . This book was released on 2000 with total page 200 pages. Available in PDF, EPUB and Kindle. Book excerpt: