Supersonic Wind Tunnel Experiment on Aerodynamic Characteristics and Winglets Effects of the Tapered Supersonic Biplane

2011 ◽  
Author(s):  
Takashi Fujisono ◽  
Hiroshi Yamashita ◽  
Atsushi Toyoda ◽  
Hiroki Nagai ◽  
Keisuke Asai ◽  
...  
Keyword(s):  
Wind Tunnel ◽  
High Speed ◽  
Type A ◽  
Aerodynamic Characteristics ◽  
Type B ◽  
Supersonic Wind Tunnel ◽  
Wing Model ◽  
Mach Numbers ◽  
The Difference ◽  
Wing Tip

The aerodynamic characteristics and the effects of tip plates of a tapered supersonic biplane wing during the starting process have been investigated through Experimental and Computational Fluid Dynamics (EFD/CFD). Three types of the wing model were used: without tip plate (type-N); with the tip plate which covers only the aft-half of the wing tip (type-A); with the tip plate which covers the entire wing tip (type-B). Experiment was conducted in the supersonic blowdown wind tunnel with 600 mm × 600 mm cross section located at the High-speed Wind Tunnel Facility of Institute of Space and Astronautical Science (ISAS/JAXA). The flow conditions covered from M∞ = 1.5 to 1.9 with increments of 0.1. Pressure-Sensitive Paint was applied to measure pressure distributions on the surface of the wing. CFD simulations were conducted to compare with experiments and to investigate effects of the Mach numbers in detail. The tapered biplane wing without the tip plate was found to start between M∞ = 1.8 and 1.9. The difference of the starting Mach numbers between type-N and type-A was small. On the other hand, the starting Mach number of type-B was about 0.05 higher than that of type-N.

scholarly journals Convergence of transonic wind tunnel test results of the AGARD-B standard model

2020 ◽  
Vol 48 (4) ◽  
pp. 761-769
Author(s):  
Dijana Damljanović ◽  
Đorđe Vuković ◽  
Goran Ocokoljić ◽  
Boško Rašuo
Keyword(s):  
Wind Tunnel ◽  
Wind Tunnel Test ◽  
Aerodynamic Characteristics ◽  
Test Results ◽  
Aerodynamic Coefficients ◽  
Supersonic Wind Tunnel ◽  
Mean Values ◽  
Wide Range ◽  
Production Technologies ◽  
Mach Numbers

AGARD-B is a widely-used configuration of a standard wind tunnel model. Beside its originally intended application for correlation of data from supersonic wind tunnel facilities, it was tested in a wide range of Mach numbers and, more recently, used for assessment of wall interference effects, validation of computational fluid dynamics codes and validation of new model production technologies. The researchers and wind tunnel test engineers would, naturally, like to know the "true" aerodynamic characteristics of this model, for comparison with their own work. Obviously, such data do not exist, but an estimate can be made of the dispersion of test results from various sources and of the probable "mean" values of the aerodynamic coefficients. To this end, comparable transonic test results for the AGARD-B model at Mach numbers 0.77, Mach 1.0 and Mach 1.17 from six wind tunnels were analyzed and average values and dispersions of the aerodynamic coefficients were computed.

Multi-Angular Flame Measurements and Analysis in a Supersonic Wind Tunnel Using Fiber Based Endoscopes

2015 ◽  
Author(s):  
Lin Ma ◽  
Andrew J. Wickersham ◽  
Wenjiang Xu ◽  
Scott J. Peltier ◽  
Timothy M. Ombrello ◽  
...  
Keyword(s):  
Wind Tunnel ◽  
Thermal Management ◽  
High Speed ◽  
Flow Structures ◽  
Data Sets ◽  
Propulsion Systems ◽  
Supersonic Wind Tunnel ◽  
Optical Access ◽  
Equipment Cost ◽  
Pod Analysis

This paper reports new measurements and analysis made in the Research Cell 19 supersonic wind-tunnel facility housed at the Air Force Research Laboratory. The measurements include planar chemiluminescence from multiple angular positions obtained using fiber based endoscopes (FBEs) and the accompanying velocity fields obtained using particle image velocimetry (PIV). The measurements capture the flame dynamics from different angles (e.g., the top and both sides) simultaneously. The analysis of such data by proper orthogonal decomposition (POD) will also be reported. Non-intrusive and full-field imaging measurements provide a wealth of information for model validation and design optimization of propulsion systems. However, it is challenging to obtain such measurements due to various implementation difficulties such as optical access, thermal management, and equipment cost. This work therefore explores the application of FBEs for non-intrusive imaging measurements in supersonic propulsion systems. The FBEs used in this work are demonstrated to overcome many of the practical difficulties and significantly facilitate the measurements. The FBEs are bendable and have relatively small footprints (compared to high-speed cameras), which facilitates line-of-sight optical access. Also, the FBEs can tolerate higher temperatures than high-speed cameras, ameliorating the thermal management issues. Lastly, the FBEs, after customization, can enable the capture of multiple images (e.g., images of the flowfields at multi-angles) onto the same camera chip, greatly reducing the equipment cost of the measurements. The multi-angle data sets, enabled by the FBEs as discussed above, were analyzed by POD to extract the dominating flame modes when examined from various angular positions. Similar analysis was performed on the accompanying PIV data to examine the corresponding modes of the flowfields. The POD analysis provides a quantitative measure of the dominating spatial modes of the flame and flow structures and is an effective mathematical tool to extract key physics from large data sets such as the high-speed measurements collected in this study. However, past POD analysis has been limited to data obtained from one orientation only. The availability of data at multiple angles in this study is expected to provide further insights into the flame and flow structures in high-speed propulsion systems.

scholarly journals Aerodynamic Analysis of a Flapping Wing Aircraft for Short Landing

2020 ◽  
Vol 10 (10) ◽  
pp. 3404
Author(s):  
Bing Ji ◽  
Zenggang Zhu ◽  
Shijun Guo ◽  
Si Chen ◽  
Qiaolin Zhu ◽  
...  
Keyword(s):  
Aerodynamic Characteristics ◽  
Flapping Wing ◽  
Aerodynamic Analysis ◽  
Drag Forces ◽  
Wing Model ◽  
Aerodynamic Model ◽  
Computational Fluid Dynamics Cfd ◽  
The Difference ◽  
Cfd Method ◽  
Lift And Drag

An investigation into the aerodynamic characteristics has been presented for a bio-inspired flapping wing aircraft. Firstly, a mechanism has been developed to transform the usual rotation powered by a motor to a combined flapping and pitching motion of the flapping wing. Secondly, an experimental model of the flapping wing aircraft has been built and tested to measure the motion and aerodynamic forces produced by the flapping wing. Thirdly, aerodynamic analysis is carried out based on the measured motion of the flapping wing model using an unsteady aerodynamic model (UAM) and validated by a computational fluid dynamics (CFD) method. The difference of the average lift force between the UAM and CFD method is 1.3%, and the difference between the UAM and experimental results is 18%. In addition, a parametric study is carried out by employing the UAM method to analyze the effect of variations of the pitching angle on the aerodynamic lift and drag forces. According to the study, the pitching amplitude for maximum lift is in the range of 60°~70° as the flight velocity decreases from 5 m/s to 1 m/s during landing.

Experimental Studies on Aerodynamic Characteristics of Pantograph System According to the Pantograph Cover Configurations for High Speed Train

2011 ◽  
Author(s):  
Yeongbin Lee ◽  
Minho Kwak ◽  
Kyu Hong Kim ◽  
Dong-Ho Lee
Keyword(s):  
Wind Tunnel ◽  
High Speed ◽  
Aerodynamic Drag ◽  
Aerodynamic Force ◽  
Experimental Studies ◽  
Wind Tunnel Test ◽  
Aerodynamic Characteristics ◽  
Experimental Models ◽  
High Speed Train ◽  
Drag And Lift

In this study, the aerodynamic characteristics of pantograph system according to the pantograph cover configurations for high speed train were investigated by wind tunnel test. Wind tunnel tests were conducted in the velocity range of 20∼70m/s with scaled experimental pantograph models. The experimental models were 1/4 scaled simplified pantograph system which consists of a double upper arm and a single lower arm with a square cylinder shaped panhead. The experimental model of the pantograph cover is also 1/4 scaled and were made as 4 different configurations. It is laid on the ground plate which modeled on the real roof shape of the Korean high speed train. Using a load cell, the aerodynamic force such as a lift and a drag which were acting on pantograph system were measured and the aerodynamic effects according to the various configurations of pantograph covers were investigated. In addition, the total pressure distributions of the wake regions behind the panhead of the pantograph system were measured to investigate the variations of flow pattern. From the experimental test results, we checked that the flow patterns and the aerodynamic characteristics around the pantograph systems are varied as the pantograph cover configurations. In addition, it is also found that pantograph cover induced to decrease the aerodynamic drag and lift forces. Finally, we proposed the aerodynamic improvement of pantograph cover and pantograph system for high speed train.

scholarly journals Numerical method for an assessment of steady and motion-excited flowfields in a transonic cascade wind tunnel

2017 ◽  
Vol 1 ◽  
pp. QL9XVI ◽  
Author(s):  
Atsushi Tateishi ◽  
Toshinori Watanabe ◽  
Takehiro Himeno ◽  
Seiji Uzawa
Keyword(s):  
Wind Tunnel ◽  
Flow Field ◽  
Numerical Method ◽  
Aerodynamic Characteristics ◽  
Pressure Amplitude ◽  
Tunnel Wall ◽  
Flow Simulations ◽  
Influence Coefficients ◽  
The Difference ◽  
Transonic Cascade

AbstractThis article presents a numerical method and its application for an assessment of the flow field inside a wind tunnel. A structured computational fluid dynamics (CFDs) solver with overset mesh technique is developed in order to simulate geometrically complex configurations. Applying the developed solver, a whole transonic cascade wind tunnel is modeled and simulated by a two-dimensional manner. The upstream and downstream periodicity of the cascade and the effect of the tunnel wall on the unsteady flow field are focused on. From the steady flow simulations, the existence of an optimum throttle position for the best periodicity for each tailboard angle is shown, which provides appropriate aerodynamic characteristics of ideal cascades in the wind tunnel environment. Unsteady simulations with blade oscillation is also conducted, and the difference in the influence coefficients between ideal and wind tunnel configurations becomes large when the pressure amplitude increases on the lower blades.

Low-Turbulence High-Speed Wind Tunnel for the Determination of Cascade Shock Losses

1979 ◽  
Author(s):  
J. A. Slovisky ◽  
W. B. Roberts ◽  
D. M. Sandercock
Keyword(s):  
Wind Tunnel ◽  
High Speed ◽  
Axial Compressor ◽  
Pressure Probe ◽  
Supersonic Wind Tunnel ◽  
Smoke Flow ◽  
Contraction Ratio ◽  
Curved Shock Waves ◽  
Visualization Techniques

A low turbulence high-speed wind tunnel, using anti-turbulence screening and a 100:1 contraction ratio, has been found suitable for high-speed smoke flow visualization. The location and strength of normal, oblique, and curved shock waves generated by transonic or supersonic wind tunnel flow over airfoils or through axial compressor cascades is determined by combined shadowgraph and smokelines visualization techniques without the interference effects caused by intrusive probes. The Reynolds number based on chord varied between 50,000 and 106. Preliminary results are compared with the relevant theory and data gathered using a total pressure probe.

An experimental parametric study on planar sheared wings tip devices for low-to-moderate aspect ratio wings

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Lourelay Moreira dos Santos ◽  
Guilherme Ferreira Gomes ◽  
Rogerio F. Coimbra
Keyword(s):  
Wind Tunnel ◽  
Aspect Ratio ◽  
Parametric Study ◽  
Leading Edge ◽  
Aerodynamic Characteristics ◽  
Sweep Angle ◽  
Wind Tunnel Tests ◽  
Content Type ◽  
Wing Tips ◽  
Wing Tip

Purpose The purpose of this study is to investigate the aerodynamic characteristics of a low-to-moderate-aspect-ratio, tapered, untwisted, unswept wing, equipped of sheared wing tips. Design/methodology/approach In this work, wind tunnel tests were made to study the influence in aerodynamic characteristics over a typical low-to-moderate-aspect-ratio wing of a general aviation aircraft, equipped with sheared – swept and tapered planar – wing tips. An experimental parametric study of different wing tips was tested. Variations in its leading and trailing edge sweep angle as well as variations in wing tip taper ratio were considered. Sheared wing tips modify the flow pattern in the outboard region of the wing producing a vortex flow at the wing tip leading edge, enhancing lift at high angles of attack. Findings The induced drag is responsible for nearly 50% of aircraft total drag and can be reduced through modifications to the wing tip. Some wing tip models present complex geometries and many of them present benefits in particular flight conditions. Results have demonstrated that sweeping the wing tip leading edge between 60 and 65 degrees offers an increment in wing aerodynamic efficiency, especially at high lift conditions. However, results have demonstrated that moderate wing tip taper ratio (0.50) has better aerodynamic benefits than highly tapered wing tips (from 0.25 to 0.15), even with little less wing tip leading edge sweep angle (from 57 to 62 degrees). The moderate wing tip taper ratio (0.50) offers more wing area and wing span than the wings with highly tapered wing tips, for the same aspect ratio wing. Originality/value Although many studies have been reported on the aerodynamics of wing tips, most of them presented complex non-planar geometries and were developed for cruise flight in high subsonic regime (low lift coefficient). In this work, an exploration and parametric study through wind tunnel tests were made, to evaluate the influence in aerodynamic characteristics of a low-to-moderate-aspect-ratio, tapered, untwisted, unswept wing, equipped of sheared wing tips (wing tips highly swept and tapered).

Elimination of Ammonium Ion from the a-Hydroxyalkyl Radicals of Serine and Threonine in Aqueous Solution and the Difference in the Reaction Mechanism

1985 ◽  
Vol 40 (11-12) ◽  
pp. 785-797 ◽  
Author(s):  
Günter Behrens ◽  
Günther Koltzenburg
Keyword(s):  
Kinetic Data ◽  
Type A ◽  
Ammonium Ion ◽  
Type B ◽  
Ketyl Radical ◽  
Time Resolved ◽  
Hydroxyalkyl Radical ◽  
The Difference ◽  
Hydroxyalkyl Radicals ◽  
Radical Attack

Abstract The zwitterionic radicals HO-ĊH-CH(COO-)NH3+ (4a) and HO-Ċ(CH3)-CH(COO-)NH3+ (4b) are the main species produced upon OH· radical attack in aqueous solutions at pH 3-7 at the amino acids serine, HO-CH2-CH(COO-)NH3+, or threonine, HO-CH(CH3)-CH(COO-)NH3+, respectively. Both radicals undergo elimination of NH4+ ion to form the radicals O=CH-ĊH-COO- (7) or CH3-CO-ĊH-COO- (9) respectively.The pKa of the serine-derived cationic radical HO-ĊH-CH(COOH)NH3+ (3a) (3a ⇄ 4a + H+), was determined by ESR spectroscopy to 2.2 ± 0.1 at 276 K. From kinetic data the pKa(OH) of radical 4a (4a ⇄ O-ĊH-CH(COO-)NH3+ (5a) + H+) was calculated to 7.0. The elimination of NH3 takes place from the ketyl radical 5a (type-B mechanism), the rate constant was calculated from kinetic data to 2.4 × 106 s-1 at 290 K.The half-lives of radicals 4a and 4b were measured by time-resolved conductivity changes upon pulse radiolysis, 170 ± 10 μs for 4a and 26 ± 2 μs for 4b, at 290 K and pH 5.8 .With the threonine derived radicals elimination of NH3 takes place at the stage of the α-hydroxyalkyl radical 4b (type-A mechanism). In this series the pKa of the product radical CH3-CO-ĊH-COOH (8) (8 ⇄ 9 + H+), was determined by ERS spectroscopy to 2.7 ± 0.1. The reasons for the observed mechanistic differences (type-A versus type-B decay) are discussed. As further examples for a type-B decay some preliminary data on the elimination of HF from the radicals CF3-Ċ(OH)-CF3 and CF3-ĊH-OH have been added.

scholarly journals Test Facility for High-Speed Probe Calibration

2019 ◽  
Vol 213 ◽  
pp. 02033
Author(s):  
Tomáš Jelínek ◽  
Erik Flídr ◽  
Martin Němec ◽  
Jan Šimák
Keyword(s):  
Wind Tunnel ◽  
Flow Field ◽  
Total Pressure ◽  
High Speed ◽  
Test Facility ◽  
Nozzle Outlet ◽  
Wide Range ◽  
Mach Numbers ◽  
Probe Calibration ◽  
Subsonic Nozzle

A new test facility was built up as a part of a closed-loop transonic wind tunnel in VZLU´s High-speed Aerodynamics Department. The wind tunnel is driven by a twelve stage radial compressor and Mach and Reynolds numbers can be changed by the compressor speed and by the total pressure in the wind tunnel loop by a set of vacuum pumps, respectively. The facility consists of an axisymmetric subsonic nozzle with an exit diameter de = 100 mm. The subsonic nozzle is designed for regimes up to M = 1 at the nozzle outlet. At the nozzle inlet there is a set of a honeycomb and screens to ensure the flow stream laminar at the outlet of the nozzle. The subsonic nozzle can be supplemented with a transonic slotted nozzle or a supersonic rigid nozzle for transonic and supersonic outlet Mach numbers. The probe is fixed in a probe manipulator situated downstream of the nozzle and it ensures a set of two perpendicular angles in a wide range (±90°). The outlet flow field was measured through in several axial distances downstream the subsonic nozzle outlet. The total pressure and static pressure was measured in the centreline and the total pressure distribution in the vertical and horizontal plane was measured as well. Total pressure fluctuations in the nozzle centreline were detected by a FRAP probe. From the initial flow measurement in a wide range of Mach numbers the best location for probe calibration was chosen. The flow field was found to be suitable for probe calibration.

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