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Book AIAA 90 1521 AIAA 90 1569

Download or read book AIAA 90 1521 AIAA 90 1569 written by and published by . This book was released on 1990 with total page 514 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Experimental Investigation of Turbulent Boundary Layer with Uniform Blowing at Moderate and High Reynolds Numbers

Download or read book Experimental Investigation of Turbulent Boundary Layer with Uniform Blowing at Moderate and High Reynolds Numbers written by Gazi Hasanuzzaman and published by Cuvillier Verlag. This book was released on 2022-01-18 with total page 180 pages. Available in PDF, EPUB and Kindle. Book excerpt: Experimental investigation in turbulent boundary layer flows represents one of the canonical geometries of wall bounded shear flows. Utmost relevance of such experiments, however, is applied in the engineering applications in aerospace and marine industries. In particular, continuous effort is being imparted to explore the underlying physics of the flow in order to develop models for numerical tools and to achieve flow control. Flow control experiments have been widely investigated since 1930’s. Several flow control technique has been explored and have shown potential benefit. But the choice of control technique depends largely on the boundary condition and the type of application. Hence, friction drag of subsonic transport aircraft is intended to be reduced within the scope of this Ph. D. topic. Therefore, application of active control method such as microblowing effect in the incompressible, zero pressure gradient turbulent boundary layer was investigated. A series of experiments have been performed in two different wind tunnel facilities. Wind tunnel from Department of Aerodynamics and Fluid Mechanics (LAS) was used for the measurements for moderate Reynolds number range in co-operation with the wind tunnel from Laboratoire de M´ecanique de Feiret Lille for large Reynolds number range. Measurements are conducted with the help of state-of-the-art techniques such as Laser Doppler Anemometry, Particle Image Velocimetry and electronic pressure sensors.

Book Previews of Heat and Mass Transfer

Download or read book Previews of Heat and Mass Transfer written by and published by . This book was released on 1989 with total page 632 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Experimental Investigation of the Flow Around Struts in Boundary Layers

Download or read book Experimental Investigation of the Flow Around Struts in Boundary Layers written by W. F. Glasspoole and published by . This book was released on 1959 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book An Experimental Investigation of the Flow Structure of the Turbulent Boundary Layer

Download or read book An Experimental Investigation of the Flow Structure of the Turbulent Boundary Layer written by P. W. Runstadler and published by . This book was released on 1963 with total page 346 pages. Available in PDF, EPUB and Kindle. Book excerpt: A combination of visual and quantitative measurements is presented, providing a physical picture of the turbulent boundary layer flow structure on a flat plate. The flow structure is shown to consist of three zones, each zone has a one to one correspondence to the well known regions of the u+, y+ mean velocity profile. A wall layer region is shown to exist below y+ = 10. An apparently fully turbulent region exists corresponding to the logarithmic ''law of the wall'' and the ''buffer'' region. An intermittent zone appears to agree closely with the ''wake'' deviation region. An entirely new result of the investigation is the delineation of the structure of the wall layer region. This region is shown to contain a relatively regular structure of low and high velocity fluid streaks alternating in the span direction, together with the ejection of low momentum fluid into the outer flow. Correlations are given for the rate of ejection and the streak spacing. A qualitative description of other features of the wall layer region and the character of the remainder of the boundary layer flow structure is presented. (Author).

Book 25th AIAA Fluid Dynamics Conference

Download or read book 25th AIAA Fluid Dynamics Conference written by and published by . This book was released on 1994 with total page 584 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Experimental Investigation of Turbulent Flow Field and Pressure Fluctuations on Flat Surfaces and Cylinders

Download or read book Experimental Investigation of Turbulent Flow Field and Pressure Fluctuations on Flat Surfaces and Cylinders written by William W. Willmarth and published by . This book was released on 1987 with total page 23 pages. Available in PDF, EPUB and Kindle. Book excerpt: The structure of the fluctuating flow field in a turbulent boundary layer has been investigated with the aid of extremely small hot wire probes. Two investigations were conducted. In one investigations of a small X array hot-wire probe, with dimensions (length and spacing) of the order of 2.5 viscous lengths (100 Microns) was constructed and used to measure the small scale structure of the velocity fluctuations and the Reynolds stress near the wall. It was found that very small, intense contributions to the Reynolds stress occur with a scale of the order of the viscous length. In the other investigation a pair of single hot-wires which were of a length of the order of one half the viscous length (50 Microns) were used to demonstrate the existence of shear layers near the wall with an intensity comparable to the mean shear stress at the wall. One primary results is when large scale turbulence is present in the flow upstream of the cylinder, large amplitude, low frequency circumferentially averaged pressure fluctuations are caused by pressure fluctuations in the free stream turbulence and by the aerodynamic interaction of cylinder with the free stream turbulence. A three-sensor hot-wire probe was used to measure the three components of the velocity fluctuations in the free stream at a point 3.5 diameters from the axis of the cylinder. When the free stream turbulence level was low, the instantaneous average of the pressure fluctuations around the circumference could be estimated from the free stream velocity fluctuations near the measuring point on the cylinder.

Book Experimental Study of Wall Proximity Effects on Turbulent Flow Around a Square Cylinder

Download or read book Experimental Study of Wall Proximity Effects on Turbulent Flow Around a Square Cylinder written by Samuel Addai and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis presents an experimental investigation on turbulent flow around a square cylinder at a finite distance from a smooth wall. The turbulent boundary layer thickness was 3.6 times the cylinder height (h) while the Reynolds number based on the free-stream velocity and the cylinder height was 12750. The gap distance (G) between the bottom face of the cylinder and the wall was varied, resulting in gap ratios of G⁄h= 0, 0.3, 0.5, 1.0, 2.0, 4.0 and 8.0. A two-dimensional, two-component time-resolved particle image velocimetry system was used to perform velocity measurements in both double frame and high-speed modes. Wall proximity effects on the mean flow, Reynolds stresses, triple velocity correlations and two-point autocorrelations were examined. Premultiplied frequency spectra of velocity fluctuations, temporal autocorrelations, reverse flow area and proper orthogonal decomposition (POD) were employed to investigate the unsteadiness of the separated shear layers and the wake flow. The results indicated that as gap ratio decreases, asymmetry in the wake region becomes more pronounced and the size of the mean recirculation bubbles in the cylinder wake increases. Meanwhile, the Kelvin-Helmholtz vortical structures in the separated shear layers decreased in size as the cylinder approached the wall. With decreasing gap ratio, the magnitudes of the Reynolds stresses and triple velocity correlations generally decreased but the wake width and vortex formation length increased. Also, the size of the large-scale structures and the integral time scales increased with decreasing gap ratio. The critical gap ratio, below which the von Kármán vortex shedding is suppressed, was found to be 0.3. The dominant Strouhal numbers of the Kelvin-Helmholtz and von Kármán instabilities, expressed in terms of the free-stream velocity, were observed to be insensitive to gap ratio. However, the von Kármán Strouhal number, expressed in terms of the mean streamwise velocity at the cylinder vertical midpoint, increased as gap ratio decreased. Furthermore, the reverse flow area displayed temporal fluctuations and its dominant Strouhal number decreased with decreasing gap ratio. From the POD analysis, the first two POD modes were found to be the most dominant, but their correlation weakened as gap ratio decreased.

Book International Aerospace Abstracts

Download or read book International Aerospace Abstracts written by and published by . This book was released on 1998 with total page 920 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book An Experimental Investigation of the Interaction of a Developing Turbulent Flow with a Longitudinally Resonant Acoustic Field in a Horizontal Pipe

Download or read book An Experimental Investigation of the Interaction of a Developing Turbulent Flow with a Longitudinally Resonant Acoustic Field in a Horizontal Pipe written by Kent Charles Williams and published by . This book was released on 1969 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Scientific and Technical Aerospace Reports

Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1994 with total page 892 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book NASA Technical Memorandum

Download or read book NASA Technical Memorandum written by and published by . This book was released on 1994 with total page 492 pages. Available in PDF, EPUB and Kindle. Book excerpt: