Experimental and Numerical Study of Impingement Jet Heat Transfer

Experimental and Numerical Study of Impingement Jet Heat Transfer
Author: Andrew Urban Schroder
Publisher:
Total Pages: 217
Release: 2011
Genre:
ISBN:

An experimental test facility has been designed, constructed, and commissioned for studying the convective heat transfer of an array of 55 impingement jets. Spatial variation in time averaged Nusselt number as well as spanwise time averaged Nusselt number are presented for jet Reynolds numbers of 4,000, 8,000, 12,000, and 15,000 for jet to target standoff distances of z/D=3, 4, and 5. For each of these configurations the exit flow configuration has also been varied to include both a single exit and double exit configuration. For each jet standoff distance and exit configuration, time and overall area averaged Nusselt number is presented as a function of jet Reynolds number. Animations of measured unsteady Nusselt number are presented for selected cases. Numerical simulations have been conducted using the Fluent Computational Fluid Dynamics software package. The three dimensional, compressible, Navier Stokes equations are solved. Results for Nusselt number are presented for a grid dependency study of a steady, single impingement jet impacting a target surface at a standoff distance of z/D=3, at jet Reynolds numbers of 4,000 and 15,000. In the single jet grid dependency study flow is exhausted in all directions after impacting the target surface. Grids ranging from 1.2 million to 13.2 million grid points are evaluated. Unsteady simulations were conducted of a single impingement jet at a jet Reynolds number of 4000, a jet to target standoff distance of z/D=3, flow exiting in two directions, and a pair of repeating boundaries in the other two directions. Two cases were studied. The first with a spacing between the two repeating boundaries of y/D=6 and the second with a spacing of y/D=3. For both cases, contour plots of time averaged, as well as animations of unsteady in plane velocity magnitude, normal component of vorticity, and Nusselt number are presented. Unsteady simulations were also conducted of eleven impingement jets at a jet Reynolds number of 4,000, a jet to target standoff distance of z/D=3, and a double exit configuration. Two cases were studied. The first with a spacing between the two repeating boundaries of y/D=4.03 and the second with a spacing of y/D=3. For both cases, contour plots of time averaged in plane velocity magnitude, normal component of vorticity, pressure, temperature, and Nusselt number are presented. Animations of contours of in plane velocity magnitude, normal component of vorticity, and Nusselt number are also presented. Spanwise time average Nusselt number for both eleven jet numerical cases is compared to that of the central row of an experimental case with a double exit configuration. Comparisons are also made between spanwise average Nusselt number for the central jet of an experimental case, a single jet numerical, the single jet numerical cases with the repeating boundaries, as well as the central jet of the eleven jet numerical cases.

Advances in Heat Transfer

Advances in Heat Transfer
Author:
Publisher: Academic Press
Total Pages: 467
Release: 1998-05-18
Genre: Technology & Engineering
ISBN: 0080575846

Advances in Heat Transfer

Impingement Jet Cooling in Gas Turbines

Impingement Jet Cooling in Gas Turbines
Author: R.S. Amano
Publisher: WIT Press
Total Pages: 253
Release: 2014-05-28
Genre: Science
ISBN: 1845649060

Due to the requirement for enhanced cooling technologies on modern gas turbine engines, advanced research and development has had to take place in field of thermal engineering. Among the gas turbine cooling technologies, impingement jet cooling is one of the most effective in terms of cooling effectiveness, manufacturability and cost. The chapters contained in this book describe research on state-of-the-art and advanced cooling technologies that have been developed, or that are being researched, with a variety of approaches from theoretical, experimental, and CFD studies. The authors of the chapters have been selected from some of the most active researchers and scientists on the subject. This is the first to book published on the topics of gas turbines and heat transfer to focus on impingement cooling alone.

Mechanical Measurements

Mechanical Measurements
Author: S.P. Venkateshan
Publisher: Springer Nature
Total Pages: 560
Release: 2021-07-01
Genre: Technology & Engineering
ISBN: 3030736202

p="" This book focuses both on the basics and more complex topics in mechanical measurements such as measurement errors & statistical analysis of data, regression analysis, heat flux, measurement of pressure, and radiation properties of surfaces. End of chapter problems, solved illustrations, and exercise problems are presented throughout the book to augment learning. It is a useful reference for students in both undergraduate and postgraduate programs. ^

Experimental and Numerical Investigation of Heat and Mass Transfer Due to Pulse Combustor Jet Impingement

Experimental and Numerical Investigation of Heat and Mass Transfer Due to Pulse Combustor Jet Impingement
Author: Michael J. Psimas
Publisher:
Total Pages:
Release: 2010
Genre: Drying apparatus
ISBN:

Under certain circumstances pulse combustors have been shown to improve both heat transfer and drying rate when compared to steady flow impingement. Despite this potential, there have been few investigations into the use of pulse combustor driven impingement jets for industrial drying applications. The research presented here utilized experimental and numerical techniques to study the heat transfer characteristics of these types of oscillating jets when impinging on solid surfaces and the heat and mass transfer when drying porous media. The numerical methods were extensively validated using laboratory heat flux and drying data, as well as correlations from literature. As a result, the numerical techniques and methods that were developed and employed in this work were found to be well suited for the current application. It was found that the pulsating flows yielded elevated heat and mass transfer compared to similar steady flow jets. However, the numerical simulations were used to analyze not just the heat flux or drying, but also the details of the fluid flow in the impingement zone that resulted in said heat and mass transport. It was found that the key mechanisms of the enhanced transfer were the vortices produced by the oscillating flow. The characteristics of these vortices such as the size, strength, location, duration, and temperature, determined the extent of the improvement. The effects of five parameters were studied: the velocity amplitude ratio, oscillation frequency, the time-averaged bulk fluid velocity at the tailpipe exit, the hydraulic diameter of the tailpipe, and the impingement surface velocity. Analysis of the resulting fluid flow revealed three distinct flow types as characterized by the vortices in the impingement zone, each with unique heat transfer characteristics. These flow types were: a single strong vortex that dissipated before the start of the next oscillation cycle, a single persistent vortex that remained relatively strong at the end of the cycle, and a strong primary vortex coupled with a short-lived, weaker secondary vortex. It was found that the range over which each flow type was observed could be classified into distinct flow regimes. The secondary vortex and persistent vortex regimes were found to enhance heat transfer. Subsequently, transition criteria dividing these regimes were formed based on dimensionless parameters. The critical dimensionless parameters appeared to be the Strouhal number, a modified Strouhal number, the Reynolds number, the velocity amplitude ratio, and the H/Dh ratio. Further study would be required to determine if these parameters offer similar significance for other configurations.

Experimentation, Validation, and Uncertainty Analysis for Engineers

Experimentation, Validation, and Uncertainty Analysis for Engineers
Author: Hugh W. Coleman
Publisher: John Wiley & Sons
Total Pages: 404
Release: 2018-04-09
Genre: Technology & Engineering
ISBN: 1119417708

Helps engineers and scientists assess and manage uncertainty at all stages of experimentation and validation of simulations Fully updated from its previous edition, Experimentation, Validation, and Uncertainty Analysis for Engineers, Fourth Edition includes expanded coverage and new examples of applying the Monte Carlo Method (MCM) in performing uncertainty analyses. Presenting the current, internationally accepted methodology from ISO, ANSI, and ASME standards for propagating uncertainties using both the MCM and the Taylor Series Method (TSM), it provides a logical approach to experimentation and validation through the application of uncertainty analysis in the planning, design, construction, debugging, execution, data analysis, and reporting phases of experimental and validation programs. It also illustrates how to use a spreadsheet approach to apply the MCM and the TSM, based on the authors’ experience in applying uncertainty analysis in complex, large-scale testing of real engineering systems. Experimentation, Validation, and Uncertainty Analysis for Engineers, Fourth Edition includes examples throughout, contains end of chapter problems, and is accompanied by the authors’ website www.uncertainty-analysis.com. Guides readers through all aspects of experimentation, validation, and uncertainty analysis Emphasizes the use of the Monte Carlo Method in performing uncertainty analysis Includes complete new examples throughout Features workable problems at the end of chapters Experimentation, Validation, and Uncertainty Analysis for Engineers, Fourth Edition is an ideal text and guide for researchers, engineers, and graduate and senior undergraduate students in engineering and science disciplines. Knowledge of the material in this Fourth Edition is a must for those involved in executing or managing experimental programs or validating models and simulations.

Advances in Heat Transfer and Thermal Engineering

Advances in Heat Transfer and Thermal Engineering
Author: Chuang Wen
Publisher: Springer Nature
Total Pages: 914
Release: 2021-06-01
Genre: Science
ISBN: 9813347651

This book gathers selected papers from the 16th UK Heat Transfer Conference (UKHTC2019), which is organised every two years under the aegis of the UK National Heat Transfer Committee. It is the premier forum in the UK for the local and international heat transfer community to meet, disseminate ongoing work, and discuss the latest advances in the heat transfer field. Given the range of topics discussed, these proceedings offer a valuable asset for engineering researchers and postgraduate students alike.

Numerical Analysis of Heat Transfer During Jet Impingement on Curved Surfaces

Numerical Analysis of Heat Transfer During Jet Impingement on Curved Surfaces
Author: Cesar F. Hernandez-Ontiveros
Publisher:
Total Pages:
Release: 2007
Genre:
ISBN:

ABSTRACT: The flow structure and convective heat transfer behavior of a free liquid jet ejecting from a round nozzle impinging vertically on a hemispherical solid plate and a slot nozzle impinging vertically on a cylindrical curved plate have been studied using a numerical analysis approach. The simulation model incorporated the entire fluid region and the solid hemisphere or curved plate. Solution was done for both isothermal and constant heat flux boundary conditions at the inner surface of the hemispherical plate and the constant heat flux boundary condition at the inner surface of the cylindrical shaped plate. Computations for the round nozzle impinging jet on the hemispherical plate and cylindrical plate were done for jet Reynolds number (ReJ) ranging from 500 to 2000, dimensionless nozzle to target spacing ratio (β) from 0.75 to 3, and for various dimensionless plate thicknesses to diameter nozzle ratio (b/dn) from 0.083-1.5. Also, computations for the slot nozzle impinging jet on the cylindrical plate were done for inner plate radius of curvature to nozzle diameter ratio (Ri/dn) of 4.16-16.66, plate thickness to nozzle diameter ratio (b/dn) of 0.08-1.0, and different nozzle diameters (dn), Results are presented for dimensionless solid-fluid interface temperature, dimensionless maximum temperature in the solid, local and average Nusselt numbers using the following fluids: water (H2O), flouroinert (FC-77), and oil (MIL-7808) and the following solid materials: aluminum, copper, Constantan, silver, and silicon. Materials with higher thermal conductivity maintained a more uniform temperature distribution at the solid-fluid interface. A higher Reynolds number increased the Nusselt number over the entire solid-fluid interface. Local and average Nusselt number and heat transfer coefficient distributions showed a strong dependence on the impingement velocity or Reynolds number. As the velocity increases, the local Nusselt number increases over the entire solid-fluid interface. Decreasing the nozzle to target spacing favors the increasing of the Nusselt number. Increasing the nozzle diameter decreases the temperature at the curved plate outer surface and increases the local Nusselt number. Similarly, local and average Nusselt number was enhanced by decreasing plate thickness. Numerical simulation results are validated by comparing with experimental measurements and related correlations.

Food Engineering: Integrated Approaches

Food Engineering: Integrated Approaches
Author: Gustavo F. Gutiérrez-Lopez
Publisher: Springer Science & Business Media
Total Pages: 475
Release: 2008-02-29
Genre: Technology & Engineering
ISBN: 038775430X

This book presents a significant and up-to-date review of various integrated approaches to food engineering. Distinguished food engineers and food scientists from key institutions worldwide have contributed chapters that provide a deep analysis of their particular subjects. Emerging technologies and biotechnology are introduced, and the book discusses predictive microbiology, packing materials for foods, and biodegradable films. This book is mainly directed to academics, and to undergraduate and postgraduate students in food engineering and food science and technology, who will find a selection of topics.