Download or read book An Experimental Study on Rectangular Twin Jets written by Duygu Erdem and published by . This book was released on 2001 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Interaction of two incompressible rectangular jets and impingement of twin jets on a flat surface are investigated experimentally in the present study. Five different twin jet geometries are used to perform the measurements.Detailed analysis of initial flow characteristics as the initial boundary layer,turbulence level and the initial spectral distribution of the velocity fluctuations are presented first. Twin jet flow characteristics are examined by using three different Reynolds numbers based on the nozzle exit height. Flow pattern is investigated on lateral and spanwise directions. Following the twin jet experiments, results are compared with those of offset jet flow. Then, the effect of a convex surface between two jet exits on the flow development is examined.Twin jet impingement on a flat surface is investigated. To examine the effect of the non-dimensional nozzle to plate distance (Y /H+) on the flow , experiments are performed for three different nozzle to plate distances (Y/H+=2, 4, 8). Resultant velocity and turbulence intensity profiles and pressure distributions on the plate are measured.The mean velocity and turbulence intensities are measured by using constanttemperature hot-wire anemometry. Flow visualization techniques as smokevisualization and surface oil film technique are used for qualitative investigation of flow pattern. Pressure distributions on the impingement plate are measured by means of the pressure tabs on the surface and a micro manometer.This study consists of five chapters. Chapter 1 is the introduction which outlines the objectives and the means of the study. Chapter 2 describes basic principles of the turbulent, incompressible jet flow structure and gives literature review of the experimental studies and recent advances on the characteristics of the flow. Experimental flow facility , instrumentation and experimental procedures are described in Chapter 3. Experimental results are presented in Chapter 4. Finally, conclusions are given in Chapter 5. .

Download or read book An Experimental Study of Rectangular Surface Jets written by Soheil Gholamreza-Kashi and published by . This book was released on 2006 with total page 372 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Experimental Study of Submerged Turbulent Twin Jets Interacting with a Free Surface and a Solid Wall written by Ebenezer Essel and published by . This book was released on 2018 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis presents an experimental investigation of the effects of offset height ratio and boundary condition (free surface and solid wall) on the turbulence characteristics of submerged twin jets issuing from two parallel round nozzles. A particle image velocimetry (PIV) technique was used to conduct two sets of experiments. The first set of experiments focused on twin surface jets at Reynolds number, Re = 4400, separation ratio (G/d = 2.3) and offset heights, 1d, 2d, 3d and 4d from the free surface. The second set of experiments, which was designed based on the main findings of the previous experiment, examined the effects of free surface and wall on the turbulence structure of the twin jets. These experiments were performed at Re = 5000, G/d = 2 and offset heights, 1d, 2d and 4d from the free surface or wall. For the surface jets, the mean velocity and turbulence intensities at the free surface rapidly increased beyond the attachment point by amounts that increases with decreasing offset ratio. Further downstream, the surface transverse turbulence intensities decayed to negligible values while the streamwise turbulence intensities were persistent because of the energy redistribution from the transverse Reynolds normal stress to the tangential (streamwise and spanwise) Reynolds stresses. For both boundary conditions, the attachment length, Reynolds stresses and the spatial extents of the large-scale structures increased with increasing offset ratio. The transition of the twin jets to a single jet was more rapid as offset ratio increases due to the enhanced entrainment and mixing for larger offset ratios. The evolution of the jet farther away from the free surface or wall behaved like a free jet, but the decay rate of the jet interacting with each boundary was substantially reduced in the far field due to confinement effects. The difference between the effects of free surface and wall on the mean velocity, Reynolds stresses and triple velocity correlations were confined to the immediate vicinity of each boundary. The interaction between the large-scale structures and the boundaries were also investigated using various multi-point statistical techniques such as discrete wavelet transform, linear stochastic estimation, swirling strength, joint probability density function and two-point velocity correlations. The results showed that, the wall considerably reduced the spatial coherence of the structures embodied in the transverse auto-correlations compared to those near the free surface.

Download or read book An Experimental Study of Multiple Jet Mixing written by Anjaneyulu Krothapalli and published by . This book was released on 1979 with total page 174 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book A Theoretical and Experimental Study of Twin Jet Interaction written by Mohammad Shamsul Alam and published by . This book was released on 1967 with total page 444 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Experimental Study of Spreading of Semi confined Jets turbulent Mixing Between Flat Plates of a Submerged Jet Formed by Rectangular Cross Section Nozzle with Particular Emphasis on Applications in Fluidics written by Roberto Bettoli and published by . This book was released on 1968 with total page 88 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Experimental Investigation of Nozzle Geometry Effect on the Characteristics and Structure of Submerged Twin Jets written by Chidiebere Felix Nwaiwu and published by . This book was released on 2020 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The effects of nozzle geometry on the mean and turbulent characteristics of submerged twin jets were experimentally investigated. The experiments were conducted at fixed Reynolds number and offset height ratio of 4,400 and h⁄d=2, respectively. The jets were produced from three nozzle geometries: round, square, and rectangle, with the rectangular nozzle geometry oriented in the minor (rect_min) and major (rect_maj) planes. The twin nozzles of each geometry type were aligned parallel to the free surface, and the separation ratio between the twin jets was fixed at G⁄d=2.3 for all cases. Velocity measurements were obtained using a particle image velocimetry (PIV) technique, and analyses of various quantities such as the instantaneous, mean, and surface velocities, as well as the turbulent statistics were performed. The jet-free surface interaction was examined using mean and turbulent surface velocities at the free surface, velocity defect, and vorticity thickness. Two-point velocity correlation and joint probability density function revealed the dynamics of the turbulent structures. Results from the velocity contours showed that the shear layer expansion was most rapid in twin jets produced from the rect_min nozzle geometry, which resulted in the shortest attachment length to the free surface. The instantaneous velocity field showed the most prograde and retrograde vortices in the rect_min nozzle geometry, accounting for the fastest shear layer expansion. Surface-normal profiles of the Reynolds stress ratio showed an enhancement of about 60% at the free surface and that the Townsend structure parameter was dependent on nozzle geometry. The mean surface velocity revealed that the free surface was in a state of strain due to alternating velocity gradient and was most intense in the rect_min jet. Large-scale structures produced along the centreline of the jet father away from the free surface (jet B) showed a larger streamwise extent compared to those along the centreline of the jet closer to the free surface (jet A) and were independent of nozzle geometry. Analysis of the joint probability density function of the streamwise and surface-normal velocity fluctuations showed that within the shear layer, the Reynolds shear stress producing events were dominated by slow entrainment and fast ejection events, and the damping effect of the free surface was least on the rect_min jets.

Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1975 with total page 978 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Basic Studies of Multiple Jets and Wall Jets written by A. Krothapalli and published by . This book was released on 1980 with total page 23 pages. Available in PDF, EPUB and Kindle. Book excerpt: An experimental investigation of the flow field of an underexpanded rectangular jet issuing from a rectangular nozzle of aspect ratio 16.7 was undertaken. Tests were conducted for pressure ratios (settling chamber pressure/ambient pressure) ranging from 1.6 to 5.8. For pressure ratios greater than 1.9 the spectrum of the hot wire and microphone signals placed in the near field of the jet show discrete frequencies generally known as screech tones. At a pressure ratio of 3.7, Schlieren pictures show a distinct double wave pattern with their source bing located at about 6 widths downstream. This results in an enhanced spreading of the jet as compared with other pressure ratios. A series of experiments on unconfined multiple jets has been performed for pressure ratios ranging from 1.6 to 3.7. Schlieren pictures were obtained which shows that the individual jets do not attract each other and mixing with the ambient air (or secondary air) takes place quite independently. The importance of sound waves (generated in one of the jets) acting upon the neighboring jets is demonstrated. Using this technique, it is shown that the mixing can be enhanced. (Author).

Download or read book Experimental Investigation of Twin and Triple Elliptic Free Jets with Various Nozzle Orientations written by Ella Morris and published by . This book was released on 2020 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The effects of nozzle orientation on the mixing and turbulent characteristics of elliptical free triple and twin jets were studied experimentally. The experiments were conducted using modified contoured nozzles with a sharp linear contraction. The centers of the nozzle pair had a separation ratio of s/d = 5.5 for twin jets and s/d = 4.1 for triple jets. For the twin-jet system, two nozzle configurations were tested, twin nozzles oriented along the minor plane (Twin_Minor) and twin nozzles oriented along the major plane (Twin_Major) and the results were compared with single jet. For the triple-jets system, three nozzle configurations were tested. The first configuration had each nozzle oriented along the minor plane (3_Minor), the next had two nozzles oriented along the minor plane and one along the major plane (Min_Maj_Min) and the last configuration had one nozzle oriented along the minor plane and two along the major plane (Maj_Min_Maj). In each case, the Reynolds number based on the maximum jet velocity and the equivalent diameter was 10,000. A planar particle image velocimetry system was used to measure the velocity field in the jet symmetry plane. The velocity decay, jet spread, merging point, combined point and potential core length were used to characterize the effects of nozzle orientation on the mixing performance. For both twin jets and triple jets, it was observed that the velocity decay rate is not sensitive to nozzle orientation. However, the spread rate was approximately 35% higher in the minor plane for each configuration. In addition, the potential core length for 3_Minor was approximately 42% shorter than Twin_Minor. Furthermore, contour plots of swirling strength, Reynolds shear stress and turbulent intensities revealed significant differences between the minor and major plane for both twin and triple jets. One-dimensional plots revealed that jets approached self-similarity at a faster rate in the major axis.

Download or read book Experimental Study of Asymmetric Parallel Jets written by E. A. Anderson and published by . This book was released on 2003 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book On the Effects of Nozzle Spacing Ratio on Statistical Properties of Twin Low aspect ratio Rectangular Jets written by Ramin Naseri Oskouie and published by . This book was released on 2020 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: An experimental study was performed to investigate the effects of the spacing ratio between the nozzles on the evolution and interaction of twin rectangular jets. The velocity measurements were conducted using particle image velocimetry (PIV) technique. The measurements were performed on the symmetry plane of the rectangular jets. A total of 5 test cases of S/de = 1.8, 2.8, 3.7, 5.5 and 7.3 were examined with Reynolds number being fixed and equal to Rede = 10,000. The effects of the spacing ratio on the mean flow in terms of its mixing characteristics (e.g., decay and spread rates) and turbulence statistics (e.g., turbulence intensities and Reynolds stresses) were investigated. The focus was then on large-scale structures (LSS). The evolution of LSS was studied along the shear layers and the symmetry line in order to investigate the effects of nozzle spacing and interactions. For doing so, various techniques such as Galilean decomposition, two-point correlation and swirling strength were applied on the flow field. The conditionally-averaged mean streamwise velocity profiles were also extracted around the turbulent/non-turbulent interface (TNTI) and results were compared with twin round jet counterpart. The results showed that changing the spacing ratio directly affects some characteristics of the mean flow, turbulence statistics and LSS. For instance, it was observed that increasing the spacing ratio, linearly increases the streamwise locations of the merging and combined points though with different slopes. Turbulence intensity profiles along the symmetry line showed a peak downstream of the merging point, where its value decreased as the spacing ratio increased. Also, interestingly for S/de ≤ 3.7, the peak of the transverse component was larger than the streamwise component. Regarding the integral length scale of turbulence along the symmetry line, a linearly increasing trend was observed. Whilst no effects of nozzle spacing was observed on the streamwise component, the trend for the transverse component showed to increase by increasing the spacing ratio. Due to the importance of the shear layers in free shear flows, a special attention was paid to the inner and outer shear layers. In the converging region, jet half-velocity widths were identical for the shear layers. In the merging region however, while the outer shear layer continued to spread similarly to its single jet counterpart, the half-velocity width of the inner shear layer rapidly increased before becoming unstable by the interactions. Study of coherent structures showed that the effects of interactions become more pronounced as the inner shear layer develops in the merging region. For instance, 0.1de downstream of the merging point, the streamwise spatial correlation of the outer and inner shear layers were identical. By progressing into the merging region however, this reduced for the inner shear layer while expectedly increased for the outer shear layer. In a similar fashion, at the TNTI the difference between conditionally- and unconditional- averaged profiles of mean streamwise velocity increased as the inner shear layer developed in the merging region. As a result, the conditional profile jumped to a larger value upon entering the turbulent region.

Download or read book Proceedings of XXIV AIMETA Conference 2019 written by Antonio Carcaterra and published by Springer Nature. This book was released on 2020-03-31 with total page 2200 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book gathers the peer-reviewed papers presented at the XXIV Conference of the Italian Association of Theoretical and Applied Mechanics, held in Rome, Italy, on September 15-19, 2019 (AIMETA 2019). The conference topics encompass all aspects of general, fluid, solid and structural mechanics, as well as mechanics for machines and mechanical systems, including theoretical, computational and experimental techniques and technological applications. As such the book represents an invaluable, up-to-the-minute tool, providing an essential overview of the most recent advances in the field.

Download or read book An Experimental Study of Multiple Jet Mixing written by and published by . This book was released on 1979 with total page 174 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Experimental Studies on Flow and Noise Generated from Single and Twin Supersonic Underexpanded Jets written by Alireza Roshanzamir and published by . This book was released on 1994 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1988 with total page 1142 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book An Experimental Study of Plane Jets Issuing at Various Angles Into a Cross flow written by Constantine Hadjilambrinos and published by . This book was released on 1986 with total page 150 pages. Available in PDF, EPUB and Kindle. Book excerpt: