Download or read book Large Eddy Simulation for Heat Transfer Prediction in a Gas Turbine Environment written by Sanjiva Keshava Lele and published by . This book was released on 2007 with total page 66 pages. Available in PDF, EPUB and Kindle. Book excerpt: A thorough investigation of leading edge heat transfer on a model geometry has been performed using Large-eddy simulation (LES). with support from the current and a previous AFOSR grant. The results from the leading edge study are presented as a detailed Appendix in this report. To address the problem of solving the full three-dimensional turbulent flow in a turbine passage. including the effects of free-stream turbulence from the combustor, and the unsteady interactions between various blade rows in the form of moving wakes and shocks it was necessary to extend the LES solver. A high-order overset LES code suitable for the study of turbomachinery passages has been developed. This approach is summarized in this report. Some preliminary results have been obtained using this code, mostly as cases for code validation. The code is currently being used to investigate flow in turbine passages under realistic conditions, and detailed comparisons with available experiments will be made.

Download or read book Large Eddy Simulation of High Pressure Turbine Cascade written by Rathakrishnan Bhaskaran and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: In gas turbine engine design, better efficiency is achieved through higher turbine inlet temperature. As a result, the nozzle guide vanes and rotor blades of a High Pressure Turbine (HPT) are subject to an increasingly hostile thermal environment. High levels of turbulence and hot streaks from the upstream combustor impinge on the HPT blade rows. Heat transfer prediction of the thermally critical regions of a HPT is a vital element in the design of gas turbine engines. The effect of inlet turbulence on heat transfer and boundary layer development on a HPT vane cascade has been studied numerically using a high-order overset Large Eddy Simulation procedure. Numerical visualizations of instantaneous boundary layer flow show presence of long, meandering, streamwise oriented streaky structures on both the suction and pressure sides of the blade. Stretching of vortices from the inlet turbulence around the leading edge and subsequent transport of them into the blade passage produces these boundary layer streaks. Significant enhancement in laminar heat transfer, especially around the leading edge and on the pressure side is observed due to these structures. Backward jets are created in the fluctuation velocity field in the boundary layer, which interact with eddies in the turbine passage leading to bypass transition of the suction surface boundary layer. Simulations with organized spanwise disturbance show sensitivity of leading edge region heat transfer to the intensity and length scale of the inlet disturbance.

Download or read book Direct and Large Eddy Simulation X written by Dimokratis G.E. Grigoriadis and published by Springer. This book was released on 2017-10-06 with total page 523 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book addresses nearly all aspects of the state of the art in LES & DNS of turbulent flows, ranging from flows in biological systems and the environment to external aerodynamics, domestic and centralized energy production, combustion, propulsion as well as applications of industrial interest. Following the advances in increased computational power and efficiency, several contributions are devoted to LES & DNS of challenging applications, mainly in the area of turbomachinery, including flame modeling, combustion processes and aeroacoustics. The book includes work presented at the tenth Workshop on 'Direct and Large-Eddy Simulation' (DLES-10), which was hosted in Cyprus by the University of Cyprus, from May 27 to 29, 2015. The goal of the workshop was to establish a state of the art in DNS, LES and related techniques for the computation and modeling of turbulent and transitional flows. The book is of interest to scientists and engineers, both in the early stages of their career and at a more senior level.

Download or read book A Large eddy Simulation Technique for the Prediction of Flow Mixing and Combustion in Gas Turbine Combustors written by Bernhard Wegner and published by . This book was released on 2007 with total page 117 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Direct and Large Eddy Simulation XI written by Maria Vittoria Salvetti and published by Springer. This book was released on 2019-02-02 with total page 608 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book gathers the proceedings of the 11th workshop on Direct and Large Eddy Simulation (DLES), which was held in Pisa, Italy in May 2017. The event focused on modern techniques for simulating turbulent flows based on the partial or full resolution of the instantaneous turbulent flow structures, as Direct Numerical Simulation (DNS), Large-Eddy Simulation (LES) or hybrid models based on a combination of LES and RANS approaches. In light of the growing capacities of modern computers, these approaches have been gaining more and more interest over the years and will undoubtedly be developed and applied further. The workshop offered a unique opportunity to establish a state-of-the-art of DNS, LES and related techniques for the computation and modeling of turbulent and transitional flows and to discuss about recent advances and applications. This volume contains most of the contributed papers, which were submitted and further reviewed for publication. They cover advances in computational techniques, SGS modeling, boundary conditions, post-processing and data analysis, and applications in several fields, namely multiphase and reactive flows, convection and heat transfer, compressible flows, aerodynamics of airfoils and wings, bluff-body and separated flows, internal flows and wall turbulence and other complex flows.

Download or read book Direct and Large Eddy Simulation IX written by Jochen Fröhlich and published by Springer. This book was released on 2015-01-27 with total page 656 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume reflects the state of the art of numerical simulation of transitional and turbulent flows and provides an active forum for discussion of recent developments in simulation techniques and understanding of flow physics. Following the tradition of earlier DLES workshops, these papers address numerous theoretical and physical aspects of transitional and turbulent flows. At an applied level it contributes to the solution of problems related to energy production, transportation, magneto-hydrodynamics and the environment. A special session is devoted to quality issues of LES. The ninth Workshop on 'Direct and Large-Eddy Simulation' (DLES-9) was held in Dresden, April 3-5, 2013, organized by the Institute of Fluid Mechanics at Technische Universität Dresden. This book is of interest to scientists and engineers, both at an early level in their career and at more senior levels.

Download or read book Flow and Combustion in Advanced Gas Turbine Combustors written by Johannes Janicka and published by Springer Science & Business Media. This book was released on 2012-10-29 with total page 495 pages. Available in PDF, EPUB and Kindle. Book excerpt: With regard to both the environmental sustainability and operating efficiency demands, modern combustion research has to face two main objectives, the optimization of combustion efficiency and the reduction of pollutants. This book reports on the combustion research activities carried out within the Collaborative Research Center (SFB) 568 “Flow and Combustion in Future Gas Turbine Combustion Chambers” funded by the German Research Foundation (DFG). This aimed at designing a completely integrated modeling and numerical simulation of the occurring very complex, coupled and interacting physico-chemical processes, such as turbulent heat and mass transport, single or multi-phase flows phenomena, chemical reactions/combustion and radiation, able to support the development of advanced gas turbine chamber concepts

Download or read book Large Eddy Simulations and Turbulence Modeling for Film Cooling written by Sumanta Acharya and published by . This book was released on 1999 with total page 140 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Reduced Order Models and Large Eddy Simulation for Combustion Instabilities in Aeronautical Gas Turbines written by Fabien Dupuy (docteur en physique).) and published by . This book was released on 2020 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Increasingly stringent regulations as well as environmental concerns have lead gas turbine powered engine manufacturers to develop the current generation of combustors, which feature lower than ever fuel consumption and pollutant emissions. However, modern combustor designs have been shown to be prone to combustion instabilities, where the coupling between acoustics of the combustor and the flame results in large pressure oscillations and vibrations within the combustion chamber. These instabilities can cause structural damages to the engine or even lead to its destruction. At the same time, considerable developments have been achieved in the numerical simulation domain, and Computational Fluid Dynamics (CFD) has proven capable of capturing unsteady flame dynamics and combustion instabilities for aforementioned engines. Still, even with the current large and fast increasing computing capabilities, time remains the key constraint for these high fidelity yet computationally intensive calculations. Typically, covering the entire range of operating conditions for an industrial engine is still out of reach. In that respect, low order models exist and can be efficient at predicting the occurrence of combustion instabilities, provided an adequate modeling of the flame/acoustics interaction as appearing in the system is available. This essential piece of information is usually recast as the so called Flame Transfer Function (FTF) relating heat release rate fluctuations to velocity fluctuations at a given point. One way to obtain this transfer function is to rely on analytical models, but few exist for turbulent swirling flames. Another way consists in performing costly experiments or numerical simulations, negating the requested fast prediction capabilities. This thesis therefore aims at providing fast, yet reliable methods to allow for low order combustion instabilities modeling. In that context, understanding the underlying mechanisms of swirling flame acoustic response is also targeted. To address this issue, a novel hybrid approach is first proposed based on a reduced set of high fidelity simulations that can be used to determine input parameters of an analytical model used to express the FTF of premixed swirling flames. The analytical model builds on previous works starting with a level-set description of the flame front dynamics while also accounting for the acoustic-vorticity conversion through a swirler. For such a model, validation is obtained using reacting stationary and pulsed numerical simulations of a laboratory scale premixed swirl stabilized flame. The model is also shown to be able to handle various perturbation amplitudes. At last, 3D high fidelity simulations of an industrial gas turbine powered by a swirled spray flame are performed to determine whether a combustion instability observed in experiments can be predicted using numerical analysis. To do so, a series of forced simulations is carried out in en effort to highlight the importance of the two-phase flow flame response evaluation. In that case, sensitivity to reference velocity perturbation probing positions as well as the amplitude and location of the acoustic perturbation source are investigated. The analytical FTF model derived in the context of a laboratory premixed swirled burner is furthermore gauged in this complex case. Results show that the unstable mode is predicted by the acoustic analysis, but that the flame model proposed needs further improvements to extend its applicability range and thus provide data relevant to actual aero-engines.

Download or read book Large Eddy Simulation LES of Turbulent Flows in Gas Turbine written by Maḥmūd Karīmī and published by . This book was released on 2007 with total page 282 pages. Available in PDF, EPUB and Kindle. Book excerpt: Compressible turbulent flow over a modern gas turbine blade is modeled in this thesis using Large Eddy Simulation (LES) methods. CFD simulation of turbo-machinery flows is a challenging problem due to the high Reynolds and Mach numbers of such flows. Reynolds Averages Navier Stokes (RANS) methods that are currently used in industry to model such turbulent flows do not give satisfactory results specifically at off-design conditions and therefore there is a need to further improve the turbulence modeling in the CFD simulations. Herein, different variations of the LES method are investigated to simulate this compressible turbulent flow. LES methodologies consist of Smagorinsky, Dynamic Smagorinsky, and Implicit LES accompanied by Yoshizawa and Van Driest relations. In this work, a 3D unstructured tetrahedral Navier-Stokes solver is applied using a mixed finite-volume-finite-element method. LES terms are discretized using the finite-element method. Parallel computation is performed according to MPI standards. LES pressure distribution results have significant differences with the 3D RANS results. Much more discrepancy is expected in velocity profiles, shear stresses, and heat transfer characteristics. Considering pressure distribution results and compared to the currently used RANS models, LES results are fairly superior especially in the off-design conditions. LES results of this work are more superior to RANS results in the regions close to leading edge which contains very high strain in fluid elements and it is not satisfactorily resolvable using RANS. RANS results of [66] are superior to LES results of this work for the mid suction side at which the turbulence structures are not resolved well in LES where a separation leads to constant pressure distribution which is captured as an attached flow in LES. This might be due to not introducing fluctuations at LES inlet and also to not having enough mesh resolution. Both LES and RANS results have difficulty resolving the shock/boundary layer interaction on the rear suction side of the blade. This might also be cured in LES by improving the mesh at that region or using adaptation methods or enhancing the shock capturing characteristics of the flux calculation method. The deficiencies of the LES simulation are discussed and possible cures and future works are elaborated. This work aims at accomplishing the first step and providing a solid basis for future works on an intellectually challenging topic which is of high importance in academia and industry: Turbulence Modeling.

Download or read book Large Eddy Simulation for Incompressible Flows written by P. Sagaut and published by Springer Science & Business Media. This book was released on 2006 with total page 600 pages. Available in PDF, EPUB and Kindle. Book excerpt: First concise textbook on Large-Eddy Simulation, a very important method in scientific computing and engineering From the foreword to the third edition written by Charles Meneveau: "... this meticulously assembled and significantly enlarged description of the many aspects of LES will be a most welcome addition to the bookshelves of scientists and engineers in fluid mechanics, LES practitioners, and students of turbulence in general."

Download or read book Direct and Large Eddy Simulation XIII written by Cristian Marchioli and published by Springer Nature. This book was released on 2023-11-15 with total page 389 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book covers the diverse and cutting-edge research presented at the 13th ERCOFTAC Workshop on Direct and Large Eddy Simulation. The first section of the book focuses on Aerodynamics/Aeroacoustics, comprising eight papers that delve into the intricate relationship between fluid flow and aerodynamic performance. The second section explores the dynamics of Bluff/Moving Bodies through four insightful papers. Bubbly Flows, the subject of the third section, is examined through four papers. Moving on, the fourth section is dedicated to Combustion and Reactive Flows, presenting two papers that focus on the complex dynamics of combustion processes and the interactions between fluids and reactive species. Convection and Heat/Mass Transfer are the central themes of the fifth section, which includes three papers. These contributions explore the fundamental aspects of heat and mass transfer in fluid flows, addressing topics such as convective heat transfer, natural convection, and mass transport phenomena. The sixth section covers Data Assimilation and Uncertainty Quantification, featuring two papers that highlight the importance of incorporating data into fluid dynamic models and quantifying uncertainties associated with these models. The subsequent sections encompass a wide range of topics, including Environmental and Industrial Applications, Flow Separation, LES Fundamentals and Modelling, Multiphase Flows, and Numerics and Methodology. These sections collectively present a total of 23 papers that explore different facets of fluid dynamics, contributing to the advancement of the field and its practical applications.

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 Low Reynolds Number Heat Transfer Prediction Employing Large Eddy Simulation for Electronics Geometrics written by James C. Tyacke and published by . This book was released on 2009 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Application of Large Eddy Simulation to Cooling and Flow Problems in Aeropropulsion Systems written by Richard H. Pletcher and published by . This book was released on 2004 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The primary objective of this research was to develop and apply large eddy simulation (LES) technology to some urgent flow and heat transfer problems in propulsion systems and to contribute to the physical understanding of such flows. The work was motivated by the observation that the design goals of high specific power and thrust and low specific fuel consumption have been reached, in part, by an increase in turbine inlet temperature and future improvements in engine efficiency will place even greater demands on blade cooling procedures. However, current design codes are somewhat limited in accuracy due to uncertainty associated with modeling for turbulent flow. The research was concerned with both the film cooling of external blade surfaces and the complex flows in internal cooling passages. Studies have been completed of the effects of rotation on the heat transfer and flow in smooth and ribbed channels and in a duct of square cross-section. A scheme was developed for including the effects of freestream turbulence on boundary layer development. Preliminary LES results have been obtained for a single hole film cooling configuration.

Download or read book Application of Large Eddy Simulation to Cooling and Flow Problems in Aeropropulsion Systems written by and published by . This book was released on 2004 with total page 105 pages. Available in PDF, EPUB and Kindle. Book excerpt: The primary objective of this research was to develop and apply large eddy simulation (LES) technology to some urgent flow and heat transfer problems in propulsion systems and to contribute to the physical understanding of such flows. The work was motivated by the observation that the design goals of high specific power and thrust and low specific fuel consumption have been reached, in part, by an increase in turbine inlet temperature and future improvements in engine efficiency will place even greater demands on blade cooling procedures. However, current design codes are somewhat limited in accuracy due to uncertainty associated with modeling for turbulent flow. The research was concerned with both the film cooling of external blade surfaces and the complex flows in internal cooling passages. Studies have been completed of the effects of rotation on the heat transfer and flow in smooth and ribbed channels and in a duct of square cross-section. A scheme was developed for including the effects of freestream turbulence on boundary layer development. Preliminary LES results have been obtained for a single hole film cooling configuration.

Download or read book Radiation Heat Transfer Modelling with Computational Fluid Dynamics written by Yehuda Sinai and published by CRC Press. This book was released on 2022-06-21 with total page 215 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book serves as a preliminary reference for the principles of thermal radiation and its modelling in computational fluid dynamics (CFD) simulations. Radiation Heat Transfer Modelling with Computational Fluid Dynamics covers strategies and processes for synthesizing radiation with CFD setups, computational techniques for solving the radiative transfer equation, the strengths and weaknesses thereof, boundary and initial conditions and relevant guidelines. Describing the strategic planning of a typical project, the book includes the spectroscopic properties of gases, some particulates and porous media. FEATURES Fills a gap between existing CFD and thermal radiation textbooks and elaborates on some aspects of user manuals. Aims at (1) CFD practitioners who are newcomers to thermal radiation and are looking for a preliminary introduction thereon and (2) modellers familiar with thermal radiation looking for a precursory introduction to CFD. The book is tilted somewhat towards the first group. Provides guidelines for choosing the right model, the strategic planning of the modelling and its implementation. Outlines the pitfalls of some solution techniques. Describes how radiation is included in the variety of boundary condition types offered by CFD codes. Helps to develop the practical skills required to plan, implement and interpret thermal radiation within the typical CFD code. Addresses a wide variety of physical circumstances in which thermal radiation plays a role. Offers ample references for readers searching for additional details. Includes several examples of practical applications, including fire, a utility boiler and car headlights in cold environments. This book is intended for researchers and professionals who wish to simulate problems that involve fluid flow and heat transfer with thermal radiation.