Structures and Interactions Underlying Rotational Augmentation of Blade Aerodynamic Response

2003 ◽  
Author(s):  
S. Schreck ◽  
M. Robinson
Keyword(s):  
Surface Pressure ◽  
Normal Force ◽  
Unsteady Aerodynamics ◽  
Boundary Layer Separation ◽  
Time Dependent ◽  
Blade Surface ◽  
Pressure Data ◽  
Pressure Distributions ◽  
Standard Deviations ◽  
Tunnel Time

Blade rotation routinely and significantly augments aerodynamic forces during zero yaw HAWT operation. To better understand the flow physics underlying this phenomenon, time dependent blade surface pressure data were acquired from the NREL Unsteady Aerodynamics Experiment, a full-scale HAWT tested in the NASA Ames 80 ft × 120 Ft wind tunnel. Time records of surface pressures and normal force were processed to obtain means and standard deviations. Surface pressure means and standard deviations were analyzed to identify boundary layer separation and reattachment locations. Separation and reattachment kinematics were then correlated with normal force behavior. Results showed that rotational augmentation was linked to specific separation and reattachment behaviors, and to associated three-dimensionality in surface pressure distributions.

Boundary Layer State and Flow Field Structure Underlying Rotational Augmentation of Blade Aerodynamic Response

2003 ◽  
Vol 125 (4) ◽  
pp. 448-456 ◽  
Author(s):  
S. Schreck ◽  
M. Robinson
Keyword(s):  
Boundary Layer ◽  
Surface Pressure ◽  
Normal Force ◽  
Unsteady Aerodynamics ◽  
Boundary Layer Separation ◽  
Pressure Data ◽  
Horizontal Axis Wind Turbine ◽  
Pressure Distributions ◽  
Standard Deviations ◽  
Tunnel Time

Blade rotation routinely and significantly augments aerodynamic forces during zero yaw horizontal axis wind turbine (HAWT) operation. To better understand the flow physics underlying this phenomenon, time dependent blade surface pressure data were acquired from the National Renewable Energy Laboratory (NREL). Unsteady Aerodynamics Experiment (UAE), a full-scale HAWT tested in the NASA Ames 80-by-120-foot wind tunnel. Time records of surface pressures and normal force were processed to obtain means and standard deviations. Surface pressure means and standard deviations were analyzed to identify boundary layer separation and shear layer impingement locations. Separation and impingement kinematics were then correlated with normal force behavior. Results showed that rotational augmentation was linked to specific separation and impingement behaviors, and to associated three-dimensionality in surface pressure distributions.

Surface Pressure Distribution on a Blade of a 10 m Diameter HAWT (Field Measurements versus Wind Tunnel Measurements)

2005 ◽  
Vol 127 (2) ◽  
pp. 185-191 ◽  
Author(s):  
T. Maeda ◽  
E. Ismaili ◽  
H. Kawabuchi ◽  
Y. Kamada
Keyword(s):  
Wind Tunnel ◽  
Surface Pressure ◽  
Field Measurements ◽  
Reynolds Numbers ◽  
Blade Surface ◽  
Pressure Data ◽  
Surface Pressure Distribution ◽  
Pressure Distributions ◽  
Wind Tunnel Data ◽  
Local Angle

This paper exploits blade surface pressure data acquired by testing a three-bladed upwind turbine operating in the field. Data were collected for a rotor blade at spanwise 0.7R with the rotor disc at zero yaw. Then, for the same blade, surface pressure data were acquired by testing in a wind tunnel. Analyses compared aerodynamic forces and surface pressure distributions under field conditions against analogous baseline data acquired from the wind tunnel data. The results show that aerodynamic performance of the section 70%, for local angle of attack below static stall, is similar for free stream and wind tunnel conditions and resemblances those commonly observed on two-dimensional aerofoils near stall. For post-stall flow, it is presumed that the exhibited differences are attributes of the differences on the Reynolds numbers at which the experiments were conducted.

Rotational Augmentation of Horizontal Axis Wind Turbine Blade Aerodynamic Response

2002 ◽  
Author(s):  
S. Schreck ◽  
M. Robinson
Keyword(s):  
Wind Turbine ◽  
Surface Pressure ◽  
Unsteady Aerodynamics ◽  
Horizontal Axis ◽  
Pressure Data ◽  
Aerodynamic Forces ◽  
Horizontal Axis Wind Turbine ◽  
Pressure Distributions ◽  
Rotating Blade ◽  
Wind Tunnel Data

Surface pressure data were acquired using the NREL Unsteady Aerodynamics Experiment, a full-scale horizontal axis wind turbine, which was erected in the NASA Ames 80 ft × 120 ft wind tunnel. Data were collected first for a stationary blade, and then for a rotating blade with the turbine disk at zero yaw. Analyses compared aerodynamic forces and surface pressure distributions under rotating conditions against analogous baseline data acquired from the stationary blade. This comparison allowed rotational modifications to blade aerodynamics to be characterized in detail. Rotating conditions were seen to dramatically amplify aerodynamic forces, and radically alter surface pressure distributions. These and subsequent findings will more fully reveal the structures and interactions responsible for these flow field enhancements, and help establish the basis for formalizing comprehension in physics based models.

scholarly journals Rocket Engine Turbine Blade Surface Pressure Distributions: Experiment and Computations

2003 ◽  
Vol 19 (3) ◽  
pp. 364-373 ◽  
Author(s):  
Susan T. Hudson ◽  
Thomas F. Zoladz ◽  
Daniel J. Dorney
Keyword(s):  
Turbine Blade ◽  
Surface Pressure ◽  
Rocket Engine ◽  
Blade Surface ◽  
Pressure Distributions

System to Measure the Pressure Distribution on Fan Aerofoil Surfaces During Flutter Conditions

1980 ◽  
Vol 102 (4) ◽  
pp. 427-432
Author(s):  
John W. H. Chivers
Keyword(s):  
Surface Pressure ◽  
High Speed ◽  
Cross Correlation ◽  
Test Results ◽  
Blade Surface ◽  
Pressure Data ◽  
Pressure Transducers ◽  
Induced Stress ◽  
Blade Tip ◽  
Typical Test

In order to assist in the understanding of high speed flutter, a series of tests has been conducted on a research fan in which the blade surface pressures have been measured by means of miniature silicon diaphragm pressure transducers embedded in selected fan blades. Prior to this investigation a program of rig tests was conducted to examine the effects of centrifugal force and vibration on the transducer performance and a transducer mounting technique was developed to minimize blade induced stress in the transducer. Instantaneous measurements of the tip stagger angles of the pressure instrumented fan blades have enabled a cross correlation to be performed on the blade surface pressure data and the blade tip angles. Some typical test results are shown.

Streamwise Fluidelastic Instability in a Deformed Rotated Triangular Tube Array With Pitch-to-Diameter Ratio of 1.375

2015 ◽  
Author(s):  
Daniel B. Keogh ◽  
Craig Meskell
Keyword(s):  
Surface Pressure ◽  
Diameter Ratio ◽  
Streamwise Direction ◽  
Pressure Data ◽  
Steam Generators ◽  
Drag Forces ◽  
Surface Pressure Distribution ◽  
Pressure Distributions ◽  
Fluidelastic Instability ◽  
Stable Flow

A study of the surface pressure distribution of a cylinder in a deformed rotated triangular tube array with pitch-to-diameter ratio of 1.375 has been performed. This work was motivated by the failure of steam generators in San Onofre Nuclear Generating Station (SONGS) in Southern California, which occurred as a result of fluidelastic instability in the streamwise direction. This particular failure occurred in the U-bend region of the steam generators. The presence of anti-vibration bars (AVB) in this region prevent the tubes from experiencing fluidelastic insatiably (FEI) in the transverse direction but offer little support in the streamwise direction. This study analyses the streamwise direction vibration of the tubes in the U-bend region using experimental data and a simplified quasi-steady model. Surface pressure data was gathered in a draw down wind tunnel for a range of flow velocities using an instrumented cylinder with 36 pressure taps around the circumference of the cylinder at midplane. The instrumented cylinder was mounted in the 4th and 6th rows of the tube array. The effect of streamwise displacement of up to ±10% of the instrumented tube and its neighbours was investigated. Although bi-stable flow was detected, only the forces in the lift direction were substantially affected. The displacement dependent drag forces acting on the instrumented cylinder were determined by integrating the pressure distributions with respect to angle. Hence the coupled fluid stiffness matrix could be assembled for each flow velocity studied. The effect of Reynolds number was also investigated for a number of scenarios.

Tip Speed Ratio Influences on Rotationally Augmented Boundary Layer Topology and Aerodynamic Force Generation

2004 ◽  
Vol 126 (4) ◽  
pp. 1025-1033 ◽  
Author(s):  
S. Schreck ◽  
M. Robinson
Keyword(s):  
Flow Field ◽  
Surface Pressure ◽  
Aerodynamic Force ◽  
Fluid Dynamic ◽  
Three Dimensional ◽  
Unsteady Aerodynamics ◽  
Speed Ratio ◽  
Pressure Data ◽  
Tip Speed Ratio ◽  
Normal Forces

Under zero yaw conditions, rotational effects substantially and routinely augment HAWT blade aerodynamic response. To better comprehend the fluid dynamic mechanisms underlying this phenomenon, time dependent blade surface pressure data were acquired from the National Renewable Energy Laboratory (NREL) Unsteady Aerodynamics Experiment (UAE), a full-scale HAWT tested in the NASA Ames 80 ft×120 ft wind tunnel. These surface pressure data were processed to obtain normal force and flow field topology data. Further analyses were carried out in a manner that allowed tip speed ratio effects to be isolated from other confounding influences. Results showed clear correlations between normal forces, flow field topologies, and tip speed ratios. These relationships changed significantly at different blade radial locations, pointing to the complex three-dimensional flow physics present on rotating HAWT blades.

Pressure-Sensitive Paint Investigation for Turbomachinery Application

1995 ◽  
Author(s):  
K. Sabroske ◽  
D. Rabe ◽  
C. Williams
Keyword(s):  
Surface Pressure ◽  
Rotor Blade ◽  
Ccd Camera ◽  
Pressure Sensitive Paint ◽  
Blade Surface ◽  
Pressure Data ◽  
Operational Environment ◽  
Suction Surface ◽  
Transonic Compressor ◽  
Pressure Sensitive

Two preliminary tests are discussed which investigate the feasibility of using pressure-sensitive paint (PSP) technology to acquire blade surface pressures in turbomachinery. The first test determined the prospect of using PSP in an operational environment. In this test, PSP was applied to a first stage rotor blade of a state-of-the-art transonic compressor. The paint survived the normal operating temperature, pressure, and centrifugal forces present in this compressor at rotational speeds up to 13,000 RPM. The second test investigated techniques to acquire blade surface pressure data. Suction surface intensity measurements were acquired from a low speed, high-aspect ratio compressor using a back illuminated charge coupled device (CCD) camera while the compressor was rotating at 1500 RPM. An optical derotating mechanism was used to hold the rotor blade image stationary while acquiring PSP data. Both experiments demonstrate that PSP is a viable technique to acquire blade surface pressure data in full scale compressor testing. Special considerations required in applying PSP techniques to turbomachinery are also reported.

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