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  • 1
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    Transonic turbine blade loading calculations using different turbulence models – effects of reflecting and non-reflecting boundary conditions (2007)
    Elsevier
    Details
    Publication Date: 2007-03-01
    Print ISSN: 1359-4311
    Electronic ISSN: 1873-5606
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Published by Elsevier
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    PAPER CURRENT
  • 2
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    Turbine Blade and Endwall Heat Transfer Measured in NASA Glenn's Transonic Turbine Blade Cascade (2000)
    In:  CASI
    Details
    Publication Date: 2018-06-05
    Description: Higher operating temperatures increase the efficiency of aircraft gas turbine engines, but can also degrade internal components. High-pressure turbine blades just downstream of the combustor are particularly susceptible to overheating. Computational fluid dynamics (CFD) computer programs can predict the flow around the blades so that potential hot spots can be identified and appropriate cooling schemes can be designed. Various blade and cooling schemes can be examined computationally before any hardware is built, thus saving time and effort. Often though, the accuracy of these programs has been found to be inadequate for predicting heat transfer. Code and model developers need highly detailed aerodynamic and heat transfer data to validate and improve their analyses. The Transonic Turbine Blade Cascade was built at the NASA Glenn Research Center at Lewis Field to help satisfy the need for this type of data.
    Keywords: Aircraft Propulsion and Power
    Type: Research and Technology 1999; NASA/TM-2000-209639
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 3
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    Effects of Freestream Turbulence on Turbine Blade Heat Transfer (2004)
    In:  Other Sources
    Details
    Publication Date: 2019-07-18
    Description: Experiments have shown that moderate turbulence levels can nearly double turbine blade stagnation region heat transfer. Data have also shown that heat transfer is strongly affected by the scale of turbulence as well as its level. In addition to the stagnation region, turbulence is often seen to increase pressure surface heat transfer. This is especially evident at low to moderate Reynolds numbers. Vane and rotor stagnation region, and vane pressure surface heat transfer augmentation is often seen in a pre-transition environment. Accurate predictions of transition and relaminarization are critical to accurately predicting blade surface heat transfer. An approach is described which incorporates the effects of both turbulence level and scale into a CFD analysis. The model is derived from experimental data for cylindrical and elliptical leadng edges. Results using this model are compared to experimental data for both vane and rotor geometries. The comparisons are made to illustrate that using a model which includes the effects of turbulence length scale improves agreement with data, and to illustrate where improvements in the modeling are needed.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: Minnowbrook IV: 2003 Workshop on Transition and Unsteady Aspects of Turbomachinery Flows; 36; NASA/TM-2004-212913
    Format: text
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    NASA TECHNICAL REPORTS
  • 4
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    Simulation of VSPT Experimental Cascade Under High and Low Free-Stream Turbulence Conditions (2015)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Variable-Speed Power Turbines (VSPT) for rotorcraft applications operate at low Reynolds number and over a wide range in incidence associated with shaft speed change. A comprehensive linear cascade data set obtained includes the effects of Reynolds number, free-stream turbulence and incidence is available and this paper concerns itself with the presentation and numerical simulation of conditions resulting in a selected set of those data. As such, post-dictions of blade pressure loading, total-pressure loss and exit flow angles under conditions of high and low turbulence intensity for a single Reynolds number are presented. Analyses are performed with the three-equation turbulence models of Walters- Leylek and Walters and Cokljat. Transition, loading, total-pressure loss and exit angle variations are presented and comparisons are made with experimental data as available. It is concluded that at the low freestream turbulence conditions the Walters-Cokljat model is better suited to predictions while for high freestream conditions the two models generate similar predications that are generally satisfactory.
    Keywords: Fluid Mechanics and Thermodynamics; Aircraft Propulsion and Power
    Type: NASA/TM-2015-218457 , E-19014 , GRC-E-DAA-TN17470 , AIAA/ASME/SAE/ASEE Joint Propulsion Conference; Jul 28, 2014 - Jul 30, 2014; Cleveland, OH; United States
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 5
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    Complementary Aerodynamic Performance Datasets for Variable Speed Power Turbine Blade Section from Two Independent Transonic Turbine Cascades (2015)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Two independent experimental studies were conducted in linear cascades on a scaled, two-dimensional mid-span section of a representative Variable Speed Power Turbine (VSPT) blade. The purpose of these studies was to assess the aerodynamic performance of the VSPT blade over large Reynolds number and incidence angle ranges. The influence of inlet turbulence intensity was also investigated. The tests were carried out in the NASA Glenn Research Center Transonic Turbine Blade Cascade Facility and at the University of North Dakota (UND) High Speed Compressible Flow Wind Tunnel Facility. A large database was developed by acquiring total pressure and exit angle surveys and blade loading data for ten incidence angles ranging from +15.8deg to 51.0deg. Data were acquired over six flow conditions with exit isentropic Reynolds number ranging from 0.05106 to 2.12106 and at exit Mach numbers of 0.72 (design) and 0.35. Flow conditions were examined within the respective facility constraints. The survey data were integrated to determine average exit total-pressure and flow angle. UND also acquired blade surface heat transfer data at two flow conditions across the entire incidence angle range aimed at quantifying transitional flow behavior on the blade. Comparisons of the aerodynamic datasets were made for three "match point" conditions. The blade loading data at the match point conditions show good agreement between the facilities. This report shows comparisons of other data and highlights the unique contributions of the two facilities. The datasets are being used to advance understanding of the aerodynamic challenges associated with maintaining efficient power turbine operation over a wide shaft-speed range.
    Keywords: Aerodynamics
    Type: GRC-E-DAA-TN27685 , ISABE Conference; Oct 25, 2015 - Oct 30, 2015; Phoenix, AZ; United States
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 6
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    Validation of a CFD Methodology for Variable Speed Power Turbine Relevant Conditions (2013)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Analysis tools are needed to investigate aerodynamic performance of Variable-Speed Power Turbines (VSPT) for rotorcraft applications. The VSPT operates at low Reynolds numbers (transitional flow) and over a wide range of incidence. Previously, the capability of a published three-equation turbulence model to predict accurately the transition location for three-dimensional heat transfer problems was assessed. In this paper, the results of a post-diction exercise using a three-dimensional flow in a transonic linear cascade comprising VSPT blading are presented. The measured blade pressure distributions and exit total pressure and flow angles for two incidence angles corresponding to cruise (i = 5.8deg) and takeoff (i = -36.7deg) were used for this study. For the higher loading condition of cruise and the negative incidence condition of takeoff, overall agreement with data may be considered satisfactory but areas of needed improvement are also indicated.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: NASA/TM-2013-217860 , E-18653 , GT2013-95030 , ASME International Gas Turbine Institute (IGTI) Turbo Expo 2013; Jun 03, 2013 - Jun 07, 2013; San Antonio, TX; United States
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    NASA TECHNICAL REPORTS
  • 7
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    Aerodynamic Measurements of an Incidence Tolerant Blade in a Transonic Turbine Cascade (2012)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: An overview of the recent facility modifications to NASA s Transonic Turbine Blade Cascade Facility and aerodynamic measurements on the VSPT incidence-tolerant blade are presented. This work supports the development of variable-speed power turbine (VSPT) speed-change technology for the NASA Large Civil Tilt Rotor (LCTR) vehicle. In order to maintain acceptable main rotor propulsive efficiency, the VSPT operates over a nearly 50% speed range from takeoff to altitude cruise. This results in 50 or more variations in VSPT blade incidence angles. The Transonic Turbine Blade Cascade Facility has the ability to operate over a wide range of Reynolds numbers and Mach numbers, but had to be modified in order to accommodate the negative incidence angle variation required by the LCTR VSPT operation. Details of the modifications are described. An incidence-tolerant blade was developed under an RTPAS study contract and tested in the cascade to look at the effects of large incidence angle and Reynolds number variations. Recent test results are presented which include midspan exit total pressure and flow angle measurements obtained at three inlet angles representing the cruise, take-off, and maximum incidence flight mission points. For each inlet angle, data were obtained at five flow conditions with exit Reynolds numbers varying from 2.12 106 to 2.12 105 and two isentropic exit Mach numbers of 0.72 and 0.35. Three-dimensional flowfield measurements were also acquired at the cruise and take-off points. The flowfield measurements were acquired using a five-hole and three-hole pneumatic probe located in a survey plane 8.6% axial chord downstream of the blade trailing edge plane and covering three blade passages. Blade and endwall static pressure distributions were also acquired for each flow condition.
    Keywords: Aerodynamics
    Type: E-18470 , 2012 Fundamental Aeronautics Programs (FAP) Technical Conference; Mar 13, 2012 - Mar 15, 2012; Cleveland, OH; United States
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    NASA TECHNICAL REPORTS
  • 8
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    Aerodynamic Investigation of Incidence Angle Effects in a Large Scale Transonic Turbine Cascade (2013)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Aerodynamic measurements showing the effects of large incidence angle variations on an HPT turbine blade set are presented. Measurements were made in NASA's Transonic Turbine Blade Cascade Facility which has been used in previous studies to acquire detailed aerodynamic and heat transfer measurements for CFD code validation. The current study supports the development of variable-speed power turbine (VSPT) speed-change technology for the NASA Large Civil Tilt Rotor (LCTR) vehicle. In order to maintain acceptable main rotor propulsive efficiency, the VSPT operates over a nearly 50 percent speed range from takeoff to altitude cruise. This results in 50deg or more variations in VSPT blade incidence angles. The cascade facility has the ability to operate over a wide range of Reynolds numbers and Mach numbers, but had to be modified in order to accommodate the negative incidence angle variation required by the LCTR VSPT operation. Using existing blade geometry with previously acquired aerodynamic data, the tunnel was re-baselined and the new incidence angle range was exercised. Midspan exit total pressure and flow angle measurements were obtained at seven inlet flow angles. For each inlet angle, data were obtained at five flow conditions with inlet Reynolds numbers varying from 6.8310(exp 5) to 0.8510(exp 5) and two isentropic exit Mach numbers of 0.74 and 0.34. The midspan flowfield measurements were acquired using a three-hole pneumatic probe located in a survey plane 8.6 percent axial chord downstream of the blade trailing edge plane and covering three blade passages. Blade and endwall static pressure distributions were also acquired for each flow condition.
    Keywords: Aerodynamics
    Type: NASA/TM-2013-218070 , E-18746 , AIAA Paper 2012-3879 , Joint Propulsion Conference and Exhibit; Jul 29, 2012 - Aug 01, 2012; Atlanta, GA; United States
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 9
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    Heat Transfer Measurements on the Endwall of a Variable Speed Power Turbine Blade Cascade (2018)
    In:  CASI
    Details
    Publication Date: 2019-07-20
    Description: Heat transfer measurements were obtained on the endwall and a 2-D section of a variable speed power turbine (VSPT) rotor blade. Infrared thermography was used to help determine the transition of flow from laminar to turbulent as well asdetermine regions of flow separation. Steady state data was obtained for six incidence angles ranging from +50 degree to-17 degree, and at five flow conditions for each angle.
    Keywords: Aerodynamics
    Type: NASA/TM-2018-220033 , E-19632 , GRC-E-DAA-TN60642 , AHS International Annual Forum & Technology Display; May 14, 2018 - May 17, 2018; Phoenix, AZ; United States
    Format: application/pdf
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  • 10
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    Variable-Speed Power-Turbine Research at Glenn Research Center (2012)
    In:  CASI
    Details
    Publication Date: 2019-07-12
    Description: The main rotors of the NASA Large Civil Tilt-Rotor (LCTR) notional vehicle operate over a wide speed-range, from 100 percent at takeoff to 54 percent at cruise. The variable-speed power turbine (VSPT) offers one approach by which to effect this speed variation. VSPT aerodynamics challenges include high work factors at cruise, wide (40 to 60 ) incidence-angle variations in blade and vane rows over the speed range, and operation at low Reynolds numbers. Rotordynamics challenges include potential responsiveness to shaft modes within the 50 percent VSPT speed-range. A research effort underway at NASA Glenn Research Center, intended to address these key aerodynamic and rotordynamic challenges, is described. Conceptual design and 3-D multistage RANS and URANS analyses, conducted internally and under contract, provide expected VSPT sizing, stage-count, performance and operability information, and maps for system studies. Initial steps toward experimental testing of incidence-tolerant blading in a transonic linear cascade are described, and progress toward development/improvement of a simulation capability for multistage turbines with low Reynolds number transitional flow is summarized. Preliminary rotordynamics analyses indicate that viable concept engines with 50 percent VSPT shaft-speed range. Assessments of potential paths toward VSPT component-level testing are summarized.
    Keywords: Aerodynamics
    Type: NASA/TM-2012-217605 , E-18186
    Format: application/pdf
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    NASA TECHNICAL REPORTS
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