scholarly journals EFFECT OF THE FLOW FIELD DEFORMATION IN THE WIND TUNNEL ON THE AERODYNAMIC COEFFICIENTS

2015 ◽  
Vol 55 (3) ◽  
pp. 177-186
Author(s):  
Dušan Maturkanič
Keyword(s):  
Wind Tunnel ◽  
Flow Field ◽  
Test Section ◽  
Air Flow ◽  
Wind Tunnels ◽  
Aerodynamic Coefficients ◽  
Wind Tunnel Measurement ◽  
Field Quality ◽  
Entire Flow ◽  
The Creation

The flow field quality has a principal signification at wind tunnel measurement. The creation of the flow field of air by fan leads to the rotation of entire flow field which is, moreover, deformed at the bends of the wind tunnel with close circulation. Despite the wind tunnels are equipped with the devices which eliminate these non-uniformities, in the most of cases, the air flow field has not ideal parameters in the test section. For the evaluation of the measured results of the model in the wind tunnel, the character of flow field deformation is necessary. The following text describes the possible general forms of the flow field nonuniformity and their effect on the aerodynamic coefficients calculation.

The Study of Design and Installation Process for Supersonic Nozzle

2012 ◽  
Vol 569 ◽  
pp. 500-503
Author(s):  
Lian Sheng Wu ◽  
Guang Li Li ◽  
Qi Fu
Keyword(s):  
Numerical Simulation ◽  
Wind Tunnel ◽  
Flow Field ◽  
Test Section ◽  
Supersonic Nozzle ◽  
Simulation Method ◽  
Supersonic Wind Tunnel ◽  
Numerical Simulation Method ◽  
Field Quality ◽  
The Impact

A practical optimal design method of supersonic nozzle is proposed for a supersonic wind tunnel’s design. Design a set of nozzle wall lines with the same nozzle length and different Mach numbers 1.5, 2.0, 2.5. Use numerical simulation method for the verify and analysis of the designed nozzle. Mainly study the impact of the installation gradient between nozzle and test section on flow field quality. This wind tunnel is the subsonic, transonic and supersonic wind tunnel and its test section cross is 0.2 m × 0.2 m .The impact on flow field quality of the test section was studied quantitatively by using the numerical simulation method. The installation gradient index was given. It has some practical value to the construction of supersonic wind tunnel. At present, this study has been applied in construction of the wind tunnel. The gradient of the test section import shall not be greater than 0.5 mm.

Experimental investigation of the effect of nozzle shape and test section perforation on the stationary and non-stationary characteristics of flow field in the large transonic TsAGI T-128 Wind tunnel

2005 ◽  
Vol 109 (1092) ◽  
pp. 75-82 ◽  
Author(s):  
V. I. Biryukov ◽  
S. A. Glazkov ◽  
A. R. Gorbushin ◽  
A. I. Ivanov ◽  
A. V. Semenov
Keyword(s):  
Wind Tunnel ◽  
Flow Field ◽  
Test Section ◽  
Static Pressure ◽  
Pressure Fluctuations ◽  
Flow Characteristics ◽  
Experimental Investigations ◽  
Drive Power ◽  
Static Pressure Distribution ◽  
Nozzle Shape

Abstract The results are presented for a cycle of experimental investigations of flow field characteristics (static pressure distribution, static pressure fluctuations, upwash, boundary-layer parameters) in the perforated test section of the transonic TsAGI T-128 Wind Tunnel. The investigations concern the effect of nozzle shape, wall open-area ratio, Mach and Reynolds numbers on the above-outlined flow characteristics. During the tests, the main Wind-tunnel drive power is measured. Optimal parameters of the nozzle shape and test section perforation are obtained to minimise acoustic perturbations in the test section and their non-uniformity in frequency, static pressure field non-uniformity, nozzle and test section drag and, accordingly, required main Wind-tunnel drive power.

Advanced Flow Control for Supersonic Blowdown Wind Tunnel Using Extended Kalman Filter

2013 ◽  
Author(s):  
Jiaqi Xi ◽  
Qiang Zhang ◽  
Mian Li ◽  
Zhaoguang Wang
Keyword(s):  
Kalman Filter ◽  
Wind Tunnel ◽  
Flow Control ◽  
Extended Kalman Filter ◽  
Control Strategy ◽  
Test Section ◽  
Stagnation Pressure ◽  
Operating Conditions ◽  
Wind Tunnels ◽  
Wide Range

Supersonic wind tunnels provide controlled test environments for aerodynamic research on scaled models. During the experiment, the stagnation pressure in the test section is required to remain constant. Due to the nonlinearity and distributed characteristics of the controlled system, a robust controller with effective flow control algorithms is required, which is then capable of properly working under different operating conditions. In this paper, an Extended Kalman Filter (EKF) based flow control strategy is proposed and implemented in the controller. The control strategy is designed based on the state estimation of a real blowdown wind tunnel, which is carried out under an EKF structure. One of the distinctive advantages of the proposed approach is its adaptability to a wide range of operating conditions for blowdown wind tunnels. Furthermore, it provides a systematic approach to tune the controller parameters to ensure the stability of the controlled air flow. Experiments with different initial conditions and control targets have been conducted to test the applicability and performance of the designed controller. The results demonstrate that the controller and its strategies can effectively control the stagnation pressure in the test section and maintain the target pressure during the stable stage of the blowdown process.

Numerical and experimental investigations on the reduction of wind tunnel wall interference by means of adaptive slots

2001 ◽  
Vol 105 (1052) ◽  
pp. 571-580 ◽  
Author(s):  
O. Meyer ◽  
W. Nitsche ◽  
I. Futterer
Keyword(s):  
Wind Tunnel ◽  
Test Section ◽  
Wind Tunnels ◽  
Experimental Investigations ◽  
Reference Case ◽  
Tunnel Wall ◽  
Promising Alternative ◽  
Model Flow ◽  
Flexible Walls ◽  
Basic Studies

Abstract The flow in many wind tunnel experiments is affected by the presence of test section walls. The resulting interference can be minimised by correcting the measured model pressures, or by influencing the model flow directly with the use of ventilated or adaptive test section walls. The objective behind the latter technique is to guide the flow in the test section to achieve low interference (i.e. free flow) condition at the model. The most successful technique of flexible, adaptive walls is still restricted to small research wind tunnels due to its mechanical complexity. However, a very promising alternative is the use of adaptive slots in the test section walls. This concept combines the method of passive slotted walls, as they are already implemented in many large wind tunnels, and flexible walls. Additionally, this technique presents the opportunity of full 3D adaptations because the slots can be situated in all four test section walls. This paper presents preliminary experimental results and the latest numerical calculations on the effectiveness of adaptive slots. The experiments were conducted under high subsonic flow conditions in the new slotted test section of the transonic wind tunnel at TU Berlin’s Aeronautical Institute (ILR). The numerical results presented are focussed on the 2D slot adaptation of a 2D-model (CAST7 aerofoil) and the 3D slot adaptation of a body of revolution (3D-ETB). In addition, basic studies were made of the flows associated with a single slot on one wall and a bump on the other. The numerical and the first experimental investigations have shown the potential of adaptive slots to reduce wall interferences effectively. The adaptation accuracy of the investigated slot configurations deviated not more than 3% from the reference case (2D-wall adaptation).

scholarly journals Wind tunnel for studies of latent heat storage

2018 ◽  
Vol 180 ◽  
pp. 02108 ◽  
Author(s):  
Václav Tesař
Keyword(s):  
Wind Tunnel ◽  
Test Section ◽  
Air Flow ◽  
The Body ◽  
Whole Body ◽  
Latent Heat Storage ◽  
Hot Air ◽  
Cold Room ◽  
Solidification Processes ◽  
Sudden Decrease

When a heated solid body temperature reaches the melting point, temperature stops increasing and remains constant until the whole body is completely molten. The heat input during this melting is spent on freeing the body molecules. This latent heat of melting remains inside the body and may be released when the body is cooled and solidifies. This heat was suggested, already several decades ago, for storing thermal energy. The advantage it offers is avoiding high temperature differences - which otherwise decrease effectiveness of storage (by inevitable heat escape by conduction). Also the mass of the body needed to store a given amount of heat is much smaller. For investigations of the melting and solidification processes a special wind tunnel has been designed and is being built in this study. The tested sample of phase change material, encapsulated in a spherical shell, will be exposed in the tunnel to recirculating hot air flow in a 140 mm x 140 mm test section. Sudden decrease in air flow temperature is made by shifting away the whole closed-circuit part of the tunnel and exposing the test section to flow of cold (room temperature) air.

scholarly journals Design procedure and honeycomb screen implementation to the air transtport department’s subsonic wind tunnel

AEROjournal ◽  
2020 ◽  
Vol 16 (2) ◽  
pp. 3-8
Author(s):  
Michal Hrúz ◽  
◽  
Pavol Pecho ◽  
Martin Bugaj
Keyword(s):  
Wind Tunnel ◽  
Air Flow ◽  
Design Procedure ◽  
Reynold Number ◽  
Air Transport ◽  
Wind Tunnels ◽  
Subsonic Wind Tunnel ◽  
Validation Of Results ◽  
Mathematical Relations ◽  
Test Objects

Wind tunnels are the most widely used tools when comes to validation of Reynold number. Most of wind tunnels use various air straighteners or flow conditioners to achieve as most unified air flow as it’s possible. This article deals with design and creation procedure of air flow straightener – honeycomb screen. Based on mathematical relations and empirical experience defines dimensions and characteristics for subsonic wind tunnel of the Air Transport Department of University of Žilina. Wind tunnel equipped with a suitable screen provides more relevant and accurate data, which are crucial for final validation of results of test objects.

scholarly journals Design, Construction and Commissioning of the Braunschweig Icing Wind Tunnel

2017 ◽  
Author(s):  
Stephan E. Bansmer ◽  
Arne Baumert ◽  
Stephan Sattler ◽  
Inken Knop ◽  
Delphine Leroy ◽  
...  
Keyword(s):  
Wind Tunnel ◽  
Test Section ◽  
Measurement Techniques ◽  
Convective Cloud ◽  
Ice Crystals ◽  
Wind Tunnels ◽  
Comprehensive Overview ◽  
Tropical Regions ◽  
Water Contents ◽  
Design Construction

Abstract. Beyond its physical importance in both fundamental and climate research, atmospheric icing is considered as a severe operational condition in many engineering applications like aviation, electrical power transmission and wind-energy production. To reproduce such icing conditions in a laboratory environment, icing wind tunnels are frequently used. Creating and maintaining a stable icing cloud in the tunnel test section yields different design constraints compared to conventional wind tunnels. In this paper, a comprehensive overview on the design, construction and commissioning of the Braunschweig icing wind tunnel is given. The tunnel features a test section of 0.5 m x 0.5 m with peak velocities of up to 40 m/s. The static temperature ranges from −25 °C to +30 °C. Supercooled droplet icing with liquid water contents up to 3 g/m³ can be reproduced. Outstanding ability of the tunnel is to simulate ice crystal icing with natural ice crystals for ice water contents up to 20 g/m³. We further show, how current state-of-the-art measurement techniques for particle sizing perform on ice crystals. The data is compared to those of in-flight measurements in mesoscale convective cloud systems in tropical regions. Finally, some applications of the icing wind tunnel are mentioned.

scholarly journals Investigation of Throttling Characteristics in Supersonic Polyclinic Inlet

2019 ◽  
pp. 21-33
Author(s):  
D.A. Vnuchkov ◽  
V.I. Zvegintsev ◽  
D.G. Nalivaychenko
Keyword(s):  
Numerical Simulation ◽  
Experimental Investigation ◽  
Wind Tunnel ◽  
Flow Field ◽  
Air Flow ◽  
Flow Restriction ◽  
Air Inlet ◽  
Additional Heating ◽  
Flat Flow ◽  
Good Agreement

This paper presents an experimental investigation of throttling characteristics of a multi-wedge air inlet of a wind tunnel built for flat flow field at M = 2.5. The experiments were performed in a wind tunnel at M numbers of 2.55, 3.05 and 4.05. Results of numerical simulation of the flow in the air inlet, where air flow restriction was implemented by additional heating of the flow in the channel past the air inlet, are given for comparison. Experimental throttling characteristics are in good agreement with the values obtained from computations

scholarly journals Lift Interference in Wind Tunnels with Perforated and Solid Walls

2021 ◽  
Vol 13 (1) ◽  
pp. 105-111
Author(s):  
Mihaela MANEA ◽  
Adrian BURGHIU
Keyword(s):  
Wind Tunnel ◽  
Classical Theory ◽  
Test Section ◽  
Angle Of Attack ◽  
Wind Tunnels ◽  
Wind Tunnel Testing ◽  
Principle Of Superposition ◽  
Tunnel Wall ◽  
Test Article ◽  
Solid Walls

In order to obtain accurate results in wind tunnel testing it is necessary to determine the effect of interaction between the flow around the model and the test section walls. In this paper, the classical theory for wind tunnel wall corrections assessment is used to evaluate the wall induced change in the circulation caused by the presence of the test article in the wind tunnel. This primary correction, also known as lift interference is based on the test section geometry and it is applied to the test article angle of attack. The computations performed in this paper employ the assumption of the potential linearized flow between the test section walls and the model. As well, the principle of superposition is a key element in this analysis.

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