Experimental Investigation of Twin and Triple Elliptic Free Jets with Various Nozzle Orientations PDF Download
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Author: Ella Morris
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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Book Description
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.
Author: Ella Morris
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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Book Description
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.
Author: Suvanjan Bhattacharyya
Publisher: Springer Nature
ISBN: 9811962707
Category : Science
Languages : en
Pages : 628
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Book Description
This book presents the select proceedings of the 48th National Conference on Fluid Mechanics and Fluid Power (FMFP 2021) held at BITS Pilani in December 2021. It covers the topics such as fluid mechanics, measurement techniques in fluid flows, computational fluid dynamics, instability, transition and turbulence, fluid‐structure interaction, multiphase flows, micro- and nanoscale transport, bio-fluid mechanics, aerodynamics, turbomachinery, propulsion and power. The book will be useful for researchers and professionals interested in the broad field of mechanics.
Author: Eugene P. Symons
Publisher:
ISBN:
Category : Laminar flow
Languages : en
Pages : 28
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Book Description
An experimental investigation was conducted to determine dynamic characteristics of a circular, fully developed, laminar free jet. Complete velocity profiles are presented at Reynolds numbers of 437 and 1839 at 0, 3, 6, 10, 15, and 25 diameters from the nozzle exit. Centerline velocity decay was obtained over a range of Reynolds numbers from 255 to 1839. Also presented are the angles of spread associated with the diffusion of the jet downstream of the nozzle. Where possible, results are compared with those obtained for laminar jets having an initially flat or uniform velocity profile at the nozzle exit.
Author: Chidiebere Felix Nwaiwu
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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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.
Author: Allen R. Vick
Publisher:
ISBN:
Category : Aerodynamics
Languages : en
Pages : 70
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Author: Ebenezer Essel
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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Book Description
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.
Author: Hyder S. Husain
Publisher:
ISBN:
Category : Jets
Languages : en
Pages : 376
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Author:
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Author: Duygu Erdem
Publisher:
ISBN:
Category :
Languages : en
Pages :
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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. .
Author: Leijun Li
Publisher: Springer Nature
ISBN: 9811513074
Category : Technology & Engineering
Languages : en
Pages : 643
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Book Description
This book gathers outstanding papers presented at the International Conference on Advances in Materials and Manufacturing Engineering (ICAMME 2019), held at KIIT Deemed to be University, Bhubaneswar, India, from 15 to 17 March 2019. It covers theoretical and empirical developments in various areas of mechanical engineering, including manufacturing, production, machine design, fluid/thermal engineering, and materials.
