The Effects of Blade Count on Boundary Layer Development in a Low-Pressure Turbine PDF Download
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Author: Daniel J. Dorney
Publisher:
ISBN:
Category :
Languages : en
Pages : 24
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Book Description
Author: Daniel J. Dorney
Publisher:
ISBN:
Category :
Languages : en
Pages : 24
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Book Description
Author: National Aeronautics and Space Administration (NASA)
Publisher: Createspace Independent Publishing Platform
ISBN: 9781721008315
Category :
Languages : en
Pages : 28
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Book Description
Experimental data from jet-engine tests have indicated that unsteady blade row interactions and separation can have a significant impact on the efficiency of low-pressure turbine stages. Measured turbine efficiencies at takeoff can be as much as two points higher than those at cruise conditions. Several recent studies have revealed that Reynolds number effects may contribute to the lower efficiencies at cruise conditions. In the current study numerical simulations have been performed to study the boundary layer development in a two-stage low-pressure turbine, and to evaluate the transition models available for low Reynolds number flows in turbomachinery. The results of the simulations have been compared with experimental data, including airfoil loadings and integral boundary layer quantities. The predicted unsteady results display similar trends to the experimental data, but significantly overestimate the amplitude of the unsteadiness. The time-averaged results show close agreement with the experimental data.Dorney, Daniel J. and Ashpis, David E. and Halstead, David E. and Wisler, David C.Glenn Research CenterJET ENGINES; TWO STAGE TURBINES; COMPUTERIZED SIMULATION; BALDWIN-LOMAX TURBULENCE MODEL; BOUNDARY LAYER TRANSITION; TRANSITION FLOW; FLOW VISUALIZATION; BOUNDARY LAYER SEPARATION; SEPARATED FLOW; ROTOR BLADES (TURBOMACHINERY); TAKEOFF; CRUISING FLIGHT; COMPUTATIONAL GRIDS; NOZZLE FLOW; SKIN FRICTION; TURBINE BLADES; REYNOLDS NUMBER; FLOW CHARACTERISTICS; FLOW DISTRIBUTION
Author: Daniel J. Dorney
Publisher:
ISBN:
Category :
Languages : en
Pages : 30
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Book Description
Author: Burak Ozturk
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
Detailed experimental investigation has been conducted to provide a detailed insight into the heat transfer and aerodynamic behavior of a separation zone that is generated as a result of boundary layer development along the suction surface of a highly loaded low pressure turbine (LPT) blade. The research experimentally investigates the individual and combined effects of periodic unsteady wake flows and freestream turbulence intensity (Tu) on heat transfer and aerodynamic behavior of the separation zone. Heat transfer experiments were carried out at Reynolds number of 110,000, 150,000, and 250,00 based on the suction surface length and the cascade exit velocity. Aerodynamic experiments were performed at Re = 110,000 and 150,000. For the above Re-numbers, the experimental matrix includes Tus of 1.9%, 3.0%, 8.0%,13.0% and three different unsteady wake frequencies with the steady inlet flow as the reference configuration. Detailed heat transfer and boundary layer measurements are performed with particular attention paid to the heat transfer and aerodynamic behavior of the separation zone at different Tus at steady and periodic unsteady flow conditions. The objectives of the research are (a) to quantify the effect of Tu on the aero-thermal behavior of the separation bubble at steady inlet flow condition, (b) to investigate the combined effects of Tu and the unsteady wake flow on the aero-thermal behavior of the separation bubble, and (c) to provide a complete set of heat transfer and aerodynamic data for numerical simulation that incorporates Navier-Stokes and energy equations. The analysis of the experimental data reveals details of boundary layer separation dynamics which is essential for understanding the physics of the separation phenomenon under periodic unsteady wake flow and different Reynolds number and Tu. To provide a complete picture of the transition process and separation dynamics, extensive intermittency analysis was conducted. Ensemble averaged maximum and minimum intermittency functions were determined leading to the relative intermittency function. In addition, the detailed intermittency analysis reveals that the relative intermittency factor follows a Gaussian distribution confirming the universal character of the relative intermittency function.
Author: Ki-Hyeon Sohn
Publisher:
ISBN:
Category : Boundary layers
Languages : en
Pages : 16
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Book Description
Author: Daniel J. Dorney
Publisher:
ISBN:
Category : Turbine pumps
Languages : en
Pages : 26
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Book Description
Author: Cavour H. Hauser
Publisher:
ISBN:
Category : Aircraft gas-turbines
Languages : en
Pages : 30
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Book Description
Author: John P. Casey
Publisher:
ISBN: 9781423517092
Category :
Languages : en
Pages : 201
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Book Description
Three dimple patterns were investigated to ascertain their relative effectiveness on controlling boundary layer separation from a low-pressure turbine blade. The three cases included a single row of dimples at 65% of the axial chord with 2.22 cm spacing, a single row of dimples at 65% of the axial chord with 4.44 cm spacing, and a two-row staggered pattern with rows at 65% and 76% of the axial chord with 4.44 cm spacing. The multiple row case was such that the center of the upstream dimple set at the midpoint between two downstream dimples. The dimple spacing was measured center-on-center. Each of the dimple patterns was studied and compared to an unmodified blade at axial chord Reynolds numbers based on inlet velocity of 25k, 45k, and 100k. Experimental data was collected in a low-speed, draw down wind tunnel containing a linear turbine cascade of 8 Pak-B blades. Measurements of surface pressure, boundary layer parameters, wake velocity, and total pressure losses were made to examine the flow. No dimple pattern dramatically outperformed the others. Each of the dimple patterns studied improved the average total pressure loss coefficient by 34% for Re 25k and 1% Tu. Complementing the experimental effort was a three-dimensional computational fluid dynamics study. Four models were built and analyzed. The models included an unmodified blade, blades with dimples at 65% of the axial chord with 2 cm or 4 cm spacing, respectively, and a multiple row case consisting of dimples at 65% and 76% of the axial chord with 2 cm spacing. Again the upstream dimple set at the midpoint between two downstream dimples. The computational fluid dynamics study provided detailed flow visualization in and around the dimples as well as a comparison to experimental data for solver verification. It was shown that the computational and experimental results showed similar trends in wake loss and boundary layer traverses.
Author: John P. Casey
Publisher:
ISBN:
Category : Laminar boundary layer
Languages : en
Pages : 356
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Book Description
Author: Zhengping Zou
Publisher: Springer
ISBN: 9811057508
Category : Technology & Engineering
Languages : en
Pages : 572
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Book Description
This book is a monograph on aerodynamics of aero-engine gas turbines focusing on the new progresses on flow mechanism and design methods in the recent 20 years. Starting with basic principles in aerodynamics and thermodynamics, this book systematically expounds the recent research on mechanisms of flows in axial gas turbines, including high pressure and low pressure turbines, inter-turbine ducts and turbine rear frame ducts, and introduces the classical and innovative numerical evaluation methods in different dimensions. This book also summarizes the latest research achievements in the field of gas turbine aerodynamic design and flow control, and the multidisciplinary conjugate problems involved with gas turbines. This book should be helpful for scientific and technical staffs, college teachers, graduate students, and senior college students, who are involved in research and design of gas turbines.
