Download or read book A Numerical Simulation of the Flow Field and Heat Transfer in a Rectangular Duct with a Turbulator Using a Predictor corrector Algorithm written by Bryan.R. Becker and published by . This book was released on 1988 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book A Numerical Simulation of the Flow Field and Heat Transfer in a Rectangular Passage with a Turbulence Promoter written by and published by . This book was released on 1988 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: A numerical study of the flow field and heat transfer in a turbine blade control cooling passage is described. Attention is focused on a short straight section of the rectangular passage which includes a single turbulator protruding from its floor. The two dimensional, transient, Reynolds averaged Navier Stokes, continuity and energy equations are iterated to a steady state solution using the MacCormick explicit predictor-corrector algorithm. Turbulence closure is achieved through the use of the Baldwin-Lomax form of the Cebeci-Smith algebraic two layer eddy viscosity model. Plots of skin friction, local heat transfer rate, streamlines, velocity profiles and temperature profiles are given. It was found that the widely used Reynolds Analogy greatly underpredicts the heat transfer rate as given by a direct calculation using Fourier's law. Keywords: Heat transfer, Turbulence augmentation. (mjm).
Download or read book AIAA ASME SAE ASEE 24th Joint Propulsion Conference written by and published by . This book was released on 1988 with total page 450 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book International Aerospace Abstracts written by and published by . This book was released on 1988 with total page 764 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Computation of the Flow Field and Heat Transfer in a Rectangular Passage with a Turbulator written by Bryan R. Becker and published by . This book was released on 1989 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Direct Numerical Simulation of Turbulent Flow and Heat Transfer in a Square Duct Roughened with Transverse Or V shaped Ribs written by Seyyed Vahid Mahmoodi Jezeh and published by . This book was released on 2021 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: This integrated thesis documents a series of complementary numerical investigations aimed at an improved understanding of turbulent flows and heat transfer in a square duct with ribs of different shapes mounted on one wall. Direct numerical simulation (DNS) is used to accurately resolve the spatial and temporal scales of the simulated flows. The first DNS investigates the turbulent flow in a ribbed square duct of different blockage ratios. The results are compared with those of a smooth duct flow. It is observed that an augmentation of the blockage ratio concurrently generates stronger turbulent secondary flow motions, which drastically alter the turbulent transport processes between the sidewall and duct center, giving rise to high-degrees of non-equilibrium states. The dynamics of coherent structures are studied by examining characteristics of the instantaneous velocity field, swirling strength, spatial two-point auto-correlations, and velocity spectra. The impact of the blockage ratio on the turbulent heat transfer is investigated in the second numerical study. The results show that owing to the existence of the ribs and confinement of the duct, organized secondary flows appear as large streamwise-elongated vortices, which have profound influences on the transport of momentum and thermal energy. This study also shows that the spatial distribution and magnitude of the drag and heat transfer coefficients are highly sensitive to the rib height. The final study focuses on a comparison of highly-disturbed turbulent flows in a square duct with inclined and V-shaped ribs mounted on one wall. The turbulence field is highly sensitive to not only the rib geometry but also the boundary layers developed over the side and top walls. Owing to the difference in the pattern of the cross-stream secondary flow motions of these two ribbed duct cases, the flow physics in the inclined rib case is significantly different from the V-shaped rib case. It is found that near the leeward and windward faces of the ribs, the mean inclination angle of turbulence structures in the V-shaped rib case is greater than that of the inclined rib case, which subsequently enhances momentum transport between the ribbed bottom wall and the smooth top wall.
Download or read book A 3 D Numerical Simulation of Fluid Flow Through a Porous Rectangular Duct written by Ravi Gudimetla and published by . This book was released on 1997 with total page 144 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Predicting Turbulent Convective Heat Transfer in Three Dimensional Duct Flows written by and published by . This book was released on 1999 with total page 26 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Direct Numerical Simulation of Turbulent Flow and Heat Transfer in a Square Duct at Low Reynolds Number written by M. Piller and published by . This book was released on 2001 with total page 8 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this paper, we present the results from Direct Numerical Simulations of turbulent, incompressible flow through a square duct, with an imposed temperature difference between two opposite walls, while the other two walls are assumed perfectly insulated. The mean flow is sustained by an imposed, mean pressure gradient. The most interesting feature, characterizing this geometry, consists in the presence of turbulence-sustained mean secondary motions in the cross-flow plane. In this study, we focus on weak turbulence, in that the Reynolds number, based on bulk velocity and hydraulic diameter, is about 4450. Our results indicate that secondary motions do not affect dramatically the global parameters, like friction factor and Nusselt number, in comparison with the plane-channel flow. This issue is investigated by looking at the distribution of the various contributions to the total heat flux, with particular attention to the mean convective term, which does not appear in the plane channel flow.
Download or read book A Finite difference Code for the Conjugated Forced Convection conduction Heat Transfer of Turbulent Flow in a Rectangular Duct written by James French Blodget and published by . This book was released on 1987 with total page 338 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Numerical Simulation of Separated and Secondary Flows in Diffusing S ducts for Air Breathing Propulsion written by Colin J. Fiola and published by . This book was released on 2013 with total page 70 pages. Available in PDF, EPUB and Kindle. Book excerpt: The focus of this thesis is on numerical simulation of incompressible and compressible flow in a diffusing S-duct inlet. S-ducts are very common components of both commercial and militaryaircraft, for example the Boeing 727 and McDonnell Douglas F-18. The F-18, being a relatively small aircraft, requires a short, highly curved S-duct with non-uniform cross-sectional area. The S-duct decelerates the flow, increasing the static pressure, in order to provide a uniform velocity and pressure distribution at the engine face. The curved nature and increasing cross sectional area creates secondary flows and boundary layer separation which causes non-uniform flow and total pressure loss at the engine face. Total pressure loss and flow non-uniformity at the engine face reduce engine performance and cause increased wear on parts such as turbine blades. Engine stall is also a concern when the flow inside the S-Duct becomes highly distorted. An ideal S-duct would efficiently decelerate flow uniformly while minimizing total pressure loss and magnitude of transverse velocity components. Due to the necessity to minimize size and maximize stealth of aircraft, including Unmanned Aerial Vehicles (UAVs) and cruise missiles, designers are challenged to use shorter and more highly curved S-Ducts. The accurate modeling of flow in S-duct is therefore a problem of great interest and significance in propulsion. In this thesis, we study the flow field in S-ducts by numerical simulations using the Reynolds-Averaged Navier-Stokes (RANS) equations in conjunction with a variety of one - and two equation turbulence models such as one-equation Spalart-Allmaras model, the two-equation k-[epsilon] and SST k-[omega] models, and the four equations Transition SST model. Two S-duct geometries are employed in this investigation - one is used in an experimental study conducted at NASA Glenn Research Center in the early 1990's, the other is a benchmark configuration proposed by AIAA Propulsion Aerodynamics Workshop to assess the accuracy and best practices of CFD solvers. The CFD flow solver ANSYS-FLUENT is employed for computing the incompressible/compressible flow inside the S-ducts. A structured mesh is generated using GAMBIT. A second-order accurate steady density-based solver is employed in a finite-volume framework. The computed results compare well with the experimental data and with the computations of other investigators. The flow field and pressure recovery are captured with good accuracy. The best practices for CFD modeling, namely the mesh density, the accuracy of the algorithm and the turbulence model, of S-duct flow field are identified.
Download or read book Heat Transfer and Friction Augmentation in a Narrow Rectangular Duct with Symmetrical and Non symmetrical Wedge shaped Turbulators written by Michelle Valentino and published by . This book was released on 2011 with total page 291 pages. Available in PDF, EPUB and Kindle. Book excerpt: The need for cleaner and more fuel efficient means to produce electricity is growing steadily. Advancements in cooling technologies contribute to the improvements in turbine efficiency and are used for gas turbines and for power generation in automotive, aviation, as well as in naval applications, and many more. Studies introducing turbulators on walls of internal cooling channels, which can be applied to hot gas components and in recuperative heat exchangers, have been reviewed for their ability to promote heat transfer in the channel while observing pressure loss caused by adding the features. Several types of turbulators have been studied; ribs, pin fins, dimples, wedges, and scales are some examples of features that have been added to walls of internal cooling channels or heat exchangers to increase heat transfer. This study focuses on two types of wedge turbulator designs, a full symmetrical wedge and a half, or non-symmetrical right-triangular wedge for the purpose of disrupting the thermal boundary layer close to hot walls without causing large-scale mixing and pressure drops. There are two sizes of the wedges, the first set of full and half wedges have an e/Dh=0.10 with the second at e/Dh=0.40, a feature that fills the height of the boundary layer. There are six cases studied, two one-wall and four two-wall cases in a 2:1 aspect ratio channel at Reynolds numbers of 10,000, 20,000, 30,000, and 40,000. Two experimental setups are utilized: a segmented copper block and transient TLC, along with numerical simulation for computational flow visualization. Wall temperature data is collected from all four walls for the copper experimental setup and three walls on the transient TLC setup. The fourth wall of the acrylic test section for the transient TLC tests is utilized for pressure testing, where static pressure ports are placed along the side wall. Although the small features did not show large influence in heat transfer on the side walls as much as the larger features or as high of heat transfer on the featured walls, the minimal pressure loss in the channel kept overall thermal performance of the small two wall full wedge features very high. The case of the large half wedge on two walls also showed very high thermal performance, having pressure loss values nearly half of the same sized (length and height) full wedge feature while having the ability to incorporate side walls into the overall heat transfer enhancement. The results found in the experimental setups are supported by the visualization of flow characteristics from the numerical testing. Comparing the initial wedge study to recent full rib studies show the wedges have similar improvements in heat transfer to the full rib cases with friction augmentations 5 to 10 times lower than the full rib cases. Further improvements to wedge heat transfer and pressure drop can be done by determining optimal wedge size and orientation.
Download or read book Numerical Simulation of Turbulent Heat Transfer and Flow in a Rotating Multiple pass Square Channel written by Jenn-Jiang Hwang and published by . This book was released on 1997 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Presented at the International Gas Turbine & Aeroengine Congress & Exhibition, Orlando, FL, Jun 2 - Jun 5, 1997.
Download or read book Numerical Simulation of the Air Flow Field in a Laboratory Fume Hood Using the CFD ACE TM Computational Fluid Dynamics Code written by Cedric Benedict D'Sousa and published by . This book was released on 1997 with total page 162 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Laminar Flow Forced Convection in Ducts written by R. K. Shah and published by Academic Press. This book was released on 2014-06-28 with total page 492 pages. Available in PDF, EPUB and Kindle. Book excerpt: Laminar Flow Forced Convection in Ducts is a sourcebook for compact heat exchanger analytical data. This book describes the analytical solutions for laminar fluid flow and forced convection heat transfer in circular and noncircular pipes, including applicable differential equations and boundary conditions involving velocity and temperature problems of fluid flow. The book also discusses fluid flow—how much power is required to pump fluids through the heat exchanger, as well as the heat transfer—the determination of q" distribution, and the temperature of fluid and walls. The text also analyzes the coolant or heat transfer fluid flows in a nuclear power reactor composed of a bundle of circular section fuel rods located inside a round tube. R.A. Axford addresses fluid flow and heat transfers results for the rod bundle geometry in "Heat Transfer in Rod Bundles." The book also provides an overview and guidelines that can be used for the designer and the applied mathematician. This book is suitable for engineers working in electronics, aerospace, instrumentation, and biomechanics that use cooling or heating exchanges or solar collection systems.
Download or read book Direct Numerical Simulation of Turbulent Flow and Heat Transfer in a Concentric Annular Pipe written by Edris Bagheri and published by . This book was released on 2021 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this thesis, the effects of computational domain size and radius ratio on fully developed turbulent flow and heat transfer in a concentric annular pipe are investigated using direct numerical simulation (DNS). To perform DNS, a new parallel computer code based on the pseudo-spectral method was developed using the FORTRAN 90/95 programing languages and the message passing interface (MPI) libraries. In order to study the effects of computational domain size on the turbulence statistics, twelve test cases of different domain sizes are compared. The effects of radius ratio are investigated through a systematic study based on four radius ratios of a concentric pipe. The characteristics of the velocity and temperature fields are examined at two Reynolds number of Re_(D_h ) =8900$ and 17700. The radius ratio affects the interaction of two boundary layers of the concentric annular pipe and has a significant impact on the turbulent flow structures and dynamics. The characteristics of the flow and temperature fields are investigated in both physical and spectral spaces, which include the analyses of the first- and second-order statistical moments, budget balance of the transport equation of Reynolds stresses, two-point correlation coefficients, and premultiplied spectra of velocity, vorticity, and temperature fluctuations. It is observed that the scales and dynamics of turbulence structures vary with the radius ratio as well as the surface curvature of the concave and convex walls. The characteristic length scales of the turbulence structures are identified through a spectral analysis.
Download or read book Numerical Simulation of Heat Transfer in Turbulent Pipe Flow with Structured Wall Surfaces written by Peter Renze and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
