A Rational Method to Choose Optimum Design for Two-Dimensional Contractions

Ramaseshan, S.; Ramaswamy, MA

doi:10.1115/1.1456463

Cited by 8 publications

(6 citation statements)

References 3 publications

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“…The most extended contraction profiles used for wind tunnels, which have been widely tested and recommended for this type of applications in the literature, are those based in a pair of two cubic polynomials [1][2][3][4]. This family of profiles could not be adapted in our case due to some unavoidable geometrical restrictions of the wind tunnel.…”

Section: Nozzle Contours Studiedmentioning

confidence: 99%

“…A good choice is a crucial milestone to assure high-quality flow characteristics and, therefore, it deserves special attention. Typically, converging nozzles have been constructed using a pair of cubic polynomials where, for a fixed length and contraction ratio, the location of the joining point has been found to be determinant in the optimization of the designs [1][2][3][4]. Years ago, the analytical resolution of inviscid flow equations to study the flow field, required a lot of time.…”

Section: Introductionmentioning

confidence: 99%

“…Years ago, the analytical resolution of inviscid flow equations to study the flow field, required a lot of time. For that reason, design charts for nozzles were developed, and recurrent calculations were avoided [1][2][3][4][5][6]. However, due to the great computational advances and the development of more efficient codes, CFD has currently become an essential tool to optimize wind tunnel contractions.…”

Section: Introductionmentioning

confidence: 99%

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Novel design and experimental validation of a contraction nozzle for aerodynamic measurements in a subsonic wind tunnel

Lastra¹,

Oro²,

Vega³

et al. 2013

Journal of Wind Engineering and Industrial Aerodynamics

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A novel design for a contraction nozzle, based on a logarithmic profile, is presented and developed to enhance aerodynamic measurements in a low-speed wind tunnel. The improvements obtained with this new proposal are validated, both, numerical and experimentally. As a starting point, four different wind tunnel contraction profiles are firstly considered and tested using the Computational Fluid Dynamics (CFD) package ANSYS FLUENT®. Both polynomial, due to its classical inclusion for wind tunnels, and logarithmic profiles, due to its expected enhancement, have been studied in terms of avoidance of separation of the boundary layer, procurement of a maximum level of exit-flow uniformity, and minimum turbulence levels at the outlet. Numerical comparison between obtained results shows the benefits of the new logarithmic profile developed by the authors, which was finally employed to construct the nozzle. To characterize its real performance, intensive experimental measurements have been conducted using pressure transducers and both single and dual hot wire anemometry. The pressure coefficient along the nozzle sidewall reveals an optimal evolution, matching perfectly with the theoretical design. In addition, low levels of turbulence and high flow uniformity is confirmed at the nozzle discharge. Turbulence intensities below 0.7% are obtained for the whole range of velocities available in the wind tunnel, and even practically constant uniform flow is obtained for all the traverses tested for validation. These indicators conclude that the contraction designed with the new profile is a good enhancing of the wind tunnel benefits.

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Section: Nozzle Contours Studiedmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Novel design and experimental validation of a contraction nozzle for aerodynamic measurements in a subsonic wind tunnel

Lastra¹,

Oro²,

Vega³

et al. 2013

Journal of Wind Engineering and Industrial Aerodynamics

View full text Add to dashboard Cite

show abstract

“…Therefore, long term factors such as flexibility of design and upgrade were considered. Review of literature for tunnel design quickly revealed that the existing inlet convergence profile, while appropriate, was not optimal and that the convergence ratio was too low to assure good flow quality within the test section 1,5,8,10 .…”

Section: Introductionmentioning

confidence: 99%

Experimental Study Of Waste Egress From Collection Vehicle

Cuprak

Rajadas

Georgeou

2008 Annual Conference &Amp; Exposition Proceedings

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be made with minimum effort in the future. On the instrumentation front, pressure transducers and a data-logger were fully integrated with the wind tunnel measurement system. Variable inputs were geometric design parameters related to the truck cab and the collection bin sections, wind speed, and yaw angle (cab orientation). Output was dynamic pressure from fifty-four test points in the truck. Statistical analysis of normalized data using Minitab ® included analysis of variance, linear regression analysis to establish significant input variables, and contour plots of the pressure fields generated in Excel ®. The main effects account for half of the measured response, there are interactions between some main effects, and other probable variables exist. Brief descriptions of the changes to the wind tunnel, design and fabrication of the truck models, factorial design, and the experimental process are given below. As mentioned above, the experimental study described in the present paper supported a M.S. Thesis work in the department. The investigation was comprehensive, rigorous and led to useful results and information that will be of immediate use to the industry at large. Additionally the tasks associated with the study such as the use of rapid prototyping equipment for making the test models will serve as the template for future such endeavors. Even though the redesigned tunnel was used to address the specific problem faced by the industry right now, the students gain valuable experience in solving practical problems of interest to present day industry as they work on a variety of applied projects using the tunnel.

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“…The contraction ratio (CR), overall length, and wall contour shape all affect the degree of flow uniformity, turbulence intensity reduction, and boundary layer growth of the flow entering the test section[43,52,61]. Ideally, nozzles should be designed to be as short as possible to minimize frictional pressure losses while also containing a large contraction ratio which aids in attenuating both mean and fluctuating velocity variations.Careful design of the shape of the wall contours must also be considered as separation can occur in regions of sharp changes in streamline curvature, thus leading to poor test section flow quality[61][62][63]. Possible separation in contractions can be visualized by examining the typical normalized wall static pressure profile along the contour of a nozzle shown inFigure 2.16[44].The regions outlined by the blue circles in the wall static pressure distribution describe regions with positive slopes of wall static pressure; which indicates regions of adverse pressure gradients and possible flow separation.…”

mentioning

confidence: 99%

The Design, Fabrication, and Commissioning of a High-Speed Aeroacoustic Wind Tunnel for Studies of Surface Pressure Fluctuations Beneath Turbulent Boundary Layers

Giardino¹

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The High-Speed Aeroacoustic Wind Tunnel (HSAWT) at Carleton University is a newly commissioned facility with the purpose of facilitating experimental studies of Turbulent Boundary Layer (TBL) induced surface pressure fluctuations. This research is intended for applications regarding aircraft noise generation from structures exposed to high-speed flow. This open-jet, blowdown facility is unique in Canada and one of a few aeroacoustic wind tunnels in the world capable of achieving speeds up to Mach 0.8. The details of the complete design and fabrication methodology for all wind tunnel duct components, control system hardware, and instrumentation systems is discussed; along with the numerical simulations performed in the validation of the designed components. Preliminary experimental flow measurements and characterization of the wind tunnel control system is examined. The results of initial measurements of TBL surface pressure fluctuations developed over a flat test section plate are compared with established data and empirical models in literature. iv Acknowledgements First and foremost, I would like to thank my thesis and research supervisor, Professor Joana Rocha, for her support and invaluable guidance provided throughout my entire Master's Degree program. Our countless free and open discussions during research meetings has helped me to develop a better understanding and appreciation regarding the complex topics of fluid mechanics and aeroacoustics. I have no doubt that my experiences the past couple of years as a part of her research team will benefit me in my future career initiatives and endeavors.

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A Rational Method to Choose Optimum Design for Two-Dimensional Contractions

Cited by 8 publications

References 3 publications

Novel design and experimental validation of a contraction nozzle for aerodynamic measurements in a subsonic wind tunnel

Novel design and experimental validation of a contraction nozzle for aerodynamic measurements in a subsonic wind tunnel

Experimental Study Of Waste Egress From Collection Vehicle

The Design, Fabrication, and Commissioning of a High-Speed Aeroacoustic Wind Tunnel for Studies of Surface Pressure Fluctuations Beneath Turbulent Boundary Layers

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