Design of a small-scale wind tunnel for the study of horizontal-axis wind turbine blades

In this study, the design of a wind tunnel was carried out to observe airflow through an airfoil, streamlines and turbine blades. To accommodate this, in this study a design was made of an open return wind tunnel. In this case, an open circuit wind tunnel type will be made because the construction is simpler and the manufacturing costs are relatively cheaper compared to the closed circuit wind tunnel type. The Wind Tunnel is designed with Open CLosed Wind Tunnel (OCWT) type. The OCWT is designed to consist of fan and housing, diffuser, test section, contraction, honeycomb. The OCWT design uses an operating fan to circulate air into the test section. The maximum air speed in the Test Section is 5 m/s with a flow that is closed to laminar. The recommended diffuser has a dimension of 50 cm on the side that is attached to the test section and 52 cm on the side facing the fan with an inclination angle of 1.79o. The driver uses a 16 inch exhaust fan with a power of 74 W to make the flow in the Test Section stable at a speed of 2 m/s.

The design, construction, and validation of a new academic wind tunnel is described in detail. The wind tunnel is of a classical, blow-down type and generates a pressure-driven, turbulent separation bubble on a flat test surface. The Reynolds number, based on momentum thickness just upstream of separation, is Reθ ' 5000 at a free-stream velocity of Uref = 25 m/s. The length of the separation bubble has been estimated at 0.42 ± 0.02 m by three different methods. Experimental and numerical results demonstrate the absence of flow separation in the wind-tunnel contraction. This results in a turbulence level of about 0.05% in the test section. Oil-film visualization experiments show that the flow near the wall is strongly three-dimensional in the recirculating region and that the topology of the limiting streamlines is consistent with experiments performed on configurations with fixed separation. Finally, spatial variations of the forward-flow fraction have been documented using a thermal-tuft probe and are shown to compare well with the results of the oil-film visualization.

The global demand for renewable energy sources has led to an increase in development and installation of wind turbines. However, noise regulations on wind turbines near populated areas can restrict the installation of new wind turbines and limit the potential energy production. The main noise from wind turbines is aerodynamic and arises from turbulence caused by the air flow around the wind turbine blades in motion. The aerodynamic noise increases with the size of the wind turbine, and with a demand for more productive, and thus larger wind turbines, there is an increased interest in quantifying the aerodynamic noise from wind turbine blades. This thesis investigates experimental methods for estimating the noise of wind turbine blades in a newly-established wind tunnel – the Poul la Cour Tunnel (PLCT). This study has three focus areas; the acoustic design of the wind tunnel airline, the measurement conditions and sound propagation properties in the anechoic, Kevlar-walled test section, and the quantification of trailing edge noise of wind turbine blade sections. The attenuation of background noise (from the wind tunnel airline) is a crucial part of successful acoustic measurements. To investigate this, the wind tunnel design was described and an experimental in-situ method proposed for determining transmission losses of the acoustically treated wind tunnel airline components. The results were compared to a numerical study that was conducted prior to construction, showing good agreement and thereby validating the general acoustic design. In the test section, acoustic measurements are made with a microphone array situated behind a tensioned Kevlar wall inside an anechoic room. The acoustic losses due to sound propagation through the Kevlar fabric was examined both with and without flow in several measurement setups. A comparison of methods and results was discussed and found to agree with the existing literature on the topic. Additionally, methods for quantifying absolute noise levels of an airfoil was examined. Several of these were applied to measurements of a NACA63018 airfoil at flow speeds ranging from about 30 m/s to 70 m/s (Reynolds numbers 2 mio. to 4 mio.) and corrections due to Kevlar losses were applied. The results were compared to a trailing edge noise model, finding good agreement. This dissertation describes the relevant contributions of the PhD study and places it in the context of current aeroacoustic wind tunnel research.

A wind tunnel with advanced capabilities will aid research efforts to understand the complex fluid structure interaction problems encountered in aerospace engineering, industrial aerodynamics and wind engineering applications since wind tunnels remain an integral component of the design process for wind sensitive structures. Whether dealing with the aerodynamics of aerospace, mechanical or civil engineering structures many issues remain to be fully resolved-including the role of non-stationary gust interactions, Reynolds number effects, and the significance of small-scale turbulence. Building the next generation of such wind tunnels will contribute to the understanding of these issues. A combination Aerodynamic/Atmospheric Boundary Layer (AABL) Wind and Gust Tunnel with a unique active gust generation capability has been developed for various applications at Iowa State University (ISU). This wind tunnel is primarily a closed-circuit tunnel that can be also operated in open-return mode. It is designed to accommodate two test sections (2.44m x 1.83m and 2.44m x 2.21m) with a maximum wind speed capability of 53 m/s. This paper describes the wind tunnel and its components and presents a comparison of the predicted and measured design parameters. It shows that the wind tunnel is capable of generating uniform flow with very low turbulence in the aerodynamic test section and produces gust magnitudes around 27% of the mean flow speed.

In the planning and design of a new wind tunnel the choice between closed and open-circuit types is a very important one. If on one hand the open –circuit solution is attractive for its low price and continuous fresh test air, on the other hand the test section flow quality is potentially affected by external winds. This sensitivity becomes especially critical at low-test speeds. Although many open-circuit wind tunnels have been built, there have been some problems either of low operating efficiency or sensitivity to external winds, or both. In this respect both ends of the tunnel are objects of concern. In the present paper, however, the authors concentrate their attention to the wind tunnel inlet section. At the Instituto Tecnologico de Aeronautica a non-return wind tunnel is currently under design. The test section flow quality requirements are very strict and the test-section turbulence level is to be as low as 0.05% of the mean flow kinetic energy. To insure that the desired turbulence level and flow uniformity at the test section is achieved the tunnel will have a 10:1 contraction, a honey comb and three screens with provision for an extra one. Further, the 35meter long facility has its inlet section, the contraction and the test section inside a 25x10 room. The diffuser, the fan section and the exit section are mounted outside the laboratory room. Figure 1 shows the tunnel layout. Although its position inside the laboratory is beneficial as does not expose the inlet section directly to the outside wind it also arises following concerns: (i) to operate the wind tunnel a large 6mx2.5m door will have to be open. Both side ends of this door will generate a shear layer exactly in front of the facility air intake (ii) the tunnel inlet section is not symmetrical in respect to the laboratory’s walls, being much closer to the one on its right-hand side. The 3.8m wide by 3.16 m high inlet is only about 20 cm away from both the floor and the ceiling of the room. In order to quantify these influences on the mean velocity distribution and on the turbulence level, at the tunnel air intake, an experimental study was made on a 1/10 scale model of the part of the tunnel to be built inside the lab.

The wind tunnel is an arrangement to simulate real aerodynamic parameters. An open circuit wind tunnel does not circulate the same fluid as working fluid rather uses environmental fluid circulated by a fan. This research paper documents the design, construction, and setup of a low-speed subsonic open wind tunnel at the National Innovation Center, Kirtipur. This wind tunnel produces a controlled stream of air to test the aerodynamic properties of objects or fluids. The wind tunnel developed at NIC is used for a variety of research activities related to the aerodynamics of different bodies such as testing of lift coefficient, drag coefficient, and pressure difference calculations on drones and rockets along with flow visualization in civil works signature bridges and high-rise buildings. Designed to be a general-purpose wind tunnel, it is the biggest of its kind in Nepal.

This paper presents the design and manufacturing of open circuit low-speed wind tunnel. The design of the contraction cone, test section and diffuser are finalized by the numerical analysis performed on ANSYS CFD software. A unique insight into the design of the contraction cone is presented. A fifth-order polynomial is used to model the contraction cone in PRO-E software. It allowed designing the test section with minimum turbulence and flow serration and a flow velocity profile of 20 m/s. The cross-sectional area of the test section and diffuser are selected after analytical calculations. The diffuser is designed as such to avoid pressure loss by incorporation changes in the rectangular cross-section. The initial study performed on the design helped us to select the fan with suitable power. Moreover, the intake of the contraction cone is equipped with the honeycomb structure of facilitating the laminar flow into the contraction cone. Following on to the initial numerical analysis, the fabrication of the wind tunnel is performed. Besides, a separate lift/drag measuring force system is also prepared; the intuitive design is cost-effective as well as accurate. The placement of anemometer helped us to directly measure the test section velocity, which is found to be 17 m/s.

On the basis of the overall structure design and aerodynamic calculation of the annular low-speed wind tunnel, this paper uses the CFD numerical simulation technique to study the influence of the contraction curve form, the contraction ratio and the open/closed loop form of the test section on the flow field quality of the wind tunnel test section, and then gives the three-dimensional geometric model and the numerical simulation results. It is found that the best flow field quality can be obtained by using the bicubic curve, the contraction ratio of 10.24 and the closed loop form of the test section under the same fan condition. The three-dimensional modeling method is adopted in this paper, which can obtain more accurate numerical simulation result than the two-dimensional modeling method. Thus, the numerical simulation result provides a solid theoretical basis for the design and construction of the actual low-speed wind tunnel.

The design, construction, and validation of a new academic wind tunnel is described in detail. The wind tunnel is of a classical, blow-down type and generates a pressure-induced, turbulent separation bubble on a flat test surface by a combination of adverse and favorable pressure gradients. The Reynolds number, based on momentum thickness just upstream of separation, is Reθ≃ 5,000 at a free-stream velocity ofUref= 25ms−1. The length of the separation bubble is estimated at 0°42 ± 0°02m by three different methods. Results of a numerical simulation demonstrate the absence of flow separation in the wind-tunnel contraction. This results in a turbulence level of about 0·05% in the test section. Oil-film visualisation experiments show that the flow near the wall is strongly three-dimensional in the recirculating region and that the topology of the limiting streamlines is consistent with experiments performed on configurations with fixed separation. Finally, spatial variations of the forward-flow fraction have been documented using a thermal-tuft probe and are shown to compare well with the results of the oil-film visualisation.

The design of a new transonic wind tunnel to reproduce bypass aero-engine flow conditions is described. This study has been driven by the interest to investigate and optimize the aero-thermal effects of an air/oil integrated surface heat exchanger placed at the inner wall of the secondary duct of a turbofan. The test section of the intermittent wind tunnel consists of a complex three-dimensional (3D) geometry. The flow evolves over the splitter, duplicated at real scale, as it does in the engine, guided by helicoidally shaped lateral walls. Numerical flow analyses have been used to guide the design of the complete wind tunnel. Zero-dimensional models have been developed to recreate the wind tunnel behaviour. Two- and three-dimensional computations have been performed to optimize the test section and the inlet guide vanes that duplicate the flow downstream of the engine fan. The reproduction of the bypass flow structure has been numerically analysed. Flow computations with and without the presence of instrumentation in the test section have been contrasted. Additionally, the influence of an aerodynamic probe on the flow has been studied numerically. This study should lead to improvements in the thermal management of future aircraft power plants, particularly by taking benefit of the cold bypass air to refrigerate the lubrication oil, without penalizing the propulsive efficiency.

Design and construction of an open loop subsonic high temperature wind tunnel for investigation of SCR dosing systems

A multipurpose subsonic wind tunnel facility has been designed for the Korea Air Force Academy in South Korea, and construction of this facility is nearing completion. This wind tunnel will be used in development of aircraft and ground vehicles as well as for basic studies in aeronautical engineering. The facility includes the wind tunnel and a building complex with offices, workshops, and test hall. The main test section dimensions are 2.45 m high, 3.5 m wide and 8.7 m long. Velocity ranges from 5 to 92 m/s with a fan power of 2,000 kW. High flow quality is achieved, with turbulence intensity designed to be below 0.05%rms (u'/U) and 0.1%rms (v'/U, w'/U). How angularity is designed to be less than +.0.1 deg. The wind tunnel has interchangeable test sections, several model support systems, a variety of instrumentation systems, and a probe traverse system. The external balance can be elevated to provide high accuracy for the various model types and to accommodate model/test section exchanges. The test facility systems and the building are integrated to provide excellent model handling and testing productivity. *Cheong-Ju, South Korea t Tullahoma, Tennessee 37388 Copyright * 1998 by Sverdrup Technology, Inc. Published by American Institute of Aeronautics and Astronautics, Inc., with permission. INTRODUCTION The government of the Republic of Korea and Korean industry are committed to establishing the capability for future aircraft development in Korea. The scope of this capability includes both military and civil systems. To meet this commitment, wind tunnels of sufficient size and capability are required. Several projects are now underway to support this effort. One of them, a subsonic wind tunnel undertaken by the Republic of Korea Air Force Academy (KAFA), is the subject of this paper. KAFA selected Sverdrup Technology, Lie. as the turnkey supplier of the subsonic wind tunnel, including preliminary and final design and construction services. Final design work has been completed and is covered in the present paper. Construction/installation and commissioning/calibration phases will be completed in 1998, and the results of that work will be presented in a future paper. FACILITY REQUIREMENTS During initial facility planning studies, KAFA configured the Subsonic Wind Tunnel as a closedcircuittype with interchangeable, atmospheric-pressure test sections. To support the Republic of Korea's commitment to aircraft and ground vehicle systems, the main testing activities planned to be conducted in the facility are: • Configuration optimization of aircraft • Development of high hit devices • Wing/body integration American Institute of Aeronautics and Astronautics Copyright© 1997, American Institute of Aeronautics and Astronautics, Inc. • Ground passenger vehicle aerodynamics • Building aerodynamics • Full aircraft component integration • Rotor aerodynamics • Helicopter aerodynamics Facility design requirements were established based on these testing activities. The requirements for test-type, test section size, performance, and flow quality are summarized in Tables 1 and 2. Compared to other mediumand large-size subsonic facilities, the KAFA facility's performance and flow quality requirements are state-of-the-art, and they are appropriate for advanced experimental education programs and aircraft development programs.

The wind tunnel is proper functioning platform for accurate aerodynamic research which helps to provides adequate environment condition around scaled model to the compatible dimension. Wind tunnel data is part of design process that used to design their model. For correcting wind tunnel data of wall and mounting effects very careful techniques are used. But it shows limitation for linear flow approximation. This research paper proposed first part of the project i.e. design calculation and simulation i.e. flow in wind tunnel and checking incompressible flow in test section over an airfoil using CFD software. Test section design in rectangular shape for proposed wind tunnel. Contraction cone has contraction ratios 7 and cross section in rectangular shape. Diffuser design in conical shape with 5° diffusion angle and area ratio 1.33. The design philosophy is discussed along method for wind tunnel calculation is outlined. Using Computational fluid dynamics (CFD), design and simulation of flow parameter are investigated with systematic way in open loop wind tunnel. It shows good quality flow in test section as well as in entire wind tunnel. The proposed wind tunnel is conformed to design and can be used for different test in the field of aerodynamics. Wind tunnel design to achieve 40 m/s speed of air with expected low intensity turbulence level. Analysis of airfoil shows that good flow quality in test section. Lift and drag coefficient plotted against angle of attack.

The design and fabrication of a low-speed wind tunnel (LSWT), which is a critical component for testing and comprehending aircraft aerodynamics, is presented in this study. Despite the increasing prominence of computational fluid dynamics (CFDs) in manufacturing engineering, wind tunnels remain essential for the intricate development of aircraft and automobile designs with complex flow interactions. Using SolidWorks, we focused on controlling flow turbulence approaching the test section, emphasizing performance and quality parameters. The construction of the wind tunnel used plywood with an axial fan regulating the airspeed, and Arduino facilitated data acquisition. The drag and lift on the Y Clerk Airfoil were quantified by two load cells along the XY-axis, complemented by a Pitot Static Tube and a multitube inclined plane manometer for pressure and velocity calculation. Fusion 360 simulation software was used to analyze pressure and velocity profiles at speeds ranging from 10 to 20 m/s, providing a comprehensive quantitative evaluation of the wind tunnel’s capabilities. By emphasizing both design innovation and quantitative performance metrics, this study underscores the continuing significance of wind tunnels in engineering.

Design and performance of a small-scale aeroacoustic wind tunnel