Effects of Sensor Shape on Oscillating Pressure Measurements With Wind-Tunnel Test Confirmation

2006 ◽  
Author(s):  
David W. Wu ◽  
Hwang Choe
Keyword(s):  
Wind Tunnel ◽  
Pressure Sensor ◽  
Pressure Wave ◽  
Dynamic Pressure ◽  
Three Dimensional ◽  
Wind Tunnel Test ◽  
Flow Patterns ◽  
External Flow ◽  
Pressure Measurements ◽  
Significant Correction

This paper summarizes the effects of the pressure sensor shape on the dynamic oscillating pressure measurements when the pressure wave modulating along the steam/air flow path is to be characterized. In the study presented in the paper, a three-dimensional CFD model of the external flow around the protruding, dome-shaped sensor was developed to evaluate the effects of the sensor shape on the external flow pattern, and the detailed flow patterns were studied with this protruding, dome-shaped sensors and compared with the flow patterns for the flush mounted sensors. Then, a one-dimensional analysis was done to predict that the dynamic pressures measured with the protruding sensor do not require significant correction, and this was later supported by wind tunnel tests. The amplitude of the dynamic pressure measured on the protruding sensor was determined to be ranging from 0 to 8% higher than measured by a flush mounted pressure sensor. The frequency of the pressure wave is not affected by the presence of the protrusion.

Homogeneous, Isotropic Flow in Grid Generated Turbulence

1999 ◽  
Vol 122 (1) ◽  
pp. 51-56 ◽  
Author(s):  
Riccardo Tresso ◽  
David R. Munoz
Keyword(s):  
Wind Tunnel ◽  
Three Dimensional ◽  
Wind Tunnel Test ◽  
Flow Region ◽  
Hot Wire ◽  
Spatial Homogeneity ◽  
One Dimensional ◽  
Streamwise Location ◽  
Dimensional Measurements ◽  
Approach Zero

Detailed grid generated turbulent analysis has been completed using a three-dimensional hot-wire anemometer and traversing mechanism to identify a homogeneous, isotropic flow region downstream of a square mesh. The three-dimensional fluctuating velocity measurements were recorded along the centerline of a wind tunnel test section and spatially over the entire wind tunnel cross section downstream of the square mesh. Turbulent intensities for various grid sizes and Reynolds numbers ranged from a minimum of 0.2 percent to a maximum of 2.2 percent in each of the three principal velocity directions. Spatial homogeneity and isotropy were determined for several turbulent flow conditions and downstream positions using the method of covariances. Covariances, in theory, should approach zero asymptotically; however, in practice, this was not achievable. A subjective judgment is required to determine downstream location where the variance of the three covariances reaches a value close to zero. The average standard deviation provides an estimate for defining the limit or subjective threshold needed to determine the onset of homogeneous, isotropic flow. Implementing this threshold, a quantitative method was developed for predicting the streamwise location for the onset of the homogeneous, isotropic flow region downstream of a 25.4 mm square grid as a function of Reynolds number. A comparison of skewness, determined from one-dimensional hot wire anemometer measurements, and covariances, determined from three dimensional hot wire anemometer measurements, indicates a need for caution when relying solely on one-dimensional measurements for determination of turbulence isotropy. The comprehensive three-dimensional characterization also provides an improved understanding of spatial distribution of fundamental turbulence quantities generated by the grid within a low-speed wind tunnel. [S0098-2202(00)02501-3]

Wind tunnel unsteady pressure measurements using a differential optical fiber Fabry-Perot pressure sensor

2014 ◽  
Author(s):  
Ricardo Correia ◽  
Stephen E. Staines ◽  
Stephen W. James ◽  
Nicholas Lawson ◽  
Kevin Garry ◽  
...  
Keyword(s):  
Wind Tunnel ◽  
Optical Fiber ◽  
Pressure Sensor ◽  
Pressure Measurements ◽  
Unsteady Pressure ◽  
Fabry Perot ◽  
Unsteady Pressure Measurements

A Wind Tunnel Study of Heat Transfer Over Complex Terrain

2003 ◽  
Author(s):  
Michelle Pantoya ◽  
Kenneth Shifflett ◽  
Walter Oler ◽  
William Burton
Keyword(s):  
Boundary Layer ◽  
Wind Tunnel ◽  
Wind Energy ◽  
Flow Behavior ◽  
Three Dimensional ◽  
Flow Patterns ◽  
Atmospheric Conditions ◽  
Unstable Flow ◽  
Scaled Model ◽  
Atmospheric Flow

Maximizing wind energy resources requires a detailed understanding of atmospheric flow behavior over complex topography. The objective of this research is to examine unstable flow behavior over a three-dimensional topographic model, representative of mesa terrain that is common in West Texas. The goal is to develop an understanding of how unstable atmospheric conditions caused by surface heating affect boundary layer flow patterns in the natural environment. This objective was accomplished by experimentally monitoring transient thermal behavior of narrow band liquid crystals over a scaled model. Photographic data was collected as the heated model was subjected to a cooler flow field. The transient isotherms result from cooling as the model is exposed to flow in an atmospheric boundary layer wind tunnel. Results suggest that flow patterns associated with unstable conditions can be explained by increased wind speeds on the lee side of a mesa followed by vigorous mixing causing increased cooling rates around the mesa sides. The results could be used to improve the accuracy of numerical atmospheric flow models, assess the feasibility of developing wind turbine sites, and increase the knowledge-base in order to advance wind energy forecasting techniques.

scholarly journals Simulation and analysis of flow patterns around the scleractinian coral Madracis mirabilis (Duchassaing and Michelotti)

2003 ◽  
Vol 358 (1437) ◽  
pp. 1551-1557 ◽  
Author(s):  
Jaap A. Kaandorp ◽  
Evert A. Koopman ◽  
Peter M. A. Sloot ◽  
Rolf P. M. Bak ◽  
Mark J. A. Vermeij ◽  
...  
Keyword(s):  
Flow Velocity ◽  
Three Dimensional ◽  
Reynolds Numbers ◽  
Flow Patterns ◽  
External Flow ◽  
High Flow ◽  
Low Flow ◽  
Stagnant Region ◽  
Computed Tomography Scanning ◽  
X Ray Computed

Three–dimensional morphologies of Madracis mirabilis were obtained using X–ray computed tomography scanning techniques. The morphologies were used to simulate the flow patterns around the colony. In the simulations, the thin–branching low–flow morph with a relatively larger branch–spacing was compared with the more compact high–flow morph of M. mirabilis . For both morphologies, the inside–colony flow velocities were computed for Reynolds numbers ranging from 154 to 3840. In the high–flow morph, it was found that in the range of investigated Reynolds numbers a stagnant region develops within the colony, whereas in the low–flow morph the stagnant region disappeared. Experiments done under natural conditions suggest that a morph is adapted to a certain external flow velocity and develops a stagnant region below a particular threshold for the external flow velocity. When the external flow velocity exceeds a certain threshold, which is characteristic for the growth form, the core velocity becomes equal to the external velocity. A potential application of a profile of core velocities for a range of Reynolds numbers for a certain morph is the prediction of the optimal external flow velocity for a certain morph, and this can be used to assess the state of the physical (palaeo–) environment.

Conceptual Design of an Adaptive Wind Tunnel for the Generation of Unsteady Complex Flow Patterns

2005 ◽  
Author(s):  
Richard Kirkman ◽  
Meredith Metzger
Keyword(s):  
Wind Tunnel ◽  
Virtual Environments ◽  
Conceptual Design ◽  
Three Dimensional ◽  
Unsteady Aerodynamics ◽  
Mesh Size ◽  
Flow Patterns ◽  
Complex Flow ◽  
Tunnel Design ◽  
Wind Tunnel Design

The present paper describes the conceptual design of a three-dimensional adaptive wind tunnel capable of generating complex, unsteady flow fields in a relatively compact physical domain. The design involves multiple, independently controllable vents located around the periphery of a semi-enclosed facility. Desired flow patterns at target areas within the facility are produced by actively steering the inlet flow via appropriately adjusting the magnitude and direction of the air flow entering from each vent. The present study is motivated by a desire to incorporate tactile wind sensation into CAVE-like virtual environments, thereby increasing the overall sense of immersion in the virtual reality. The present wind tunnel design concept may also have potential application to laboratory studies of such problems as unsteady aerodynamics. Results in the present study include examples of two flow patterns obtained from numerical simulations using Fluent. Results from a companion parametric study analyzing the sensitivity of the numerical solution to mesh size and tolerance are also provided. In addition, the feasibility of using a linear-based control strategy to generate prescribed flow patterns within the wind tunnel is discussed.

Efficient stall compliance prediction method for trimmed very light aircraft with high-lift devices

2016 ◽  
Vol 231 (6) ◽  
pp. 1124-1137
Author(s):  
Nhu Van Nguyen ◽  
Daeyeon Lee ◽  
Maxim Tyan ◽  
Jae-Woo Lee ◽  
Sangho Kim
Keyword(s):  
Wind Tunnel ◽  
Stokes Equations ◽  
Transport Model ◽  
Three Dimensional ◽  
Wind Tunnel Test ◽  
Prediction Method ◽  
Aircraft Design ◽  
Design Stage ◽  
High Fidelity ◽  
Configuration Generation

An efficient stall compliance prediction method using quick configuration generation, adapted mesh, high fidelity analysis, and wind tunnel test data for trimmed very light aircraft is proposed. The three-dimensional Navier–Stokes equations are used to determine the characteristics of the flow field around the aircraft, and the [Formula: see text] shear stress transport model is used to interpret the turbulent flow as a solver in the high fidelity analysis. The calibrated mesh and model are developed by comparing the results with the wind tunnel test and adjusting the adapted mesh to match the wind tunnel data. The calibrated mesh and model are applied to conduct the full-scale very light aircraft analysis for the clean and full flap extended flight conditions to comply with the CS-VLA stall regulations. It is recommended that the flap area be increased in the trimmed full flap extended condition. The proposed method demonstrates the feasibility and effectiveness of very light aircraft VLA stall compliance prediction in reducing the development cost and time with small configuration changes at the preliminary very light aircraft design stage.

scholarly journals Experimental and Numerical Studies on Static Aeroelastic Behaviours of a Forward-Swept Wing Model

2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Yan Ouyang ◽  
Kaichun Zeng ◽  
Xiping Kou ◽  
Yingsong Gu ◽  
Zhichun Yang
Keyword(s):  
Wind Tunnel ◽  
Dynamic Pressure ◽  
Wind Tunnel Test ◽  
Swept Wing ◽  
Lattice Method ◽  
Model Calculations ◽  
Wind Tunnel Tests ◽  
Model Based ◽  
Wing Model ◽  
Fidelity Model

The static aeroelastic behaviours of a flat-plate forward-swept wing model in the vicinity of static divergence are investigated by numerical simulations and wind tunnel tests. A medium fidelity model based on the vortex lattice method (VLM) and nonlinear structural analysis is proposed to calculate the displacements of the wing structure with large deformation. Follower forces effect and geometric nonlinearity are considered to calculate the deformation of the wing by finite element method (FEM). In the wind tunnel tests, the divergence dynamic pressure is predicted by the Southwell method, and the static aeroelastic displacement is measured by a photogrammetric method. The results obtained by the medium fidelity model calculations show reasonable agreement with wind tunnel test results. A high fidelity model based on coupled computational fluid dynamics (CFD) and computational structural dynamics (CSD) predicts better results of the wing tip displacement when the freestream dynamic pressure is approaching the divergence dynamic pressure.

scholarly journals Airfoil profile optimization of an air suction equipment with an air duct

2015 ◽  
Vol 19 (4) ◽  
pp. 1217-1222 ◽  
Author(s):  
Li Qiu ◽  
Rui Wang ◽  
Xiao-Dong Chen ◽  
De-Peng Wang
Keyword(s):  
Boundary Layer ◽  
Wind Tunnel ◽  
Critical Angle ◽  
Air Flow ◽  
Operation Mode ◽  
Wind Tunnel Test ◽  
Flow Fields ◽  
External Flow ◽  
Air Speed ◽  
Profile Optimization

On the basis of boundary layer with the airfoil profile, this research attempts to investigate the effect of the angle of spread of the winged air suction equipment on the efficiency of operation. The application of Fluent with the split-middle method under the identical operation mode is expected to optimize the spread angle. The investigated airfoil profile is NACA6413, of which the restrictions on the critical angle of spread suggested in literature will be overcome through the interactions between the internal and external flow fields. As a result, the air speed might increase. The wind tunnel test employed in this research offers the solid evidences to support this hypothesis. The test demonstrates that when the angle of spread is larger than 12?, the effect of accelerating the air flow is still observable. Following the optimization, the air suction effect of the equipment would be optimal when its angle of spread reached 30?.

Pressure Distributions on Sails Investigated Using Three Methods: On-Water Measurements, Wind-Tunnel Measurements, and Computational Fluid Dynamics

2011 ◽  
Author(s):  
Ignazio Maria Viola ◽  
Richard G. J. Flay
Keyword(s):  
Wind Tunnel ◽  
Wind Tunnel Test ◽  
Full Scale ◽  
Navier Stokes ◽  
Pressure Measurements ◽  
Wind Tunnel Tests ◽  
Pressure Distributions ◽  
Unstable Environment ◽  
Full Scale Tests ◽  
Good Agreement

The main results of a two-year project aimed at comparing full-scale tests, wind tunnel tests, and numerical analysis predictions are presented. Pressure measurements were obtained from both full-scale tests and wind-tunnel tests, in upwind and downwind conditions. The upwind wind tunnel test condition was modelled using a Vortex Lattice code, while the downwind wind-tunnel test was modelled using a Navier-Stokes code. The pressures obtained from the three different methods are compared on three horizontal sections of the headsail, mainsail, and asymmetric spinnaker. In general the pressures from the three experiments showed good agreement. In particular, very good agreement was obtained between the numerical computations and the wind tunnel test results. Conversely, the results from the downwind full-scale pressure measurements showed less similarity due to a slightly tightened trim being used for the spinnaker in the on-water tests. Full-scale tests allow the action of unsteadiness due to the wind, wave and yacht movements to affect the results. This unstable environment caused the asymmetric spinnaker to move around, and a tightened trim was required to prevent the spinnaker from collapsing.

Comparison of wind pressure measurements on tower-like structure obtained from full-scale observation, wind tunnel test, and the CFD technology

2002 ◽  
Vol 90 (12-15) ◽  
pp. 1817-1829 ◽  
Author(s):  
Morimasa Watakabe ◽  
Masamiki Ohashi ◽  
Hisashi Okada ◽  
Yasuo Okuda ◽  
Hitomi Kikitsu ◽  
...  
Keyword(s):  
Wind Tunnel ◽  
Wind Tunnel Test ◽  
Full Scale ◽  
Wind Pressure ◽  
Pressure Measurements
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