Thrust Characteristics of Cycloidal Propeller and Flow Measurement

Now airships are expected to be used as drones for support services at disasters and global environment monitors. However, such applications have not been successfully attained due to the vehicle’s poor kinetic performances. Our team, then, tries to improve the kinetic performances of airships by installing cycloidal propellers which can instantly change thrusts toward arbitrarily directions by controlling attack angles of the rotor blades. In this study, we report results of static thrust measurement experiment of a cycloidal propeller for 10-meter class airships, and wind tunnel tests and flow measurements around a rotor by the particle image velocimetry (PIV) applying to a miniature cycloidal propeller. The radius of rotor, the chord and the span of blades, the number of blade of the cycloidal propeller for 10-meter class airships are respectively 0.4m, 0.3m, 0.5m, and 3, and those values for the miniature cycloidal propeller are respectively 0.16m, 0.12m, 0.2m, and 3. Firstly it was found that the cycloidal propeller for 10-meter class airships can generate 50N as the maximum thrust at a rotational speed of 8 rps and with attack angle of 25 degrees. Moreover, thrust directions deviate from instructed directions toward the rotational direction by 25 degrees at the maximum. Secondly, from the wind tunnel test, thrust coefficients were found to be decreasing as advance ratios increase, which corresponds to a tendency of general type propellers. In addition, it was clarified that the propeller intakes the air not only from the rotating surface of the propeller but also from the rotor axial direction of the propeller by visualizing the air flow around the rotor by PIV.

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An Historical and Applied Aerodynamic Study of the Wright Brothers’ Wind Tunnel Test Program and Application to Successful Manned Flight

Volume 1: Symposia, Parts A and B ◽

10.1115/fedsm2005-77256 ◽

2005 ◽

Cited By ~ 1

Author(s):

Michael G. Dodson ◽

David S. Miklosovic

Keyword(s):

Wind Tunnel ◽

Wind Tunnel Test ◽

Scaling Effects ◽

Force Measurements ◽

Velocity Gradients ◽

Tunnel Model ◽

Image Velocimetry ◽

Manned Flight ◽

Flow Quality ◽

Scale Design

A replica wind tunnel was built and used to test the flow quality through the Wright Brothers’ wind tunnel. The research determined the effect flow quality and experimental method had on the Brothers’ results, and whether those results were useful in a quantitative sense. Particle image velocimetry revealed boundary layers extending 2.5” (63.5 mm) from each wall, and velocity gradients as large as 20% along the wind tunnel model span resulting in an asymmetric lift distribution. Similarly, the balance generated asymmetric wingtip vortices contributing to asymmetric downwash along the span of the model. Direct force measurements of a replica of the Wrights #12 airfoil showed their lift measurements were at least 7% and as much as 15% too low, and numerical analysis revealed wind tunnel predictions for lift, drag, and efficiency were not applicable to full scale design due to Reynolds number scaling effects.

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Wind Tunnel Test of the S814 Thick Root Airfoil

Journal of Solar Energy Engineering ◽

10.1115/1.2871781 ◽

1996 ◽

Vol 118 (4) ◽

pp. 217-221 ◽

Cited By ~ 10

Author(s):

D. M. Somers ◽

J. L. Tangler

Keyword(s):

Wind Tunnel ◽

Lift Coefficient ◽

Wind Tunnel Test ◽

Leading Edge ◽

Reynolds Numbers ◽

Rotor Blades ◽

Roughness Effects ◽

Root Region ◽

University Of Technology ◽

Thick Airfoil

The objective of this wind-tunnel test was to verify the predictions of the Eppler Airfoil Design and Analysis Code for a very thick airfoil having a high maximum lift coefficient designed to be largely insensitive to leading-edge roughness effects. The 24 percent thick S814 airfoil was designed with these characteristics to accommodate aerodynamic and structural considerations for the root region of a wind-turbine blade. In addition, the airfoil’s maximum lift-to-drag ratio was designed to occur at a high lift coefficient. To accomplish the objective, a two-dimensional wind tunnel test of the S814 thick root airfoil was conducted in January 1994 in the low-turbulence wind tunnel of the Delft University of Technology Low Speed Laboratory, The Netherlands. Data were obtained with transition free and transition fixed for Reynolds numbers of 0.7, 1.0, 1.5, 2.0, and 3.0 × 106. For the design Reynolds number of 1.5 × 106, the maximum lift coefficient with transition free is 1.32, which satisfies the design specification. However, this value is significantly lower than the predicted maximum lift coefficient of almost 1.6. With transition fixed at the leading edge, the maximum lift coefficient is 1.22. The small difference in maximum lift coefficient between the transition-free and transition-fixed conditions demonstrates the airfoil’s minimal sensitivity to roughness effects. The S814 root airfoil was designed to complement existing NREL low maximum-lift-coefficient tip-region airfoils for rotor blades 10 to 15 meters in length.

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Extraction and imaging of aerodynamically generated sound field of rotor blades in the wind tunnel test

Mechanical Systems and Signal Processing ◽

10.1016/j.ymssp.2018.07.042 ◽

2019 ◽

Vol 116 ◽

pp. 1017-1028 ◽

Cited By ~ 2

Author(s):

Liang Yu ◽

Haijun Wu ◽

Jerome Antoni ◽

Weikang Jiang

Keyword(s):

Wind Tunnel ◽

Wind Tunnel Test ◽

Sound Field ◽

Rotor Blades

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Wind Tunnel Tests of Influence of Boosters and Fins on Aerodynamic Characteristics of the Experimental Rocket Platform

Transactions on Aerospace Research ◽

10.2478/tar-2017-0030 ◽

2017 ◽

Vol 2017 (4) ◽

pp. 82-102

Author(s):

Paweł Ruchała ◽

Robert Placek ◽

Wit Stryczniewicz ◽

Jan Matyszewski ◽

Dawid Cieśliński ◽

...

Keyword(s):

Wind Tunnel ◽

Aerodynamic Drag ◽

Wind Tunnel Test ◽

Longitudinal Axis ◽

Aerodynamic Characteristics ◽

Scale Model ◽

Wind Tunnel Tests ◽

Aerodynamic Loads ◽

Microgravity Experiments ◽

Image Velocimetry

Abstract The paper presents results of wind tunnel tests of the Experimental Rocket Platform (ERP), which is developed in Institute of Aviation. It is designed as an easy accessible and affordable platform for microgravity experiments. Proposed design enables to perform experiments in microgravity for almost 150 seconds with apogee of about 100 km. The full-scale model of the ERP has been investigated in the T-3 wind tunnel in Institute of Aviation. During the investigation, the aerodynamic loads of the rocket has been measured for the angle of attack up to 10° and the different rotation angle around the longitudinal axis (up to 90°, depending on the configuration). Three configurations has been investigated: • without fins and boosters • with fins and without boosters • with fins and boosters Additionally, the measurements of velocity field around the ERP using the Particle Image Velocimetry (PIV) has been performed. Based on the wind tunnel test, an influence of fins and boosters on aerodynamic characteristics of the rocket has been described. Results of the wind tunnel tests show relatively high contribution of boosters in total aerodynamic drag. Some conclusions concerning performance and stability of the rocket have been presented.

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Full-Field Displacement Measurements of Helicopter Rotor Blades Using Stereophotogrammetry

International Journal of Aerospace Engineering ◽

10.1155/2021/8811601 ◽

2021 ◽

Vol 2021 ◽

pp. 1-18

Author(s):

Chenglin Zuo ◽

Chunhua Wei ◽

Jun Ma ◽

Tingrui Yue ◽

Lei Liu ◽

...

Keyword(s):

Wind Tunnel ◽

Coordinate System ◽

Wind Tunnel Test ◽

Rotor Blades ◽

Measuring System ◽

Helicopter Rotor ◽

Full Field ◽

Field Displacement ◽

Helicopter Rotor Blades ◽

Displacement Measurements

This study presents a stereophotogrammetry approach to achieve full-field displacement measurements of helicopter rotor blades. The method is demonstrated in the wind tunnel test of a 2 m diameter rotor, conducted at the 5.5 m × 4 m Aeroacoustic Wind Tunnel of China Aerodynamics Research and Development Center (CARDC). By arranging the retroreflective targets on the special hat installed directly above the rotor hub, the dynamic motion of the rotor shaft was tracked accurately, and a unified coordinate system was established on the rotor. Therefore, three-dimensional coordinates of instantaneously measured targets attached on the blade could be transformed to the unified rotor coordinate system, thereby providing a basis for consistently calculating the blade displacements at different test conditions. Moreover, location deviations of the blade caused by the vibration of the measuring system or the rotor due to freestream and rotor rotation were also effectively corrected through coordinate transformation. Comparisons of experimental and simulation results for a range of hover and forward flight conditions show good magnitude and trend agreements.

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Blade Structural Load/Airload Correlation on a Slowed Mach-Scaled Rotor at High Advance Ratios

Journal of the American Helicopter Society ◽

10.4050/jahs.65.042003 ◽

2020 ◽

Vol 65 (4) ◽

pp. 1-14

Author(s):

Xing Wang ◽

Yong Su Jung ◽

James Baeder ◽

Inderjit Chopra

Keyword(s):

Wind Tunnel ◽

Structural Model ◽

Reverse Flow ◽

Pressure Sensors ◽

Wind Tunnel Test ◽

Design Feature ◽

Flow Region ◽

Rotor Blades ◽

Data Correlation ◽

Advance Ratio

To expand the cruise speed of a compound helicopter, alleviating the compressibility effects on the advancing side with reduced rotor RPM is proved to be an effective design feature, which results in high advance ratio flight regime. To investigate the aerodynamic phenomena at high advance ratios and provide data for the validation of analytical tools, a series of wind tunnel tests were conducted progressively in the Glenn L. Martin Wind Tunnel with a 33.5-inch radius fourbladed articulated rotor. In a recent wind tunnel test, the rotor blades were instrumented with pressure sensors and strain gauges at 30% radius, and pressure data were acquired to calculate the sectional airloads by surface integration up to an advance ratio of 0.8. The experimental results of rotor performance, control angles, blade airloads, and structural loads were compared with the predictions of comprehensive analysis and computational fluid dynamics (CFD) analysis coupled with computational structural dynamics (CSD) structural model. The paper focuses on the data correlation between experimental pressure, airload, and structural load data and the CFD/CSD predicted results at various collective and shaft tilt angles. Overall, the data correlation was found satisfactory, and the study provided some insights into the aerodynamic mechanisms that affect the rotor airload and performance, in particular the mechanisms of backward shaft tilt, the effect of hub/shaft wake, and the formation of dynamic stall in the reverse flow region.

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Effects of the Rotor Tip Leakage in a Transonic Turbine With Long Blades

Volume 1: Turbomachinery ◽

10.1115/98-gt-096 ◽

1998 ◽

Author(s):

Miroslav Št’astný ◽

Richard Matas ◽

Pavel Šafařík ◽

Alexander R. Jung ◽

Jürgen F. Mayer ◽

...

Keyword(s):

Wind Tunnel ◽

Three Dimensional ◽

Rotor Blades ◽

Navier Stokes ◽

Turbine Stage ◽

Tip Leakage Flow ◽

Navier Stokes Equation ◽

Flow Measurements ◽

Tip Leakage ◽

Transonic Turbine

A study of the flow in a transonic turbine stage with long and strongly twisted rotor blades is presented. The focus is on the flow in the near tip region of the blade-to-blade passage of the rotor. The flow has been modelled experimentally in a transonic wind tunnel and numerically by means of 2D and 3D Navier-Stokes equation solvers. The profiles of the rotor cascades are characterized by law turning angles and a high-velocity exit flow. Detailed flow measurements have been carried out and analysed. A comparison has been made between the experimental and numerical results, and is discussed in detail. The design and test data of the flow through the upper sections of the span are presented. The effects of the tip leakage flow are evaluated and the three-dimensional patterns of the main flow are estimated. Other points of interest are the results of 3D Navier-Stokes analysis of the stage flow as compared to 2D simulations and wind tunnel experiments, together with the question of the limitations of the individual methods as they all use approximations to the actual flow in the turbine stage.

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