WIND TUNNEL AND LABORATORY TESTS ON THE EDCLIFF 4-15 ANGLE OF PITCH AND YAW TRANSDUCER
Yaw & pitch angle transducer - wind tunnel & laboratory tests at transonic and supersonic speeds
PITCHING MOMENT↗
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Curled-Skewed Wakes behind Yawed Wind Turbines Subject to Veered Inflow
This work presents a new engineering analytical model that predicts the effect of both the turbine yaw misalignment and the inflow wind veer on the wake flow distribution downwind of a wind turbine. To consider the veered inflow, two methods were examined. In the first method, the curled shape of the wake due to the yaw offset is initially modelled. The wake shape is then laterally skewed at each height due to the wind veer based on the assumption that the turbine wake is transported downstream by the incoming flow. The second method is a more realistic approach that accounts for the effect of wind veer on the wind velocity direction and the yaw angle seen by the wind turbine. This models the wake region in a local coordinate system defined based on the wind direction at each height. A coordinate transformation is then performed to represent the wake flow distribution in the global coordinate system attached to the ground. The results show that while the two methods provide similar outputs for small variations in the wind direction across the rotor, the difference becomes more evident with an increase in wind veer. High-fidelity simulations for a turbine subject to a neutral atmospheric boundary layer were employed to validate model predictions for different operating conditions.
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Experimental investigation of spherical-convergent-flap thrust-vectoring two-dimensional plug nozzles
An experimental investigation of multiaxis thrust vectoring nozzles with spherical convergent flaps (SCF) and a convertible (in-flight deployable) centerline plug were tested in the NASA-Langley 16-Foot Transonic Tunnel Static Test Facility. Parameters tested during the static test included plug length, external shroud length, shroud internal angle, and yaw vector angle. Results indicated that the SCF convertible-plug nozzle flow is highly three dimensional and characterized by internal flow separation and shock effects. The resultant thrust and discharge coefficient levels were lower than previous wedge nozzle results. In addition, increasing shroud internal angle increased resultant thrust ratio but decreased discharge coefficient. Increasing shroud length increased resultant thrust ratio performance for NPR's greater than 6.0 but for NPR's less than 6.0, resultant thrust ratio decreased as shroud length increased. Increasing plug length caused an increase in resultant thrust ratio and an increase in discharge coefficient. Increasing geometric yaw vector angle had no effect on resultant thrust ratio and little effect on discharge coefficient.
Cler, Daniel L.↗
Exploratory investigation of deflectable forebody strakes for high angle of attack yaw control
A deflectable strake concept was investigated on a conical forebody to evaluate its yaw control potential at high angles of attack. In exploratory low-speed tunnel tests using a generic delta wing fighter configuration, antisymmetrically deflected strakes provided useful levels of yaw power at angles of attack when the conventional rudder became totally degraded. Symmetrical strakes prevented side force development at high angles of attack, and provided pitch control through symmetrical deflection. The strake performance was sensitive to its circumferential position on the forebody due to varying interaction of strake vortices with the wing and vertical tail. The low Reynolds number results of this study provided a favorable initial validation of the concept, subject to verification in regard to scale effects.
Rao, D. M.↗
Impact dynamics research facility for full-scale aircraft crash testing
An impact dynamics research facility (IDRF) was developed to crash test full-scale general aviation aircraft under free-flight test conditions. The aircraft are crashed into the impact surface as free bodies; a pendulum swing method is used to obtain desired flight paths and velocities. Flight paths up to -60 deg and aircraft velocities along the flight paths up to about 27.0 m/s can be obtained with a combination of swing-cable lengths and release heights made available by a large gantry. Seven twin engine, 2721-kg aircraft were successfully crash tested at the facility, and all systems functioned properly. Acquisition of data from signals generated by accelerometers on board the aircraft and from external and onboard camera coverage was successful in spite of the amount of damage which occurred during each crash. Test parameters at the IDRF are controllable with flight path angles accurate within 8 percent, aircraft velocity accurate within 6 percent, pitch angles accurate to 4.25 deg, and roll and yaw angles acceptable under wind velocities up to 4.5 m/s.
Vaughan, V. L. J.↗
Results of a landing gear loads test using a 0.0405-scale model (16-0) of the space shuttle orbiter in the Rockwell International NAAL wind tunnel (OA163), volume 1
Experimental aerodynamic investigations were conducted on a sting mounted scale representation of the 140C outer mold line space shuttle orbiter configuration in the low speed wind tunnel. The primary test objectives were to define the orbiter landing gear system pressure loading and to record landing gear door and strut hingemoment levels. Secondary objectives included recording the aerodynamic influence of various landing gear configurations on orbiter force data as well as investigating 40 x 80 ft. Ames Wind Tunnel strut simulation effects on both orbiter landing gear loads and aerodynamic characteristics. Testing was conducted at a Mach number of 0.17, free stream dynamic pressure of 42.5 PSF, and Reynolds number per unit length of 1.2 million per foot. Angle of attack variation was 0 to 20 while yaw angles ranged from -10 to 10 deg.
Mennell, R. C.↗
Investigation of a Three-Dimensional Shock Wave Separated Turbulent Boundary Layer
A detailed Investigation of a flow in which a three-dimensional shock wave separates a two-dimensional turbulent boundary layer is presented. The resulting flowfield is highly three dimensional with a significant portion of flow separation on the surface at the phi = 0 deg (windward) plane was well as a large zone of secondary surface flow off this plane. Mean and fluctuating experimental measurements were obtained throughout the entire flowfield. These measurements included mean pressures, flow angles and shear on the surface, as well as yaw angles, static pressures, turbulent shear stresses, and turbulent kinetic energies on selected planes throughout the flowfield. In addition, numerical predictions of this flow, obtained by solving the Navier-Stokes equations with an algebraic eddy viscosity turbulence model, are presented. These computations reasonably predict both the surface and flowfield quantities, despite the extremely complicated nature of the experimental flow.
Kussoy, M. I.↗
Nonlinear Evolution and Breakdown of Azimuthally Compact Crossflow Vortex Pattern over a Yawed Cone
Hypersonic boundary-layer flows over a circular cone at moderate angle of incidence can support strong crossflow instability in between the windward and leeward rays on the plane of symmetry. Due to the more efficient excitation of stationary crossflow vortices by surface roughness, a possible path to transition in such flows corresponds to rapid amplification of the high-frequency secondary instabilities of finite amplitude stationary crossflow vortices. In the present paper, the previous analyses of crossflow instability over a 7- degree half-angle, yawed circular cone in a Mach 6 free stream have been extended to the nonlinear evolution of azimuthally localized crossflow vortex packets and the amplification characteristics and nonlinear breakdown of high-frequency secondary instabilities associated with those packets. A comparison between plane marching PSE and direct Navier-Stokes simulations (DNS) reveals favorable agreement in regard to mode shapes, most amplified disturbance frequencies, and N-factor evolution. In contrast, the quasi-parallel predictions are found to result in severe underprediction of the N-factors. The direct numerical simulations also indicate that the breakdown of secondary instabilities in a 3D hypersonic boundary layer shares certain common features with the previous computations of crossflow transition over subsonic swept wings.
Vortex structure↗
Stability and control characteristics for the inner mold line configuration of the space shuttle orbiter (OA110)
Experimental aerodynamic investigations were conducted on a sting mounted 0.0405-scale representation of the -140A/B inner mold line (IML) space shuttle orbiter in 7.75 x 11 foot low speed wind tunnel, during the time period from 18 March 1974 to 20 March 1974. The primary test objectives were to establish basic longitudinal and lateral-directional stability and control characteristics for the IML orbiter. Additional configurations investigated were sealed elevon hingeline gaps, sealed rudder split line and hingeline gaps, larger radius leading edge on the vertical tail, and sealed speedbrake base. Aerodynamic force and moment data for the orbiter were measured in the body-axis system by an internally mounted, six-component strain gage balance. The model was sting mounted with the center of rotation located at approximately the wing trailing edge. The nominal angle of attack range was from -4 to +30 degrees. Yaw polars were recorded over a nominal yaw angle range from -14 to +14 degrees at constant angles of attack of 0, + or - 5, 10, 15 and 20 degrees.
Hughes, T.↗
Heat-transfer tests on the Rockwell International space shuttle orbiter with and without simulated protuberances
Aerothermodynamic tests on the forward half of the Rockwell International Space Shuttle Orbiter Configuration 140C were conducted at Mach number 8. The phase-change paint and thin-skin thermocouple techniques were used to determine the aerodynamic heating rates on the Orbiter models during simulated atmospheric reentry. Smooth 0.04-scale models and models with scaled protuberances and indentations which simulated the windshields, cargo bay door hinges, vents, and thruster nozzles were tested over an angle-of-attack range from 20 to 45 deg at yaw angles from -5 to 5 deg and at Reynolds numbers, based on the total Orbiter scaled length, from 2.15 to 15.9 million. Comparisons of the model heat-transfer rates obtained with a smooth surface and with scaled protuberances are presented.
Carter, L. D.↗
A Study of TRMM Static Earth Sensor Performance Using On-Orbit Sensor Data
This paper presents the results of a study of the Barnes static Earth sensor assembly (ESA) using on-orbit data collected from the Tropical Rainfall Measuring Mission (TRMM) spacecraft. It is shown that there exist strong correlations between the large penetration angle residuals and the voltages produced by the Offset Radiation Source (ORS). It is conjectured that at certain times in the TRMM orbit the ORS is operating out of its calibrated range, and consequently corrupts the penetration angle information observed and processed by the ESA. The observed yaw drift between Digital Sun Sensor (DSS) observations is shown to be consistent with predictions by a simple roll-yaw coupling computation. This would explain the large drifts seen on TRMM, where the propagation of the yaw angle between DSS updates does not take into account the possibility of a non-zero roll angle error. Finally, the accuracy of the onboard algorithm used when only three of the four quadrants supply valid penetration angles is assessed. In terms of procedures used to perform this study, the analysis of ESA penetration angle residuals is discovered to be a very useful and insightful tool for assessing, the health and functionality of the ESA.
Natanson, Gregory↗
UAE6 - Wind Tunnel Tests Data - UAE6 - Sequence H - Raw Data
Sequences H, I, and J: Upwind Baseline (F), Upwind Low Pitch (F), Upwind High Pitch (F) This test sequence used an upwind, rigid turbine with a 0° cone angle. The wind speed ranged from 5 m/s to 25 m/s. Yaw angles of –30 to 180° were achieved at low wind speeds, and angles of ±10° were achieved for high wind speeds. The blade tip pitch was 3° for sequence H, 0° for sequence I, and 6° for sequence J. These three sequences were interleaved during testing because the pitch angle change was easily made by the turbine operator. The rotor rotated at 72 RPM. Blade and probe pressure measurements were collected. The teeter dampers were replaced with rigid links, and these two channels were flagged as not applicable by setting the measured values in the data file to –99999.99 Nm. The teeter link load cell was pretensioned to 40,000 N. In addition to the standard 30-second campaigns, yaw sweeps were done at 7 m/s and 10 m/s. These 6-minute campaigns were collected while the yaw drive rotated the turbine 360° at a rate of 1°/s. The file names for these campaigns use the letter designation, followed by two digits for wind speed, followed by YS, followed by 000.
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UAE6 - Wind Tunnel Tests Data - UAE6 - Sequence I - Raw Data
Sequences H, I, and J: Upwind Baseline (F), Upwind Low Pitch (F), Upwind High Pitch (F) This test sequence used an upwind, rigid turbine with a 0° cone angle. The wind speed ranged from 5 m/s to 25 m/s. Yaw angles of –30° to 180° were achieved at low wind speeds, and angles of ±10° were achieved for high wind speeds. The blade tip pitch was 3° for sequence H, 0° for sequence I, and 6° for sequence J. These three sequences were interleaved during testing because the pitch angle change was easily made by the turbine operator. The rotor rotated at 72 RPM. Blade and probe pressure measurements were collected. The teeter dampers were replaced with rigid links, and these two channels were flagged as not applicable by setting the measured values in the data file to –99999.99 Nm. The teeter link load cell was pre-tensioned to 40,000 N. In addition to the standard 30-second campaigns, yaw sweeps were done at 7 m/s and 10 m/s. These 6-minute campaigns were collected while the yaw drive rotated the turbine 360° at a rate of 1°/s. The file names for these campaigns use the letter designation, followed by two digits for wind speed, followed by YS, followed by 000.
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UAE6 - Wind Tunnel Tests Data - UAE6 - Sequence J - Raw Data
Sequences H, I, and J: Upwind Baseline (F), Upwind Low Pitch (F), Upwind High Pitch (F) This test sequence used an upwind, rigid turbine with a 0° cone angle. The wind speed ranged from 5 m/s to 25 m/s. Yaw angles of –30° to 180° were achieved at low wind speeds, and angles of ±10° were achieved for high wind speeds. The blade tip pitch was 3° for sequence H, 0° for sequence I, and 6° for sequence J. These three sequences were interleaved during testing because the pitch angle change was easily made by the turbine operator. The rotor rotated at 72 RPM. Blade and probe pressure measurements were collected. The teeter dampers were replaced with rigid links, and these two channels were flagged as not applicable by setting the measured values in the data file to –99999.99 Nm. The teeter link load cell was pre-tensioned to 40,000 N. In addition to the standard 30-second campaigns, yaw sweeps were done at 7 m/s and 10 m/s. These 6-minute campaigns were collected while the yaw drive rotated the turbine 360° at a rate of 1°/s. The file names for these campaigns use the letter designation, followed by two digits for wind speed, followed by YS, followed by 000.
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Measurement of post-separated flowfields on airfoils
A small combination pitch-yaw probe designed to facilitate measurement of post-separated flow fields on airfoils is described, along with its calibration. A five-tube probe is found 'ideally suited' to separated-flow measurements because of the pitch and yaw angle information provided in addition to static and total pressures. Wall proximity effects (in a low-speed tunnel) are described. Procedures for measurements in flows with small inclinations in pitch and yaw, for large flow angles, and for scanning flows with large inclinations are indicated.
Seetharam, H. C.↗
UAE6 - Wind Tunnel Tests Data - UAE6 - Sequence M - Raw Data
Sequence M: Transition Fixed (P) Test sequence M used an upwind, rigid turbine with a 0° cone angle. The wind speed ranged from 5 m/s to 15 m/s. Yaw angles ranged from 0° to 90°. The blade tip pitch was 3°. The rotor rotated at 72 RPM. Blade pressure measurements were collected. The five-hole probes were removed and the plugs were installed. Plastic tape 0.03-mm-thick was used to smooth the interface between the plugs and the blade. The teeter dampers were replaced with rigid links, and these two channels were flagged as not applicable by setting the measured values in the data file to –99999.99 Nm. The teeter link load cell was pre-tensioned to 40,000 N. During post-processing, the probe channels were set to read –99999.99. Zigzag tape was installed near the leading edge of the instrumented blade on both the upper and lower surfaces as described in Appendix K. In addition to the standard 30-second campaigns, yaw sweeps were done at 7 m/s and 10 m/s. These 90-second campaigns were collected while the yaw drive rotated the turbine 90° at a rate of 1°/s. The file names for these campaigns use the letter designation, followed by two digits for wind speed, followed by YSU, followed by 00.
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UAE6 - Wind Tunnel Tests Data - UAE6 - Sequence 4 - Raw Data
Sequence 4: Static Pressure Calibration (P) This test sequence used a downwind, teetered turbine with a 3.4° cone angle. The wind speed ranged from 5 m/s to 25 m/s. Yaw angles of 0° to 30° were achieved. The blade tip pitch was 3°. The rotor rotated at 72 RPM. Blade and probe pressure measurements were collected. A static pitot probe was installed on a boom 2.3 m upwind of the nacelle at hub height and connected to the reference side of the Mensor digital differential pressure transducer through the pneumatic rotary coupling. This provided the reference pressure for all blade-mounted pressure transducers, as opposed to the NASA atmospheric pressure reference that was used for all other test sequences. This simulates the pressure system connections used in field measurements where the static pressure was unknown.
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UAE6 - Wind Tunnel Tests Data - UAE6 - Sequence 8 - Raw Data
Sequences 8 and 9: Downwind Sonics (F,P) and Downwind Sonics Parked (P) This test sequence used an upwind, rigid turbine with a 0° cone angle. The wind speed ranged from 5 m/s to 25 m/s. Yaw angles of 0° to 60° were achieved. The blade tip pitch was 3°. The rotor rotated at 72 RPM during Sequence 8, but it was parked during Sequence 9. Blade pressure measurements were collected. The five-hole probes were removed and the plugs were installed. Plastic tape 0.03-mm-thick was used to smooth the interface between the plugs and the blade. The teeter dampers were replaced with rigid links, and these two channels were flagged as not applicable by setting the measured values in the data file to –99999.99 Nm. The teeter link load cell was pre-tensioned to 40,000 N. During post-processing, the probe channels were set to read -99999.99. Sonic anemometers were mounted on a strut downwind of the turbine. The strut was mounted to the T-frame, which was rotated to align the anemometers aft of the 9% and 49% radius locations at hub height. Because of this configuration, the tunnel balance data are considered invalid. Sequence 9 was designed to compare the downwind sonic anemometer readings with the upwind sonic anemometers without interference from the turbine. The rotor was parked with the instrumented blade at 0° azimuth. All pressure measurements obtained in Sequence 9 are invalid because sufficient time for temperature stabilization did not occur, thus all associated data values were flagged as not applicable by setting the measured values in the data file to 0.0000 Pa. This test is further described in Appendix G.
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