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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 55 records · Page 3
All sourcesNASA NTRSDOE OSTI
NASA NTRS1978

Two-dimensional cold-air cascade study of a film-cooled turbine stator blade. 4: Comparison of experimental and analytical aerodynamic results for blade with 12 rows of 0.076-centimeter-(0.030-inch-) diameter holes having streamwise ejection angles

Previously published experimental aerodynamic efficiency results for a film cooled turbine stator blade are compared with analytical results computed from two published analytical methods. One method was used as published; the other was modified for certain cases of coolant discharge from the blade suction surface. For coolant ejection from blade surface regions where the surface static pressures are higher than the blade exit pressure, both methods predict the experimental results quite well. However, for ejection from regions with surface static pressures lower than the blade exit pressure, both methods predict too small a change in efficiency. The modified method gives the better prediction.

Prust, H. W., Jr.↗
NASA NTRS1985

Turbine blade thermal fatigue testing Pratt and Whitney aircraft hollow core blades

The results of low cycle fatigue testing on turbine blades for use in hydrogen/oxygen rocket engines is presented. Cored blade and cored blades with circulation were tested in the MSFC thermal fatigue tester. Both blade configurations showed significant low cycle fatigue life improvements when compared to baseline solid blades.

Ingram, J.↗
NASA NTRS1987

Estimation of blade airloads from rotor blade bending moments

A method is developed to estimate the blade normal airloads by using measured flap bending moments; that is, the rotor blade is used as a force balance. The blade's rotation is calculated in vacuum modes and the airloads are then expressed as an algebraic sum of the mode shapes, modal amplitudes, mass distribution, and frequency properties. The modal amplitudes are identified from the blade bending moments using the Strain Pattern Analysis Method. The application of the method is examined using simulated flap bending moment data that have been calculated for measured airloads for a full-scale rotor in a wind tunnel. The estimated airloads are compared with the wind tunnel measurements. The effects of the number of measurements, the number of modes, and errors in the measurements and the blade properties are examined, and the method is shown to be robust.

Bousman, William G.↗
NASA NTRS1951

Investigation of Mechanisms of Blade Failure of Forged Hastalloy B and Cast Stellite 21 Turbine Blades in Turbojet Engine

An investigation was conducted to study the mechanisms of blade failure of forged Hastelloy B and cast Stellite 21. The blades were mounted in a 16-25-6 alloy rotor and subjected to 20-minute cycles consisting of 15 minutes at rated speed and approximately 5 minutes at idle. The first failures of the Hastelloy B and Stellite 21 blades were probably the result of excessive vibratory stresses and occurred after 14.25 and 16.75 hours, respectively. After 28.75 hours of operation, all but 3 of the original 25 Hastelloy B blades had either failed or contained stress-rupture-type cracks and four of the original 27 Stellite 21 blades contained stress-rupture-type cracks.

ENGINES, TURBO-JET↗
NASA NTRS1920

The general theory of blade screws including propellers, fans, helicopter screws, helicoidal pumps, turbo-motors, and different kinds of helicoidal blades

Report presents a theory which gives a complete picture and an exact quantitative analysis of the whole phenomenon of the working of blade screws, but also unites in a continuous whole the entire scale of states of work conceivable for a blade screw. Chapter 1 is devoted to the establishment of the system of fundamental equations relating to the blade screw. Chapter 2 contains the general discussion of the 16 states of work which may establish themselves for a blade screw. The existence of the vortex ring state and the whirling phenomenon are established. All the fundamental functions which enter the blade-screw theory are submitted to a general analytical discussion. The general outline of the curve of the specific function is examined. Two limited cases of the work of the screw, the screw with a zero constructive pitch and the screw with an infinite constructive pitch, are pointed out. Chapter 3 is devoted to the study of the propulsive screw or propeller. (author)

De Bothezat, George↗
NASA NTRS1994

Experimental measurements and analytical analysis related to gas turbine heat transfer. Part 1: Time-averaged heat-flux and surface-pressure measurements on the vanes and blades of the SSME fuel-side turbine and comparison with prediction. Part 2: Phase-resolved surface-pressure and heat-flux measurements on the first blade of the SSME fuel-side turbine

Time averaged Stanton number and surface-pressure distributions are reported for the first-stage vane row, the first stage blade row, and the second stage vane row of the Rocketdyne Space Shuttle Main Engine two-stage fuel-side turbine. Unsteady pressure envelope measurements for the first blade are also reported. These measurements were made at 10 percent, 50 percent, and 90 percent span on both the pressure and suction surfaces of the first stage components. Additional Stanton number measurements were made on the first stage blade platform blade tip, and shroud, and at 50 percent span on the second vane. A shock tube was used as a short duration source of heated and pressurized air to which the turbine was subjected. Platinum thin-film heat flux gages were used to obtain the heat flux measurements, while miniature silicon-diaphragm flush-mounted pressure transducers were used to obtain the pressure measurements. The first stage vane Stanton number distributions are compared with predictions obtained using a version of STAN5 and a quasi-3D Navier-Stokes solution. This same quasi-3D N-S code was also used to obtain predictions for the first blade and the second vane.

Source record↗
NASA NTRS1961

Investigation of the Performance of an Axial-Flow-Pump Stage Designed by the Blade-Element Theory: Blade-Element Data

An axial-flow-pump stage was designed by utilizing blade-element methods in conjunction with axial-flow-compressor blade-element theory. This report presents the blade-element data of the pump stage in both the noncavitating and cavitating conditions. The noncavitating blade- element performance is compared with design rules. The results indicated that some modification of the compressor design equations for computing minimum-loss incidence and deviation angles may be necessary for application to an axial-flow-pump design. Minimum values of observed rotor loss were slightly lower than anticipated from compressor results. At the design flow coefficient the rotor-blade elements were not operating at the reference incidence angles, and the experimental efficiency was lower than the design value. The observed head rise was very close to the design. An attempt was made to estimate the potential of this rotor by using the minimum measured values of loss coefficient and observed energy input at the design flow. Performance of the pump at a suction specific speed of approximately 13,000 (cavitation number k approximately equals 0.12) showed only a slight dropoff in performance in the cavitation inception region from the noncavitating results. The observed performance at a suction specific speed of approximately 16,000 (k approximately equals 0.09) is also presented for comparison.

Crouse, James E.↗
NASA NTRS2003

Estimating Blade Section Airloads from Blade Leading-Edge Pressure Measurements

The Tilt-Rotor Aeroacoustic Model (TRAM) test in the Duitse-Nederlandse Wind (DNW) Tunnel acquired blade pressure data for forward flight test conditions of a tiltrotor in helicopter mode. Chordwise pressure data at seven radial locations were integrated to obtain the blade section normal force. The present investigation evaluates the use of linear regression analysis and of neural networks in estimating the blade section normal force coefficient from a limited number of blade leading-edge pressure measurements and representative operating conditions. These network models are subsequently used to estimate the airloads at intermediate radial locations where only blade pressure measurements at the 3.5% chordwise stations are available.

vanAken, Johannes M.↗
NASA NTRS1992

Blade lock for a rotor disk and rotor blade assembly

A rotor disk 18 and rotor blade 26 assembly is disclosed having a blade lock 66 which retains the rotor blade against axial movement in an axially extending blade retention slot 58. Various construction details are developed which shield the dead rim region D.sub.d and shift at least a portion of the loads associated with the locking device from the dead rim. In one detailed embodiment, a projection 68 from the live rim D.sub.1 of the disk 18 is adapted by slots 86 to receive blade locks 66.

Moore, Jerry H.↗
NASA NTRS2005

Rotor blade system with reduced blade-vortex interaction noise

A rotor blade system with reduced blade-vortex interaction noise includes a plurality of tube members embedded in proximity to a tip of each rotor blade. The inlets of the tube members are arrayed at the leading edge of the blade slightly above the chord plane, while the outlets are arrayed at the blade tip face. Such a design rapidly diffuses the vorticity contained within the concentrated tip vortex because of enhanced flow mixing in the inner core, which prevents the development of a laminar core region.

Leishman, John G.↗
NASA NTRS2006

Blade-to-Blade Variations in Shocks Upstream of Both a Forward-Swept and an Aft-Swept Fan

Detailed laser Doppler velocimeter (LDV) flow field measurements were made upstream of two fans, one forward-swept and one aft-swept, in order to learn more about the shocks which propagate upstream of these rotors when they are operated at supersonic tip speeds. The blade-to-blade variations in the flows associated with these shocks are thought to be responsible for generating Multiple Pure Tone (MPT) noise. The measured blade-to-blade variations are documented in this report through a series of slideshows which show relative Mach number contours computed from the velocity measurements. Data are presented for the forward-swept fan operating at three speeds (corresponding to tip relative Mach numbers of 0.817, 1.074, and 1.189), and for the aft-swept fan operating at two (tip relative Mach numbers of 1.074 and 1.189). These LDV data illustrate how the perturbations in the upstream flow field created by the rotating blades vary with axial position, radial position and rotor speed. As expected, at the highest tested speed the forward-swept fan swallowed the shocks which occur in the tip region, whereas the aftswept fan did not. This resulted in a much smaller flow disturbance just upstream of the tip of the forward-swept fan. Nevertheless, further upstream the two fan flows were much more similar.

Podboy, Gary G.↗
NASA NTRS1940

Photographic Observations of Blade Motion of the YG-1B Autogiro Equipped with Tapered Rotor Blades

This report presents the results of photographic observations in flight of the flapping, the motion about the vertical pin, and the dynamic twist of a new type tapered rotor blade on the Kellett YG-1B autogiro. The blades, which were designed by the Kellett Autogiro Corporation, made use of the NACA 230 series airfoil section, for the purpose of eliminating undesirable dynamic blade twist present in the original blades. The results reported herein show that in actual operation the new blades very closely approach the desired condition of no dynamic twist.

Bailey, F. J., Jr.↗
NASA NTRS1953

Aerodynamic Characteristics of a Two-blade NACA 10-(3)(062)-045 Propeller and of a Two-blade NACA 10-(3)(08)-045 Propeller

Characteristics are given for the two-blade NACA 10-(3)(062)-045 propeller and for the two-blade NACA 10-(3)(08)-045 propeller over a range of advance ratio from 0.5 to 3.8, through a blade-angle range from 20 degrees to 55 degrees measured at the 0.75 radius. Maximum efficiencies of the order of 91.5 to 92 percent were obtained for the propellers. The propeller with the thinner airfoil sections over the outboard portion of the blades, the NACA 10-(3)(062)-045 propeller, had lower losses at high tip speeds, the difference amounting to about 5 percent at a helical tip Mach number of 1.10.

BLADE SECTIONS-PROPELLERS↗
NASA NTRS1981

Improved method for calculating transonic velocities on blade-to-blade stream surfaces of a turbomachine

A method was developed to improve the accuracy of an existing computer program used to calculate transonic velocities on a blade-to-blade surface of a turbomachine. The method eliminates problems encountered in obtaining solutions with the velocity gradient equation when large gradients in velocity occur through the blade row. With the improved method, results indicate that the transonic solution can be obtained by scaling the velocities obtained at the reduced mass flow rate where all velocities are subsonic thereby eliminating the need for a solution of the velocity gradient equation. Solutions obtained with the scaling method on a two dimensional compressor cascade and an axial turbine stator show good agreement with experimental data. The results obtained for the stationary blade rows and comparison of analytical results obtained with and without the present method suggest that the method will yield an improved solution for centrifugal compressor impellers.

Wood, J. R.↗
NASA NTRS1983

Blade loss transient dynamics analysis with flexible bladed disk

The transient dynamic response of a flexible bladed disk on a flexible rotor in a two rotor system is formulated by modal synthesis and a Lagrangian approach. Only the nonequilibrated one diameter flexible mode is considered for the flexible bladed disk, while the two flexible rotors are represented by their normal modes. The flexible bladed disk motion is modeled as a combination of two one diameter standing waves, and is coupled inertially and gyroscopically to the flexible rotors. Application to a two rotor model shows that a flexible bladed disk on one rotor can be driven into resonance by an unbalance in the other rotor, and at a frequency equal to the difference in the rotor speeds.

Gallardo, V. C.↗
NASA NTRS1986

Effects of blade-to-blade dissimilarities on rotor-body lead-lag dynamics

Small blade-to-blade property differences are investigated to determine their effects on the behavior of a simple rotor-body system. An analytical approach is used which emphasizes the significance of these effects from the experimental point of view. It is found that the primary effect of blade-to-blade dissimilarities is the appearance of additional peaks in the frequency spectrum which are separated from the convention response modes by multiples of the rotor speed. These additional responses are potential experimental problems because when they occur near a mode of interest they act as contaminant frequencies which can make damping measurements difficult. The effects of increased rotor-body coupling and a rotor shaft degree of freedom act to improve the situation by altering the frequency separation of the modes.

Mcnulty, M. J.↗
NASA NTRS1985

Vibrations of blades and bladed disk assemblies; Proceedings of the Tenth Biennial Conference on Mechanical Vibration and Noise, Cincinnati, OH, September 10-13, 1985

The papers presented in this volume provide an overview of recent theoretical and analytical research in bladed disk assemblies, with particular attention given to forced response, mistuning, and damping. Specific topics discussed include the response of mistuned bladed disk assemblies; forced response analysis of an aerodynamically detuned supersonic turbomachine rotor; dynamic analysis of blade groups using component mode synthesis; and pendulum dynamic vibration absorbers for reducing blade vibration in industrial fans.

Kielb, R. E.↗
NASA NTRS1985

Effects of blade-to-blade dissimilarities on rotor-body lead-lag dynamics

Small blade-to-blade property differences are investigated to determine their effects on the behavior of a simple rotor-body system. An analytical approach is used which emphasizes the significance of these effects from the experimental point of view. It is found that the primary effect of blade-to-blade dissimilarities is the appearance of additional peaks in the frequency spectrum which are separated from the conventional response modes by multiples of the rotor speed. These additional responses are potential experimental problems because when they occur near a mode of interest they act as contaminant frequencies which can make damping measurements difficult. The effects of increased rotor-body coupling and a rotor shaft degree of freedom act to improve the situation by altering the frequency separation of the modes.

Mcnulty, Michael J.↗