Author: Eric J. DeMillard Publisher: ISBN: 9781085621250 Category : Fluid dynamics Languages : en Pages : 56
Book Description
Experimental investigations were carried out in both non-swirling and swirling jets at a Re = 105. A stereoscopic particle image velocimetry (SPIV) system was used to acquire the measurements in both axial-radial and radial-tangential planes at x/D = (1-10). Multiple test cases were taken where both the swirl magnitude and swirl distribution was adjusted. Proper Orthogonal Decomposition (POD) was then applied to the measurements to characterize turbulence structure. The results indicate that swirl causes the structure to be more ordered and shifts the relative amount of energy from axisymmetric structure to azimuthal structure.
Author: Sara Toutiaei Publisher: ISBN: 9781321238839 Category : Jets Languages : en Pages : 52
Book Description
In this study, velocity distributions of a swirling and a non-swirling jet flows were obtained using Laser Doppler Anemometer (LDA) in the near field where both jets are at the same stages of development. The resulting mean velocity and Reynolds stress distributions and the energy budgets of the axial Reynolds stresses are assessed. All Reynolds stresses showed higher magnitude in the swirling case compared to the non-swirling one at the same measurement axial locations. The swirling jet is found to exhibit larger production, mean convection and turbulence transport terms in the energy budget of axial Reynolds stress. The result shows faster development of the swirling jet compared with the non-swirling jet and is in consistency with previous studies. The turbulent transport term is found to be responsible for the faster development of the turbulence in the swirling jet.
Author: Jonathan Wayne Naughton Publisher: ISBN: Category : Eddies Languages : en Pages : 30
Book Description
Swirling jet flows have been studied experimentally and computationally and the results have been compared with theory. Three-component Laser Doppler Anemometry (LDA) measurements have been carried out for swirling jets of various strengths and swirl distributions. Radial profiles of velocity have been obtained from the jet exit to 50 diameters downstream. The experimental results are consistent with previous results and with similarity theory for weakly swirling turbulent jets. However, the parametric range and spatial domain of the current data set makes it suitable for validation. Computational simulations have also been performed using a combination of Reynolds Averaged Navier-Stokes (RANS) and Large Eddy Simulation (LES) approaches. The results have been validated with experimental data and used to explore the mechanisms behind the increased mixing enhancement observed. The combined experimental/computational effort is still ongoing, but the experiences to date have demonstrated the effectiveness of such an approach.
Author: Nenad Mitrovic Publisher: Springer Nature ISBN: 3030583627 Category : Technology & Engineering Languages : en Pages : 478
Book Description
This proceedings book is a collection of high-quality peer-reviewed research papers presented at the International Conference of Experimental and Numerical Investigations and New Technologies (CNNTech2020) held at Zlatibor, Serbia, from 29th June to 2nd July 2020. The book discusses a wide variety of industrial, engineering and scientific applications of the engineering techniques. Researchers from academia and industry present their original work and exchange ideas, experiences, information, techniques, applications and innovations in the field of mechanical engineering, materials science, chemical and process engineering, experimental techniques, numerical methods and new technologies.
Author: Ing Kiet Francis Toh Publisher: ISBN: Category : Jets Languages : en Pages : 247
Book Description
The mean flow properties and the instantaneous flow structures of the jets are then investigated. The introduction and increase of swirl result in a higher jet growth, decay and turbulent intensity, the formation of an off-axis axial velocity maximum and the occurrence of vortex breakdown. The swirl-induced jet growth enhancement can be categorized into three regimes: a low swirl regime in which there is a limited enhancement, a moderate swirl regime in which the enhancement scales with swirl, and a high swirl regime in which vortex breakdown dominates the process. The jet growth behavior in the high swirl regime is found to be dependent on the structure of the jet and the vortex breakdown configuration. A significant change in the flow structures and certain mean flow properties including the centerline and local maximum axial velocity decay are observed in the low and the moderate swirl regimes. These properties appear to be less sensitive to swirl in the high swirl regime after the occurrence of vortex breakdown. The effects of Reynolds number on swirling jets may not be identical to that on a non-swirling jet. The statistical characteristics measured show that low velocity occasions in the vicinity of the jet centerline start to appear at a sufficiently high degree of swirl. These occasions increase with swirl until the eventual occurrence of vortex breakdown. The statistical characteristics of jets that have undergone vortex breakdown are very similar, as they are dominated by the vortex breakdown phenomenon. The mean flow and the statistical measurements also reveal the presence of an unstable vortex breakdown that is difficult to detect using flow visualization and instantanous velocity field measurements.
Author: Jean Piquet Publisher: Springer Science & Business Media ISBN: 3662035596 Category : Technology & Engineering Languages : en Pages : 767
Book Description
obtained are still severely limited to low Reynolds numbers (about only one decade better than direct numerical simulations), and the interpretation of such calculations for complex, curved geometries is still unclear. It is evident that a lot of work (and a very significant increase in available computing power) is required before such methods can be adopted in daily's engineering practice. I hope to l"Cport on all these topics in a near future. The book is divided into six chapters, each· chapter in subchapters, sections and subsections. The first part is introduced by Chapter 1 which summarizes the equations of fluid mechanies, it is developed in C~apters 2 to 4 devoted to the construction of turbulence models. What has been called "engineering methods" is considered in Chapter 2 where the Reynolds averaged equations al"C established and the closure problem studied (§1-3). A first detailed study of homogeneous turbulent flows follows (§4). It includes a review of available experimental data and their modeling. The eddy viscosity concept is analyzed in §5 with the l"Csulting ~alar-transport equation models such as the famous K-e model. Reynolds stl"Css models (Chapter 4) require a preliminary consideration of two-point turbulence concepts which are developed in Chapter 3 devoted to homogeneous turbulence. We review the two-point moments of velocity fields and their spectral transforms (§ 1), their general dynamics (§2) with the particular case of homogeneous, isotropie turbulence (§3) whel"C the so-called Kolmogorov's assumptions are discussed at length.
Author: Eric J. DeMillard
Author: Sara Toutiaei
Author: Jonathan Wayne Naughton
Author: Rahmat Taghavi
Author: Michael S. Tsurikov
Author: Larry P. Marini
Author: Nenad Mitrovic
Author: Ing Kiet Francis Toh
Author: Jean Piquet
Author: Zahir Uddin Ahmed