Download or read book Heat Transfer Characteristics of Turbulent Flow in a Square Channel with Angled Discrete Ribs written by S. C. Lau and published by . This book was released on 1990 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Experiments have been conducted to study the turbulent heat transfer and friction for fully developed flow of air in a square channel in which two opposite walls are roughened with 90 deg full ribs, parallel and crossed full ribs with angles of attack (Alpha) of 60 and 45 deg, 90 deg discrete ribs, and parallel and crossed discrete ribs with Alpha = 60, 45, and 30 deg. The discrete ribs are staggered in alternate rows of three and two ribs. Results are obtained for a rib height-to-channel hydraulic diameter ratio of 0.0625, a rib pitch-to-height ratio of 10, and Reynolds numbers between 10,000 and 80,000. Parallel angled discrete ribs are superior to 90 deg discrete ribs and parallel angled full ribs, and are recommended for internal cooling passages in gas turbine airfoils. For Alpha = 60 and 45 deg, parallel discrete ribs have higher ribbed wall heat transfer, lower smooth wall heat transfer, and lower channel pressure drop than parallel full ribs. Parallel 60 deg discrete ribs have the highest ribbed wall heat transfer and parallel 30 deg discrete ribs cause the lowest pressure drop. The heat transfer and pressure drops in crossed angled full and discrete rib cases are all lower than those in the corresponding 90 deg and parallel angled rib cases. Crossed arrays of angled ribs have poor thermal performance and are not recommended.
Download or read book Detailed Understanding of Flow Heat Transfer and Pressure Drop Behavior in a Square Channel with 45 Deg Ribs written by Lumaya Ahmed and published by . This book was released on 2018 with total page 183 pages. Available in PDF, EPUB and Kindle. Book excerpt: Internal Duct Cooling (IDC) with rib turbulators is one of the common cooling techniques applied inside the turbine airfoils. It is very important for the gas turbine industry to design and develop an optimized cooling channel that maximizes the amount of heat removed, while simultaneously minimizing the pressure drop for a target overall cooling effectiveness. Angled ribs perform superior to the transverse ribs due to additional secondary flow associated with them. However, they result in a highly non-homogenous heat transfer distribution, which is a manifestation of the complex, turbulent flow field inside the channel. It is very important to comprehend the secondary flow physics to characterize the heat transfer distribution in such angled ribbed channels. Additionally, due to the manufacturing constraint, the gas turbine industry encounters a challenge to make ribs edge sharp and results in ribs with rounded edges. The one of the main objectives of the present study is to provide a fundamental understanding of the flow physics on the heat transfer and pressure drop behavior in 45° ribbed channels both with sharp and rounded-edge ribs. It is found that the secondary flow has a significant effect on the heat transfer behavior for both types of ribs. There is a great need of high-fidelity PIV flow field data in the inter-rib space for an angled ribbed channel which can be used for CFD validation, especially for LES. The current study provides benchmarking flow field data in the inter-rib space in a square channel with 45° ribs using stereoscopic PIV technique. Besides the experiments, numerical studies were also conducted by using LES and different RANS models. The LES results show an excellent prediction capability for aerothermal behavior in such channels. However, the prediction capability of RANS models is found to be inconsistent for different rib configurations and flow conditions.
Download or read book Heat Transfer in Gas Turbines written by Bengt Sundén and published by Witpress. This book was released on 2001 with total page 544 pages. Available in PDF, EPUB and Kindle. Book excerpt: This title presents and reflects current active research on various heat transfer topics and related phenomena in gas turbine systems. It begins with a general introduction to gas turbine heat transfer, before moving on to specific areas.
Download or read book Turbulent Heat Transfer and Friction in a Square Channel with Discrete Rib Turbulators written by Robert Dale McMillin and published by . This book was released on 1989 with total page 236 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book ASME Technical Papers written by and published by . This book was released on 2001 with total page 488 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Journal of Turbomachinery written by and published by . This book was released on 1994 with total page 800 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 Paper written by and published by . This book was released on 2001 with total page 506 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Introduction to Heat Transfer written by Bengt Sundén and published by WIT Press. This book was released on 2012 with total page 365 pages. Available in PDF, EPUB and Kindle. Book excerpt: Presenting the basic mechanisms for transfer of heat, this book gives a deeper and more comprehensive view than existing titles on the subject. Derivation and presentation of analytical and empirical methods are provided for calculation of heat transfer rates and temperature fields as well as pressure drop. The book covers thermal conduction, forced and natural laminar and turbulent convective heat transfer, thermal radiation including participating media, condensation, evaporation and heat exchangers. This book is aimed to be used in both undergraduate and graduate courses in heat transfer and thermal engineering. It can successfully be used in R & D work and thermal engineering design in industry and by consultancy firms
Download or read book NASA SP written by and published by . This book was released on 1992 with total page 654 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Experimental and Numerical Investigation of Turbulent Flow and Heat mass Transfer in a Two pass Trapezoidal Channel with Turbulence Promoters written by Sung Hyuk Oh and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Experiments and numerical predictions were conducted to study heat (mass) transfer characteristics in a two-pass trapezoidal channel simulating the cooling passage of a gas turbine blade. Three different rib configurations were tested for the air entering the smaller cross section of the trapezoidal channel as well as the larger cross section of the trapezoidal channel at four different Reynolds numbers of 9,400, 16,800, 31,800, and 57,200. (+) 60[degree] ribs, ( -- ) 60[degree] ribs and 60[degree] V-shaped ribs were attached on both the top and bottom walls in parallel sequence. A naphthalene sublimation technique was used, and the heat and mass transfer analogy was applied to convert the mass transfer coefficients to heat transfer coefficients. Numerical predictions of three-dimensional flow and heat transfer also were performed for the trapezoidal channel with and without 90[degree] ribs tested by Lee et al. (2007). Reynolds stress turbulence model (RSM) in the FLUENT CFD code was used to calculate the heat transfer coefficients and flow fields at Re = 31,800. The results showed that the combined effects of the rib angle, rib orientation, and the sharp 180[degree] turn significantly affected the heat (mass) transfer distributions. The secondary flows induced by the sharp 180[degree] turn and the angled or V-shaped ribs played a very prominent role in heat (mass) transfer enhancements. The heat (mass) transfer enhancements and the pressure drops across the turn for 60[degree] V-shaped ribs had the highest values, then came the case of (+) 60[degree] ribs, and the heat (mass) transfer enhancements and the friction factor ratios for ( -- ) 60[degree] ribs was the lowest. However, comparing ( -- ) 60[degree] ribs with the 90[degree] ribs, ( -- ) 60[degree] ribs produced higher heat (mass) transfer enhancements than the 90[degree] ribs, as results of the secondary flow induced by the ( -- ) 60[degree] ribs. The overall average heat (mass) transfer for the larger inlet cases was always higher than that for the smaller inlet cases in the ribbed trapezoidal channel. Considering the thermal performance comparisons of the (+) 60[degree] ribs, the ( -- ) 60[degree] ribs, and 60[degree] V-shaped ribs for the smaller inlet cases, the highest thermal performance was produced by the ( -- ) 60[degree] ribs, and the 60[degree] V-shaped ribs and the (+) 60[degree] ribs had almost the same levels of the thermal performance since the 60[degree] V-shaped ribs produced the highest heat (mass) transfer enhancement but also produced highest pressure drops. For the larger inlet cases, the (+) 60[degree] ribs produced the highest values, then came the case of the 60[degree] V-shaped ribs, and the thermal performance for the ( -- ) 60[degree] ribs was the lowest. The Reynolds stress model (RSM) showed well flow fields and heat transfer distributions but underpredicted average Nusselt number ratios.
Download or read book Introduction to Enhanced Heat Transfer written by Sujoy Kumar Saha and published by Springer. This book was released on 2019-06-29 with total page 103 pages. Available in PDF, EPUB and Kindle. Book excerpt: This Brief stands as a primer for heat transfer fundamentals in heat transfer enhancement devices, the definition of heat transfer area, passive and active enhancement techniques and their potential and benefits and commercial applications. It further examines techniques and modes of heat transfer like single-phase flow and two-phase flow, natural and forced convection, radiation heat transfer and convective mass transfer.
Download or read book Proceedings of the ASME JSME Thermal Engineering Joint Conference Electrohydrodynamic heat transfer augmentation written by and published by . This book was released on 1991 with total page 554 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book General Papers in Heat and Mass Transfer Insulation and Turbomachinery written by Shih Hung Chan and published by . This book was released on 1994 with total page 226 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book 30th AIAA Thermophysics Conference written by and published by . This book was released on 1995 with total page 612 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Journal of Thermophysics and Heat Transfer written by and published by . This book was released on 2006 with total page 996 pages. Available in PDF, EPUB and Kindle. Book excerpt: This journal is devoted to the advancement of the science and technology of thermophysics and heat transfer through the dissemination of original research papers disclosing new technical knowledge and exploratory developments and applications based on new knowledge. It publishes papers that deal with the properties and mechanisms involved in thermal energy transfer and storage in gases, liquids, and solids or combinations thereof. These studies include conductive, convective, and radiative modes alone or in combination and the effects of the environment.
Download or read book Gas Turbine Heat Transfer and Cooling Technology Second Edition written by Je-Chin Han and published by CRC Press. This book was released on 2012-11-27 with total page 892 pages. Available in PDF, EPUB and Kindle. Book excerpt: A comprehensive reference for engineers and researchers, Gas Turbine Heat Transfer and Cooling Technology, Second Edition has been completely revised and updated to reflect advances in the field made during the past ten years. The second edition retains the format that made the first edition so popular and adds new information mainly based on selected published papers in the open literature. See What’s New in the Second Edition: State-of-the-art cooling technologies such as advanced turbine blade film cooling and internal cooling Modern experimental methods for gas turbine heat transfer and cooling research Advanced computational models for gas turbine heat transfer and cooling performance predictions Suggestions for future research in this critical technology The book discusses the need for turbine cooling, gas turbine heat-transfer problems, and cooling methodology and covers turbine rotor and stator heat-transfer issues, including endwall and blade tip regions under engine conditions, as well as under simulated engine conditions. It then examines turbine rotor and stator blade film cooling and discusses the unsteady high free-stream turbulence effect on simulated cascade airfoils. From here, the book explores impingement cooling, rib-turbulent cooling, pin-fin cooling, and compound and new cooling techniques. It also highlights the effect of rotation on rotor coolant passage heat transfer. Coverage of experimental methods includes heat-transfer and mass-transfer techniques, liquid crystal thermography, optical techniques, as well as flow and thermal measurement techniques. The book concludes with discussions of governing equations and turbulence models and their applications for predicting turbine blade heat transfer and film cooling, and turbine blade internal cooling.
