scholarly journals Design and analysis of smoke flow visualization apparatus for wind tunnel

2021 ◽  
Vol 1206 (1) ◽  
pp. 012014
Author(s):  
D Raval ◽  
S V Jain ◽  
A M Acharii ◽  
K Ghosh
Keyword(s):  
Wind Tunnel ◽  
Flow Visualization ◽  
Operating Conditions ◽  
Design Flow ◽  
Column Height ◽  
Stream Velocity ◽  
Variable Frequency Drive ◽  
Power Inputs ◽  
Fan Speed ◽  
Naca 0015

Abstract In the present study, the design and analysis of smoke generator are done for the low-speed wind tunnel. The wind tunnel fan is fitted with the Variable Frequency Drive to produce the wind speed in the range of 3 to 32 m/s with fan speed of 150 to 1500 rpm. The design of smoke generator was done according to Preston Sweeting mist generator principle corresponding to the free stream velocity of 3 m/s. A controlled smoke generator consisting of kerosene reservoir, controlled heater, blower, liquid column height adjustment mechanism, valves etc. was designed and fabricated. The smoke generator produced the smoke at the rate of 154 cm3/s which was close to the design flow rate of 149 cm3/s. To supply the required quantity of smoke in the wind tunnel, the smoke rake of NACA 0010 profile was developed and installed in the rapid contraction section of the wind tunnel to achieve the streamlined flow. The parametric studies were done on the smoke generator at different power inputs and its effects were studied on smoke temperature, smoke discharge and boiling time of the kerosene. The flow visualization was carried out on NACA 0015 airfoil model and the images were captured to examine the flow physics around them under different operating conditions.

The Effect of Pitch Location on Dynamic Stall

1989 ◽  
Vol 111 (3) ◽  
pp. 256-262 ◽  
Author(s):  
E. J. Jumper ◽  
R. L. Dimmick ◽  
A. J. S. Allaire
Keyword(s):  
Wind Tunnel ◽  
Angle Of Attack ◽  
Dynamic Stall ◽  
Stream Velocity ◽  
Pressure Drag ◽  
Constant Rate ◽  
Theoretical Predictions ◽  
Momentum Integral ◽  
Dimensional Variable ◽  
Naca 0015

This paper reports the results of theoretical and wind-tunnel studies of the effect of pitch location on dynamic stall for an airfoil pitching at constant rate. A modified momentum-integral method was used to predict the effect of pitch location and rate on the delay in quarter-chord separation. The wind-tunnel study involved the collection of time-varying pressure readings from 16 locations on an NACA 0015 airfoil that were subsequently used to determine lift, pressure-drag, and moment coefficients as functions of angle of attack for 140 test cases, covering 28 dynamic airspeed/pitch-rate/pitch-location combinations. Dynamic-stall effects of change (from steady flow) in the angle of attack at which separation occurs at the quarter chord (for comparison with the momentum-integral results), and change in the angle of attack at which stall occurs were extracted from these data and found to collapse best onto a non-dimensional pitch rate given by the chord times the pitch rate divided by two times the free-stream velocity. An adjusted non-dimensional rate formed by replacing one half the chord with the fraction of the chord corresponding to the pitch location was also examined and found not to be the proper non-dimensional variable for collapsing the data. The quarter-chord separation data compared favorably with the theoretical predictions.

Bow-Thruster Jet Flow

1971 ◽  
Vol 15 (03) ◽  
pp. 177-195
Author(s):  
John L. Beveridge
Keyword(s):  
Wind Tunnel ◽  
Flow Visualization ◽  
Potential Flow ◽  
Free Stream ◽  
Stream Velocity ◽  
Ambient Flow ◽  
Pressure Distributions ◽  
Pressure Tests ◽  
Visualization Experiments ◽  
Flow Techniques

Interaction between the ambient flow of a hull and bow-thruster inflow and outflow is examined theoretically and experimentally. Pressure distributions for duct inflow were derived by potential-flow techniques, and wind-tunnel pressure tests and flow-visualization experiments were conducted to determine the characteristics of duct outflow. Generalized and specific results are presented and discussed for two sizes of circular ducts operating over a range of ratios of free-stream velocity to jet velocity.

scholarly journals Experimental Investigation on the Effect of Multi-Winglets

2011 ◽  
pp. 43-46
Author(s):  
Srikanth G, ◽  
Surendra Bogadi
Keyword(s):  
Experimental Study ◽  
Experimental Investigation ◽  
Wind Tunnel ◽  
Flow Visualization ◽  
Flow Speed ◽  
Aircraft Wing ◽  
Induced Drag ◽  
Subsonic Wind Tunnel ◽  
Wingtip Vortex ◽  
Naca 0015

An extensive experimental study is conducted to examine the potentiality of Multi-Winglets (similar to bird tip feathers) for the reduction of Induced Drag, improved CL without increase in span of aircraft wing. The model composed of a rectangular wing built from NACA 0015 airfoil constituted of three winglets, which are small wings without sweep & twist. The test conducted in subsonic wind tunnel at flow speed 20m/s and placing the wing at angle of attack ranging from -5 to +15 deg. And also the wing with no winglet (bare wing) and with single winglet also tested in the same condition as in the case of three winglets (multi-winglet). Wind tunnel balances provided lift measurements and tuft flow visualization obtained wingtip vortex information. The results show that multi-winglet system reduced induced drag by 27.9% and improved CL by 26.5% compare to bare wing.

Supersonic Nonequilibrium Plasma Wind-Tunnel Measurements of Shock Modification and Flow Visualization

AIAA Journal ◽  
10.2514/2.841 ◽  
2000 ◽  
Vol 38 (10) ◽  
pp. 1879-1888 ◽  
Author(s):  
R. Yano ◽  
V. Contini ◽  
E. Plonjes ◽  
P. Palm ◽  
S. Merriman ◽  
...  
Keyword(s):  
Wind Tunnel ◽  
Flow Visualization ◽  
Nonequilibrium Plasma ◽  
Wind Tunnel Measurements

Measured Torsional Vibration Characteristics of a 100 Megawatt Wind Tunnel Drive Line

1999 ◽  
Author(s):  
James M. Corliss ◽  
H. Sprysl
Keyword(s):  
Steady State ◽  
Damping Ratio ◽  
Forced Response ◽  
Operating Conditions ◽  
Pulse Load ◽  
Torsional Vibrations ◽  
Variable Frequency Drive ◽  
Steady State Operation ◽  
Torque Measurements ◽  
Torsional Analysis

Abstract A new 100 MW (135,000 Hp) adjustable speed drive system has recently been installed in the NASA Langley National Transonic Facility. The 100 MW system is the largest of its kind in the world and consists of a salient pole synchronous motor powered by a 12-pulse Load Commutated Inverter variable frequency drive. During system commissioning the drive line torsional vibrations were measured with strain gages and a telemetry-based data acquisition system. The torque measurements included drive start-up and steady-state operation at speeds where the drive motor’s pulsating torques match the drive line’s torsional natural frequency. Rapid drive acceleration rates with short dwell times were effective in reducing torsional vibrations during drive starts. Measured peak torsional vibrations during steady-state operation were comparable to predicted values and large enough to produce noticeable lateral vibrations in the drive line shafting. Cyclic shaft stresses for all operating conditions were well within the fatigue limits of the drive line components. A comparison of the torque measurements to an analytical forced response model concluded that a 0.5% critical damping ratio was appropriately applied in the drive line’s torsional analysis.

Comparison of Wind Tunnel Airfoil Performance Data With Wind Turbine Blade Data

1992 ◽  
Vol 114 (2) ◽  
pp. 119-124 ◽  
Author(s):  
C. P. Butterfield ◽  
George Scott ◽  
Walt Musial
Keyword(s):  
Wind Tunnel ◽  
Wind Turbine ◽  
Peak Power ◽  
Unsteady Aerodynamics ◽  
Leading Edge ◽  
Operating Conditions ◽  
Performance Data ◽  
Horizontal Axis Wind Turbine ◽  
Force Coefficients ◽  
Basic Fluid

Horizontal axis wind turbine (HAWT) performance is usually predicted by using wind tunnel airfoil performance data in a blade element momentum theory analysis. This analysis assumes that the rotating blade airfoils will perform as they do in the wind tunnel. However, when stall-regulated HAWT performance is measured in full-scale operation, it is common to find that peak power levels are significantly greater than those predicted. Pitch-controlled rotors experience predictable peak power levels because they do not rely on stall to regulate peak power. This has led to empirical corrections to the stall predictions. Viterna and Corrigan (1981) proposed the most popular version of this correction. But very little insight has been gained into the basic cause of this discrepancy. The National Renewable Energy Laboratory (NREL), funded by the DOE, has conducted the first phase of an experiment which is focused on understanding the basic fluid mechanics of HAWT aerodynamics. Results to date have shown that unsteady aerodynamics exist during all operating conditions and dynamic stall can exist for high yaw angle operation. Stall hysteresis occurs for even small yaw angles and delayed stall is a very persistent reality in all operating conditions. Delayed stall is indicated by a leading edge suction peak which remains attached through angles of attack (AOA) up to 30 degrees. Wind tunnel results show this peak separating from the leading edge at 18 deg AOA. The effect of this anomaly is to raise normal force coefficients and tangent force coefficients for high AOA. Increased tangent forces will directly affect HAWT performance in high wind speed operation. This report describes pressure distribution data resulting from both wind tunnel and HAWT tests. A method of bins is used to average the HAWT data which is compared to the wind tunnel data. The analysis technique and the test set-up for each test are described.

Accelerated flow past a symmetric aerofoil: experiments and computations

2007 ◽  
Vol 591 ◽  
pp. 255-288 ◽  
Author(s):  
T. K. SENGUPTA ◽  
T. T. LIM ◽  
SHARANAPPA V. SAJJAN ◽  
S. GANESH ◽  
J. SORIA
Keyword(s):  
Reynolds Number ◽  
Flow Field ◽  
Angle Of Attack ◽  
Stream Velocity ◽  
Published Data ◽  
Navier Stokes Equation ◽  
Moment Coefficient ◽  
Flow Past ◽  
Naca 0015 ◽  
Accelerated Flow

Accelerated flow past a NACA 0015 aerofoil is investigated experimentally and computationally for Reynolds number Re = 7968 at an angle of attack α = 30°. Experiments are conducted in a specially designed piston-driven water tunnel capable of producing free-stream velocity with different ramp-type accelerations, and the DPIV technique is used to measure the resulting flow field past the aerofoil. Computations are also performed for other published data on flow past an NACA 0015 aerofoil in the range 5200 ≤ Re ≤ 35000, at different angles of attack. One of the motivations is to see if the salient features of the flow captured experimentally can be reproduced numerically. These computations to solve the incompressible Navier–Stokes equation are performed using high-accuracy compact schemes. Load and moment coefficient variations with time are obtained by solving the Poisson equation for the total pressure in the flow field. Results have also been analysed using the proper orthogonal decomposition technique to understand better the evolving vorticity field and its dependence on Reynolds number and angle of attack. An energy-based stability analysis is performed to understand unsteady flow separation.

scholarly journals Design and installation of vibration testing system for spring mounted model of wing

2015 ◽  
Vol 18 (4) ◽  
pp. 179-187
Author(s):  
Anh Tien Tran ◽  
Nam Ngoc Linh Hoang
Keyword(s):  
Wind Speed ◽  
Wind Tunnel ◽  
Theoretical Analysis ◽  
Testing System ◽  
Vibration System ◽  
Ultrasonic Sensors ◽  
Wing Model ◽  
Suitable Area ◽  
Naca 0015 ◽  
Theoretical Dynamics

This paper presents the design and installation of measuring vibration system in wind tunnel area 1m x 1m. The theoretical analysis of the spring structure in this model help we possible to design a system for wind tunnel by yourself with suitable area, wind speed as well as survey wing model to obtain results desire. This system helps us to observe the oscillation of wing survey by eyes, but to know exactly how wing fluctuates, also the pitching angle of wing, we use ultrasonic sensors to measure the distance variation, will be presented in more detail in the text. At the same time, the article also shows how to make a simple and durable wing model with NACA 0015 airfoil - wing model will be surveyed ranged in system above. The aerodynamic phenomena affect to the vibration of the wing are also mentioned and overcome in the design of the wing. Finally we process the data after measured to see the similarities between the experiment and the theoretical dynamics of aviation.

scholarly journals 2D Numerical Simulation Study of Airfoil Performance

2021 ◽  
Author(s):  
Nasser Shelil
Keyword(s):  
Experimental Data ◽  
Wind Tunnel ◽  
Air Temperature ◽  
Wind Turbines ◽  
Aerodynamic Force ◽  
Angle Of Attack ◽  
Turbulence Models ◽  
Aerodynamic Characteristics ◽  
Operating Conditions ◽  
Ansys Fluent

Abstract. The aerodynamic characteristics of DTU-LN221 airfoil is studied. ANSYS Fluent is used to simulate the airfoil performance with seven different turbulence models. The simulation results for the airfoil with different turbulence models are compared with the wind tunnel experimental data performed under the same operating conditions. It is found that there is a good agreement between the computational fluid dynamics (CFD) predicted aerodynamic force coefficients with wind tunnel experimental data especially with angle of attack between −5° to 10°. RSM is chosen to investigate the flow field structure and the surface pressure coefficients under different angle of attack between −5° to 10°. Also the effect of changing air temperature, velocity and turbulence intensity on lift and drag coefficients/forces are examined. The results show that it is recommended to operate the wind turbines airfoil at low air temperature and high velocity to enhance the performance of the wind turbines.

Application of Blow-off Wind Tunnel Control Based on Genetic Algorithm Optimized BP-Neural Network PID Neural Network

2013 ◽  
Vol 310 ◽  
pp. 557-559 ◽  
Author(s):  
Li Ji ◽  
Xiao Fei Lian
Keyword(s):  
Neural Network ◽  
Genetic Algorithm ◽  
Wind Tunnel ◽  
Bp Neural Network ◽  
Control Method ◽  
Network Control ◽  
Operating Conditions ◽  
Algorithm Optimization ◽  
Large Delay ◽  
Neural Network Pid

For a blow-off tunnel running, there is the large delay and lag issues. We build a mathematical model of the wind tunnel Mach number control by the test modeling method, then analyse the pros and cons of various control methods based on BP neural network control algorithm. Put forward genetic algorithm optimization neural network adaptive control method to solve the large inertia of the wind tunnel system, and large delay. A large number of simulation studies, run a variety of operating conditions for the wind tunnel simulation proved that the improved adaptive neural network PID control method is reasonable and effective.

Sign in / Sign up

Export Citation Format

Share Document