Experimental investigation in an annular cascade sector of highly loaded turbine stator blading. 5 - Performance of two tangential jet blades
Testing low reaction jet turbine stator blades in six-blade annular cascade
Bettner, J. L.↗
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Cold-air investigation of a turbine with transpiration-cooled stator blades. 3 - Performance of stator with wire-mesh shell blading
Performance of stator with wire mesh shell blading during cold air investigation of turbine with transpiration cooled stator blades - Vol. 3
Behning, F. P.↗
Overall and blade-element performance of a transonic compressor stage with multiple-circular-arc blades at tip speed of 419 meters per second
A 50-centimeter-diameter axial-flow transonic compressor stage with multiple-circular-arc blades was designed and tested to study the effects of blade shape on efficiency and stall margin. At design speed, peak efficiency of 0.80 occurred at an equivalent weight flow of 29.0 kilograms per second. Measured total pressure ratio and total temperature ratio at peak efficiency were 1.69 and 1.20, respectively. The stall margin at design speed and an equivalent weight flow of 29.0 kilograms per second was 9 percent. The measured stall margin at design weight flow and speed was 15 percent. A comparison of rotor performance made with and without the stator showed a decrease in pressure ratio, peak efficiency, and maximum weight flow with the addition of the stator.
Kovich, G.↗
Prediction of rotating-blade vortex noise from noise of nonrotating blades
Measurements were conducted in an acoustic wind tunnel to determine vortex noise of nonrotating circular cylinders and NACA 0012 airfoils. Both constant-width and spanwise tapered models were tested at a low turbulence level. The constant-diameter cylinder and constant-chord airfoil also were tested in the turbulent wake generated by an upstream cylinder or airfoil. Vortex noise radiation from nonrotating circular cylinders at Reynolds numbers matching those of the rotating-blade tests were found to be strongly dependent on surface conditions and Reynolds number. Vortex noise of rotating circular cylinder blades, operating with and without the shed wake blown downstream, could be predicted using data for nonrotating circular cylinders as functions of Reynolds number. Vortex noise of nonrotating airfoils was found to be trailing-edge noise at a time frequence equal to that predicted for maximum-amplitude Tollmein-Schlichting instability waves at the trailing edge.
Fink, M. R.↗
Bounds on thickness and loading noise of rotating blades and the favorable effect of blade sweep on noise reduction
The maxima of amplitudes of thickness and loading noise harmonics are established when the radial distribution of blade chord, thickness ratio, and lift coefficient is specified. It is first shown that only airfoils with thickness distribution and chordwise loading distributions which are symmetric with respect to midchord need be considered for finding the absolute maxima of thickness and loading noise. The resulting chordwise thickness and load distributions for these maximum noise conditions require infinite slope at some points along the chord but otherwise are uniform. It is shown that sweeping the blades reduces the thickness and loading noise, but there is no optimum sweep which generates the lowest noise.
Farassat, F.↗
Perturbation solutions for blade-to-blade surfaces of a transonic compressor
The paper describes a perturbation method for turbomachinery calculations, particularly where it is necessary to carry out a number of calculations for closely-related flows such as are needed in a parametric study. The method is applied for solving a model problem involving blade-to-blade surfaces of a transonic compressor. Basically, the method makes use of a previously calculated base solution to determine first-order changes in the flow field due to variations in one or more of a variety of geometrical or flow field parameters. The fundamental assumption associated with the perturbation solution is that the magnitude of the deviations from the base solution lies within the range of a linear perturbation analysis. Comparisons are made for results obtained, by varying the thickness ratio of an unstaggered nonlifting cascade composed of biconvex profiles in a flow with an oncoming freestream Mach number of 0.60.
Stahara, S. S.↗
Blade loading and spanwise effects on the near and far wake characteristics of a compressor rotor blade
An experimental investigation of the blade loading and spanwise effects on the rotor wake is presented. The investigation was limited to a study of a low subsonic and incompressible wake flow found downstream of a lightly loaded rotor. Measurements were made with a tri-axial hot wire probe mounted in the stationary frame of reference at six radial and nine axial positions. At each measurement location, the rotor was run at different operating conditions to discern the effects of blade loading on the wake. Near and far wake measurements are given, including mean velocity and turbulence intensity characteristics. The loading and spanwise effects on rotor wake characteristics were found to be substantial.
Reynolds, B.↗
Prediction of blade-vortex interaction noise from measured blade pressure
The impulsive nature of noise due to the interaction of a rotor blade with a tip vortex is studied. The time signature of this noise is calculated theoretically based on the measured blade surface pressure fluctuation of an operational load survey rotor in slow descending flight and is compared with the simultaneous microphone measurement. Particularly, the physical understanding of the characteristic features of a waveform is extensively studied in order to understand the generating mechanism and to identify the important parameters. The interaction trajectory of a tip vortex on an acoustic planform is shown to be a very important parameter for the impulsive shape of the noise. The unsteady nature of the pressure distribution at the very leading edge is also important to the pulse shape. The theoretical model using noncompact liner acoustics predicts the general shape of interaction impulse pretty well except for peak amplitude which requires more continuous information along the span at the leading edge.
Nakamura, Y.↗
A quasi-three-dimensional blade surface boundary layer analysis for rotating blade rows
A quasi-three-dimensional approximation has been developed for a blade boundary layer which involves the calculation of the effect of nonzero pressure gradients, turbulent flow, and blade twist, but includes only a simple coupling between streamlines. The resulting set of equations is solved using Keller's box scheme. The solution scheme is checked against available incompressible flow solutions and then applied to a NASA low aspect ratio transonic compressor stage for which extensive experimental and computational data are available. It is found that the three-dimensional boundary layer separates significantly sooner and has a much larger influence on rotor performance than would be expected from a two-dimensional analysis.
Thompkins, W. T., Jr.↗
Prediction of blade vortex interaction noise from measured blade pressure
The impulsive nature of noise due to the interaction of a rotor blade with a tip vortex is studied. The time signature of this noise is calculated theoretically based on the measured blade surface pressure fluctuation of an operational load survey rotor in slow descending flight and is compared with the simultaneous microphone measurement. Particularly, the physical understanding of the characteristic features of a waveform is extensively studied in order to understand the generating mechanism and to identify the important parameters. The interaction trajectory of a tip vortex on an acoustic planform is shown to be a very important parameter for the impulsive shape of the noise. The unsteady nature of the pressure distribution at the very leading edge is also important to the pulse shape. The theoretical model using noncompact linear acoustics predicts the general shape of interaction impulse pretty well except for peak amplitude which requires more continuous pressure information along the span at the leading edge.
Nakamura, Y.↗
Dynamics of an experimental two bladed horizontal axis wind turbine with blade cyclic pitch variation
The turbine under study incorporates the combination of two features: the application of blade cyclic pitch variation; and the use of yaw angle control for rotor speed and torque regulation. Due to its emasculation by passive cyclic pitch variation the rotor can be rapidly yawed without encountering gyroscopic and aerodynamic hub moments and without noticeable out of plane excursions. The two bladed upwind rotor is vane stabilized and of very simple and rugged design. The principle was first checked out with a small scale wind tunnel model and then tested in the atmosphere with a 7.6 meter diameter experimental fully instrumented wind turbine driving a 3 phase alternator. The test results are summarized with respect to structural dynamics and yaw dynamics.
Hotenemser, K. H.↗
A rapid blade-to-blade solution for use in turbomachinery design
A rapid technique for solving the blade-to-blade turbomachinery flow problem was developed. Approximate governing flow equations, which include the effects of compressibility, radius change, rotation, and variable stream sheet thickness are solved using a panel method. The development and solution of these equations are described. Sample calculations are presented to illustrate the method's capabilities and accuracy.
Mcfarland, E. R.↗
A rapid blade-to-blade solution for use in turbomachinery design
A rapid technique for solving the blade-to-blade turbomachinery flow problem was developed. Approximate governing flow equations, which include the effects of compressibility, radius change, rotation, and variable stream sheet thickness are solved using a panel method. The development and solution of these equations are described. Sample calculations are presented to illustrate the method's capabilities and accuracy. Previously announced in STAR as N83-13077
Mcfarland, E. R.↗
Prediction of blade-vortex interaction noise using measured blade pressures
In the study reported here, blade-vortex interaction noise was predicted using a simplified model of blade pressures measured on a one-seventh scale model AH-1/OLS main rotor. The methods used for the acoustic prediction are based on the acoustic analogy and have been developed by Nakamura (1981) and by Brentner, Nystrom, and Farassat (referred to as the WOPWOP method). The waveforms predicted by the two methods are in good agreement with each other and with the measurements in terms of the number of pulses, the pulse widths, and the separation times between the pulses. The peak amplitude of the dominant pulse may, however, be underpredicted by up to 40 percent, depending on flight conditions. Ways of improving the accuracy of the prediction methods are suggested.
Joshi, Mahendra C.↗
Altitude-Wind-Tunnel Investigation of Performance of Several Propellers on YP-47M Airplane at High Blade Loadings: Curtiss 732-1C2-0 Four-Blade Propeller - 4
An altitude-wind-tunnel investigation has been made to determine the performance of a Curtiss 732-1C2-0 four-blade propeller on a YP-47M airplane at high blade loadings and engine power. Propeller characteristics were obtained for a range of power coefficients from 0.30 to 1.00 at free-stream Mach numbers of 0.40 and .50.
Saari, Martin J.↗
Effect of Various Blade Modifications on Performance of a 16-Stage Axial-Flow Compressor. III - Effect on Over-All Performance Characteristics on Increasing Stator-Blade Angles in Inlet Stages
The stator-blade angles in the first four stages of a 16-stage axial-flow compressor were increased in order to decrease the angles of attack of these stages, and thereby to improve part-speed performance. The performance of this modified compressor was compared with that of the same compressor with original blade angles.
Medeiros, Arthur A.↗
Use of arbitrary quasi-orthogonals for calculating flow distribution on a blade-to- blade surface in a turbomachine
Turbomachine blade surface flow distribution analysis by arbitrary quasi-orthogonals - radial inflow turbine Fortran computer program
FORTRAN↗
Blade element performance of axial-flow pump rotor with blade tip diffusion factor of 0.66
Radial distributions and parameters of flow across blade elements of axial flow pump rotor measured in water
FLOW MEASUREMENT↗