The Assessment of Results obtained in Transonic Wind Tunnels

1958 ◽  
Vol 62 (565) ◽  
pp. 21-26
Author(s):  
F. O'hara
Keyword(s):  
Aerodynamic Characteristics ◽  
Comparative Assessment ◽  
Wind Tunnels ◽  
Pressure Measurements ◽  
Interference Effects ◽  
Flow Conditions ◽  
Free Flight ◽  
Flow Uniformity ◽  
General Reliability ◽  
Flight Model

The development of wind tunnel sections with partly open walls has made it possible to operate at continuously variable speeds through the transonic range up to low supersonic speeds. Some consideration must be given, however, to the general reliability of the measurements in these tunnels of the aerodynamic characteristics of air vehicles or missiles. A comparative assessment of the possible overall errors in force and pressure measurements in relation to desirable standards of accuracy is, in fact, required. A number of points connected with such an assessment are briefly discussed (mainly on the basis of experience in the 3 ft. tunnel at R.A.E., Bedford) in this paper, which touches on flow uniformity, accuracy of model manufacture, and interference effects, including a comparison between tunnel and free flight model results; illustrative examples of results for an aircraft model, with some full scale flight comparisons, are discussed briefly and a few comments are made on the problems associated with the achievement of representative flow conditions on sting–mounted models at transonic speeds.

Validation of Sub-millimeter Resolution Pressure Measurement on Free Flight Model Mach 1.5

2021 ◽  
Author(s):  
Joseph Gonzales ◽  
Daiki Kurihara ◽  
Hiroki Nagai ◽  
Hirotaka Sakaue ◽  
Aleksandar Jemcov
Keyword(s):  
Pressure Measurement ◽  
Free Flight ◽  
Flight Model

scholarly journals Comparative Assessment of Tubular Ceramic, Spiral Wound, and Hollow Fiber Membrane Microfiltration Module Systems for Milk Protein Fractionation

Foods ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 692
Author(s):  
Roland Schopf ◽  
Florian Schmidt ◽  
Johanna Linner ◽  
Ulrich Kulozik
Keyword(s):  
Hollow Fiber ◽  
Milk Protein ◽  
Hollow Fiber Membrane ◽  
Comparative Assessment ◽  
Transmission Factor ◽  
Transmembrane Pressure ◽  
Protein Fractionation ◽  
Flow Conditions ◽  
Local Pressure ◽  
Spiral Wound

The fractionation efficiency of hollow fiber membranes (HFM) for milk protein fractionation was compared to ceramic tubular membranes (CTM) and spiral wound membranes (SWM). HFM combine the features of high membrane packing density of SWM and the more defined flow conditions and better control of membrane fouling in the open flow channel cross-sections of CTM. The aim was to comparatively analyze the effect of variations in local pressure and flow conditions while using single industrially sized standard modules with similar dimensions and module footprints (module diameter and length). The comparative assessment with varied transmembrane pressure was first applied for a constant feed volume flow rate of 20 m3 h−1 and, secondly, with the same axial pressure drop along the modules of 1.3 bar m−1, similar to commonly applied crossflow velocity and wall shear stress conditions at the industrial level. Flux, transmission factor of proteins (whey proteins and serum caseins), and specific protein mass flow per area membrane and per volume of module installed were determined as the evaluation criteria. The casein-to-whey protein ratios were calculated as a measure for protein fractionation effect. Results obtained show that HFM, which so far are under-represented as standard module types in industrial dairy applications, appear to be a competitive alternative to SWM and CTM for milk protein fractionation.

scholarly journals Aerodynamic characteristics of a free-flight scramjet vehicle in shock tunnel

2021 ◽  
Vol 62 (7) ◽  
Author(s):  
Marie Tanno ◽  
Hideyuki Tanno
Keyword(s):  
System Analysis ◽  
Force Measurement ◽  
Prediction Interval ◽  
Angular Acceleration ◽  
Aerodynamic Characteristics ◽  
Measurement Precision ◽  
Shock Tunnel ◽  
Free Flight ◽  
Vehicle Model ◽  
Aerodynamic Test

Abstract A multi-component aerodynamic test for an airframe-engine integrated scramjet vehicle model was conducted in the free-piston shock tunnel HIEST. A free-flight force measurement technique was applied to the scramjet vehicle model named MoDKI. A new method using multiple piezoelectric accelerometers was developed based on overdetermined system analysis. Its unique features are the following: (1) The accelerometer’s mounting location can be more flexible. (2) The measurement precision is predicted to be improved by increasing the number of accelerometers. (3) The angular acceleration can be obtained with single-axis translational accelerometers instead of gyroscopes. (4) Through the averaging process of the multiple accelerometers, model natural vibration is expected to be mitigated. With eight model-onboard single-axis accelerometers, the three-component aerodynamic coefficients (Drag, Lift, and Pitching moment) of MoDKI were successfully measured at the angle of attack from 0.7 to 3.4 degrees under a Mach 8 free-stream test flow condition. A linear regression fitting revealed a 95% prediction interval as the measurement precision of each aerodynamic coefficient. Graphical abstract

Computational Study of the Risø-B1-18 Airfoil with a Hinged Flap Providing Variable Trailing Edge Geometry

2005 ◽  
Vol 29 (2) ◽  
pp. 89-113 ◽  
Author(s):  
Niels Troldborg
Keyword(s):  
Reynolds Number ◽  
Unsteady Flow ◽  
Computational Study ◽  
Turbine Blades ◽  
Aerodynamic Characteristics ◽  
Flow Conditions ◽  
Wind Turbine Blades ◽  
Trailing Edge ◽  
Edge Geometry ◽  
Fully Developed Turbulent Flow

A comprehensive computational study, in both steady and unsteady flow conditions, has been carried out to investigate the aerodynamic characteristics of the Risø-B1-18 airfoil equipped with variable trailing edge geometry as produced by a hinged flap. The function of such flaps should be to decrease fatigue-inducing oscillations on the blades. The computations were conducted using a 2D incompressible RANS solver with a k-w turbulence model under the assumption of a fully developed turbulent flow. The investigations were conducted at a Reynolds number of Re = 1.6 · 106. Calculations conducted on the baseline airfoil showed excellent agreement with measurements on the same airfoil with the same specified conditions. Furthermore, a more widespread comparison with an advanced potential theory code is presented. The influence of various key parameters, such as flap shape, flap size and oscillating frequencies, was investigated so that an optimum design can be suggested for application with wind turbine blades. It is concluded that a moderately curved flap with flap chord to airfoil curve ratio between 0.05 and 0.10 would be an optimum choice.

Calculation of tunnel wall interference from wall-pressure measurements

1988 ◽  
Vol 92 (911) ◽  
pp. 36-53 ◽  
Author(s):  
P. R. Ashill ◽  
R. F. A. Keating
Keyword(s):  
Experimental Evaluation ◽  
Solid Wall ◽  
Wall Pressure ◽  
Wind Tunnels ◽  
Pressure Measurements ◽  
Complex Flows ◽  
Tunnel Wall ◽  
Model Flow ◽  
Good Agreement

Summary A method is described for calculating wall interference in solid-wall wind tunnels from measurements of static pressures at the walls. Since it does not require a simulation of the model flow, the technique is particularly suited to determining wall interference for complex flows such as those over VSTOL aircraft, helicopters and bluff shapes (e.g. cars and trucks). An experimental evaluation shows that the method gives wall-induced velocities which are in good agreement with those of existing methods in cases where these techniques are valid, and illustrates its effectiveness for inclined jets which are not readily modelled.

scholarly journals Modeling the processes of aerogasdynamics of structural elements of a supersonic aircraft

2019 ◽  
Author(s):  
E.S. Studennikov
Keyword(s):  
Stress Transfer ◽  
Aerodynamic Characteristics ◽  
Wind Tunnels ◽  
Transfer Model ◽  
Structural Elements ◽  
Base Region ◽  
Supersonic Aircraft ◽  
Wide Range ◽  
Sharp Cone ◽  
Semi Empirical

The purpose of the research was to study the aerodynamic features of the flow around the simplest structural elements of an aircraft, such as sharp and blunt-nose cones. For calculations we applied the perfect gas model. To describe flows with large adverse pressure gradients, we used the Menter's shear stress transfer model. We analyzed changes in the aerodynamic characteristics of the cones in a wide range of angles of attack α and flow Mach M∞ numbers. Furthermore, we investigated the parameters of the base region of the sharp cone at transonic and supersonic speeds, and compared the simulation results with the data of a physical experiment both in wind tunnels and on a ballistic installation. The comparison showed good agreement with the experimental data. Numerical simulation data can be applied to form the external appearance of aircraft for various purposes, to study the influence of the temperature factor on the flow around bodies, and to create semi-empirical models for calculating the parameters of the base region of conical bodies.

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