Results are shown for a three-dimensional Navier-Stokes analysis of both the flow and the surface heat transfer for turbine applications. Heat transfer comparisons are made with the experimental shocktunnel data of Dunn and Kirn, and with the data of Blair for the rotor of the large scale rotating turbine. The analysis was done using the steady-state, three-dimensional, thin-layer Navier-Stokes code developed by Chlrna, which uses a multistage Runge-Kutta scheme with implicit residual smoothing. An algebraic mixing length turbulence model is used to calculate turbulent eddy viscosity. The variation in heat transfer due to variations in grid parameters is examined. The effects of rotation, tip clearance, and inlet boundary layer thickness variation on the predicted blade and endwall heat transfer are examined. Nomenclature Cp-Pressure coei_cient (P-P{N)/(PI_N-PSXIT) P-Pressure Re-Unit Reynolds number C-Chord s Fractionalsurfacedistance St-Stanton number based on inletconditions z Fractionalchordwise distance y Distance normal to surface _+-Normalized distancefrom surface 6 Full boundary layer thickness u Kinematic viscosity p Density fMember AIAA This paper isdeclared a work of the U.S. Government and isnot subjectto copyrightprotectionin the United States. Subscripts ¢-Gas total IN-Blade row inlet EXIT " Blade row hub exit w Wall 1-First gridlinefrom surface Superscript ' Total Form Approved REPORT DOCUMENTATION PAGE I OMB No. 0704-0188 i Public reporting burden "for this collection of information is estimated to average i hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection of information. Send comments regarding this bu_en est_ate or any other aspect o! this collection of information, including suggestions for reducing this burden, to Washington Headquatlers Services, Directorate for information Operations and Reports,
Aerodynamic measurements obtained in a transonic linear cascade were used to assess the impact of large incidence angle and Reynolds number variations on the 3-D flow field and midspan loss and turning of a 2-D section of a variable-speed power-turbine (VSPT) rotor blade. Steady-state data were obtained for ten incidence angles ranging from +15.8° to −51.0°. At each angle, data were acquired at five flow conditions with the exit Reynolds number (based on axial chord) varying over an order-of-magnitude from 2.12 × 105 to 2.12 × 106. Data were obtained at the design exit Mach number of 0.72 and at a reduced exit Mach number of 0.35 as required to achieve the lowest Reynolds number. Midspan total-pressure and exit flow angle data were acquired using a five-hole pitch/yaw probe surveyed on a plane located 7.0 percent axial-chord downstream of the blade trailing edge plane. The survey spanned three blade passages. Additionally, three-dimensional half-span flow fields were examined with additional probe survey data acquired at 26 span locations for two key incidence angles of +5.8° and −36.7°. Survey data near the endwall were acquired with a three-hole boundary-layer probe. The data were integrated to determine average exit total-pressure and flow angle as functions of incidence and flow conditions. The data set also includes blade static pressures measured on four spanwise planes and endwall static pressures. Tests were conducted in the NASA Glenn Transonic Turbine Blade Cascade Facility. The measurements reflect strong secondary flows associated with the high aerodynamic loading levels at large positive incidence angles and an increase in loss levels with decreasing Reynolds number. The secondary flows decrease with negative incidence as the blade becomes unloaded. Transitional flow is admitted in this low inlet turbulence dataset, making it a challenging CFD test case. The dataset will be used to advance understanding of the aerodynamic challenges associated with maintaining efficient power turbine operation over a wide shaft-speed range.
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% speed range from takeoff to altitude cruise. This results in 50° 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 5 to 0.8510 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% 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. NomenclatureCp s = static pressure coefficient,des M = Mach number PR = Pressure Ratio, PR P t,1 P 2 PS = Pressure Surface P = area-averaged static-pressure 2 t P = area-averaged total-pressure Re = Reynolds number, Re = ρU 1 C x /µ s = blade pitch [in] SS = suction surface U = total velocity x = chordwise (axial) direction y = tangential coordinate [in] Zw = Zweifel coefficient, Zw = 2s C x cos 2 2 (tan 1 tan 2 ) = relative flow angle [deg.] 2 = angle of mass-averaged velocity components δ = boundary layer thickness [in] µ = dynamic viscosity ρ = density = loss coefficient, ) /( ) ( 2 1 , 2 , 1 , P P P P t t t Subscripts des = design value 1 = cascade inlet value 2 = cascade exit value i = isentropic value
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