Investigating pitching moment stall through dynamic wind tunnel test

2019 ◽  
Vol 234 (2) ◽  
pp. 267-279
Author(s):  
Alessandro Pontillo ◽  
Sezsy Yusuf ◽  
Guillermo Lopez ◽  
Dominic Rennie ◽  
Mudassir Lone
Keyword(s):  
Parameter Estimation ◽  
Wind Tunnel ◽  
Wind Tunnel Test ◽  
Angular Acceleration ◽  
Direct Calculation ◽  
Dynamic Stall ◽  
Nonlinear Behaviour ◽  
Wind Tunnel Testing ◽  
Pitching Moment ◽  
Heave Motion

Experimental characterisation of aircraft dynamic stall can be a challenging and complex system identification activity. In this article, the authors present a method that combines dynamic wind tunnel testing with parameter estimation techniques to study the nonlinear pitching moment dynamics of a 1/12 scale Hawk model undergoing moment stall. The instrumentation setup allows direct calculation of angular acceleration terms, such as pitch acceleration, and avoids post-processing steps involving differentiation of signals. Data collected from tests, carried out at 20 m/s and 30 m/s, are used for a brief aerodynamic analysis of the observed stall hysteresis. Then an output-error-based parameter estimation process is used to parameterise dynamic stall models and furthermore, illustrate that in a scenario where the model's heave motion is constrained. The observed nonlinear behaviour arises from the nonlinear angle of attack and linear pitch rate components.

Wind Tunnel Test on a Slowed Mach-Scaled Hingeless Rotor with Lift Compounding

2021 ◽  
Author(s):  
Shashank Maurya ◽  
Xing Wang ◽  
Inderjit Chopra
Keyword(s):  
Wind Tunnel ◽  
Reverse Flow ◽  
Wind Tunnel Test ◽  
Bending Moment ◽  
Flow Region ◽  
Dynamic Stall ◽  
Rolling Moment ◽  
Slowing Down ◽  
Slowed Rotor ◽  
Compressibility Effects

A single main rotor helicopter's maximum forward speed is limited due to the compressibility effects on the advancing side and reverse flow and dynamic stall on the retreating side. Compound helicopters can address these issues with a slowed rotor and lift compounding. There is a scarcity of test data on compound helicopters, and the present research focuses on a systematic wind tunnel test on lift compounding. Slowing down the rotor increases the advance ratio and, hence, the reverse flow region, which does not produce much lift. The lift is augmented with a wing on the retreating side. A hingeless rotor hub helps to balance the rolling moment with lift offset. Wind tunnel tests were carried out on this configuration up to advance ratios of 0.7 at two different wing incidence angles. Rotor performance, controls, blade structural loads, and hub vibratory loads were measured and compared with in-house comprehensive analysis, UMARC. A comparison between different wing incidences at constant total lift provided many insights into the lift compounding. It increased the vehicle efficiency and reduced peak-to-peak lag bending moment and in-plane 4/rev hub vibratory loads. The only trade-off was steady rotor hub loads and rolling moment at the wing root carried by the fuselage.

Flight Characteristics of Flapping Wing Miniature Air Vehicles With “Figure-8” Spherical Motion

2009 ◽  
Author(s):  
Mohamed B. Trabia ◽  
Woosoon Yim ◽  
Zohaib Rehmat ◽  
Jesse Roll
Keyword(s):  
Mathematical Model ◽  
Wind Tunnel ◽  
Experimental Testing ◽  
Flapping Wing ◽  
Dynamic Stall ◽  
Wind Tunnel Testing ◽  
Servo Motor ◽  
Aerodynamic Forces ◽  
Flapping Motion ◽  
Spherical Motion

Hummingbirds and some insects exhibit “Figure-8” flapping motion that allows them to go through a variety of maneuvers including hovering. Understanding the flight characteristics of Figure-8 flapping motion can potentially yield the foundation of flapping wing UAVs that can experience similar maneuverability. In this paper, a mathematical model of the dynamic and aerodynamic forces associated with Figure-8 motion generated by a spherical four bar mechanism is developed. For validation, a FWMAV prototype with the wing attached to a coupler point and driven by a DC servo motor is created for experimental testing. Wind tunnel testing is conducted to determine the coefficients of flight and the effects of dynamic stall. The wing is driven at speeds up to 12.25 Hz with results compared to that of the model. The results indicate good correlation between mathematical model and experimental prototype.

Videogrammetric Techniques for Wind Tunnel Testing and Applications

2014 ◽  
Vol 986-987 ◽  
pp. 1629-1633
Author(s):  
Zheng Yu Zhang ◽  
Xu Hui Huang ◽  
Jiang Yin ◽  
Han Xuan Lai
Keyword(s):  
Wind Tunnel ◽  
Wave Front ◽  
High Speed ◽  
Marked Point ◽  
Wind Tunnel Test ◽  
Wind Tunnels ◽  
Test Model ◽  
Wind Tunnel Testing ◽  
Section Size ◽  
Key Techniques

Videogrammetric measurement is a research focus for the organizations of wind tunnel test because of its no special requirements on the test model, its key techniques for the vibration environment of the high speed wind tunnel are introduced by this paper, such as the solution of exterior parameters with big-angle large overlap, the algorithm of image processing for extracting marked point, the method of camera calibration and wave-front distortion field measurement. The great requirements and application prospects of videogrammetry in wind tunnel fine testing have been demonstrated by several practice experiments, including to measure test model’s angle of attack, dynamic deformations and wave-front distortion field in high speed wind tunnels whose test section size is 2 meters.

Wind Tunnel Testing of Composite Wing Flutter Speed due to Control Surface Excitation

2013 ◽  
Vol 315 ◽  
pp. 359-363 ◽  
Author(s):  
Mahzan Muhammad Iyas ◽  
Muhamad Sallehuddin ◽  
Mat Ali Mohamed Sukri ◽  
Mansor Mohd Shuhaimi
Keyword(s):  
Wind Tunnel ◽  
Dynamic Instability ◽  
Wind Tunnel Test ◽  
Control Surface ◽  
Wind Tunnel Testing ◽  
Structural Stiffness ◽  
Wing Flutter ◽  
Flutter Speed ◽  
Surface Excitation ◽  
Composite Wing

Flutter is a dynamic instability problem represents the interaction among aerodynamic forces and structural stiffness during flight. The study was conducted to investigate whether deflecting the control surface will affect the flutter speed and the flutter frequency. A wind tunnel test was performed using a flat plate wing made of composite material. It was found that by deflecting the control surface at 45°, the wing entered flutter state at wind speed of 28.1 m/s instead of 33.4 m/s. In addition, the flutter frequency also reduced from 224.52 Hz to 198.96 Hz. It was concluded that by deflecting the control surface, the wing experienced flutter at lower speed and frequency.

Videogrammetry of the Model’s Attitude in Wind Tunnel Testing

2012 ◽  
Vol 190-191 ◽  
pp. 1273-1277 ◽  
Author(s):  
Zheng Yu Zhang ◽  
Zhong Xiang Sun ◽  
Xu Hui Huang ◽  
Yan Sun
Keyword(s):  
Standard Deviation ◽  
Wind Tunnel ◽  
Drag Coefficient ◽  
Systematic Error ◽  
Measurement System ◽  
High Speed ◽  
Wind Tunnel Test ◽  
Wind Tunnel Testing ◽  
Supersonic Wind Tunnel ◽  
Tunnel Testing

The advanced precision of drag coefficient is 0.0001 for the high speed wind tunnel test of measuring forces, the model’s angle of attack precision is ≤0.01°following errors distribution. A videogrammetric method of model’s attitude is therefore proposed, its uncertainty is investigated, and a compensation method of its systematic error is also presented by this paper. The three engineering videogrammetric experiments of attack angle in 2 meter supersonic wind tunnel testing have demonstrated that measuring standard deviation of videogrammetric measurement system established by this paper is ≤0.0094°, in addition it neither destroys the model’s shape, nor changes the stiffness or strength, so it is useful and effective.

scholarly journals Wind tunnel testing of additive manufactured aircraft components

2018 ◽  
Vol 24 (5) ◽  
pp. 886-893 ◽  
Author(s):  
Z.W. Teo ◽  
T.H. New ◽  
Shiya Li ◽  
T. Pfeiffer ◽  
B. Nagel ◽  
...  
Keyword(s):  
Additive Manufacturing ◽  
Wind Tunnel ◽  
Wind Tunnel Test ◽  
Cost Effective ◽  
Wind Tunnel Testing ◽  
Content Type ◽  
Wind Tunnel Measurement ◽  
Measurement Results ◽  
Joined Wing ◽  
Tunnel Testing

Purpose This paper aims to report on the physical distortions associated with the use of additive manufactured components for wind tunnel testing and procedures adopted to correct for them. Design/methodology/approach Wings of a joined-wing test aircraft configuration were fabricated with additive manufacturing and tested in a subsonic closed-loop wind tunnel. Wing deflections were observed during testing and quantified using image-processing procedures. These quantified deflections were then incorporated into numerical simulations and results had agreed with wind tunnel measurement results. Findings Additive manufacturing provides cost-effective wing components for wind tunnel test components with fast turn-around time. They can be used with confidence if the wing deflections could be accounted for systematically and accurately, especially at the region of aerodynamic stall. Research limitations/implications Significant wing flutter and unsteady deflections were encountered at higher test velocities and pitch angles. This reduced the accuracy in which the wing deflections could be corrected. Additionally, wing twists could not be quantified as effectively because of camera perspectives. Originality/value This paper shows that additive manufacturing can be used to fabricate aircraft test components with satisfactory strength and quantifiable deflections for wind tunnel testing, especially when the designs are significantly complex and thin.

A Three-Component, Strain-Gauged Sting Balance for Use in Small Low-Speed Wind Tunnels

1966 ◽  
Vol 70 (670) ◽  
pp. 951-952 ◽  
Author(s):  
J. A. C. Marsden
Keyword(s):  
Wind Tunnel ◽  
The Other ◽  
Wind Tunnels ◽  
List Type ◽  
Wind Tunnel Testing ◽  
Pitching Moment ◽  
Type Number ◽  
Aerodynamic Loads ◽  
Component Strain ◽  
Manufacturing Time

In preparation for the wind tunnel testing of a series of aerodynamic research models a strain-gauged balance was sought which could be successfully made without the use of sophisticated tools. The principal requirements which influenced the design of the balance were:(a)It must enable lift, drag and pitching moment to be measured.(b)Deformation of the balance under the aerodynamic loads to be small.(c)Use of only basic workshop tools.(d)Short manufacturing time.Further, the models were to be sting mounted at one end of the balance with their span vertical. The other end of the balance was to be rigidly fixed to a supporting stand which would be mounted on the wind tunnel turntable to permit incidence variation (Fig. 5).

scholarly journals Dynamic Stall Model for Tower Shadow Effects on Downwind Turbines and Its Scale Effects

Energies ◽  
2020 ◽  
Vol 13 (19) ◽  
pp. 5237
Author(s):  
Shigeo Yoshida
Keyword(s):  
Wind Speed ◽  
Wind Tunnel ◽  
Scale Effects ◽  
Wind Tunnel Test ◽  
Dynamic Stall ◽  
Test Model ◽  
Wind Speed Profile ◽  
Empirical Parameter ◽  
Wake Model ◽  
Tower Shadow

A dynamic stall model for tower shadow effects is developed for downwind turbines. Although Munduate’s model shows good agreement with a 1.0 m wind tunnel test model, two problems exist: (1) it does not express load increase before the entrance of the tower wake, and (2) it uses the empirical tower wake model to determine the wind speed profile behind the tower. The present research solves these problems by combining Moriarty’s tower wake model and the entrance condition of the tower wake. Moriarty’s model does not require any empirical parameter other than tower drag coefficient and it expresses positive wind speed around the tower also. Positive wind speed change is also allowed as the tower wake entrance condition in addition to the negative change observed in the previous model. It demonstrates better agreement with a wind tunnel test and contributes to the accuracy of the fatigue load, as it expresses a slight increase in load around the entrance of the tower wake. Furthermore, the scale effects are also evaluated; lift deviation becomes smaller as the scale increases, i.e., lower rotor speed.

Sign in / Sign up

Export Citation Format

Share Document