An Experimental Investigation of the Characteristics of Turbulence in a Triangular Duct PDF Download

Author: Clifford John Cremers
Publisher:
ISBN:
Category : Fluid dynamics
Languages : en
Pages : 230

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Author: Donald Hiroshi Tanaka
Publisher:
ISBN:
Category : Navier-Stokes equations
Languages : en
Pages : 72

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Book Description
The study of flow induced phenomena at the interface between a solid body and a fluid in contact with it is essential to the understanding of such vital engineering problems as drag, flow noise and other energy dissipation characteristics of turbulent flow. At present, investigations have been made of flow properties near a solid boundary and the results extrapolated to the boundary itself by means of energy and momentum conservation principles. The results of these experiments tend to support the theory; however, the data is sparse and many assumptions and secondary mathematical relations must be used before this can be achieved. In this study shear stress was measured at the wall itself using flush-mounted hot-film anemometers. The purpose was to test two models of the structure of the viscous sublayer. The test apparatus consisted of a pipe four inches in diameter and forty feet long connected to a water reservoir in a closed loop design. The test section was located near the end of the pipe to assure fully developed flow conditions. Fluctuating wall shear stress was measured to determine a model of the viscous sublayer.

Author: Charlene A. Caulfield
Publisher:
ISBN:
Category : Fluid dynamic measurements
Languages : en
Pages : 82

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Author: David O. Davis
Publisher:
ISBN:
Category : Air ducts
Languages : en
Pages : 482

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Author: Vaidyanathan Krishnan
Publisher:
ISBN:
Category : Air ducts
Languages : en
Pages : 72

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Book Description
An experimental investigation was performed to ascertain the nature of turbulence in a narrow apex angle isosceles triangular duct. The study involved the design and construction of a low noise, low turbulence wind tunnel that had an isosceles triangular test section with an apex angle of 11.5°. Experiments involved the measurement of velocity fluctuations using hot wire anemometry and wall pressure fluctuations using a condenser microphone. Measurement of the velocity fluctuations reconfirms the coexistence of laminar and turbulent regions at a given cross section for a range of Reynolds numbers. The laminar region is concentrated closer to the apex while the turbulent region is found closer to the base. The point of transition is a function of the Reynolds number and moves closer to the apex as the flow rate is increased. Moreover, it was found in this investigation that traditional scaling of the turbulent statistical quantities do not hold good in this geometry. Although velocity fluctuations showed distinctive flow regimes, no such distinction could be seen in the dynamic wall pressure data. The nature of the dynamic wall pressure was uniform throughout the entire cross section suggesting that wall pressure fluctuations, unlike the velocity fluctuations, are able to travel from the base to the apex, without being damped. This implies that the relationship between the velocity and the pressure fluctuations applicable in the other systems does not hold well in a narrow apex angle isosceles triangular duct. Further, the typical scaling relationships applied to wall pressure spectra of other geometries doesn't apply in this scenario and the ratio of the RMS pressure fluctuation to the mean shear is much higher compared to a flat plate or pipe flow situation.

Author: Richard E. Stakutis
Publisher:
ISBN:
Category : Fluid dynamic measurements
Languages : en
Pages : 316

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Author: Sumnesh Mathur
Publisher:
ISBN:
Category :
Languages : en
Pages : 430

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Author: Bayode Owolabi
Publisher: Springer
ISBN: 303019745X
Category : Science
Languages : en
Pages : 141

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Book Description
This book presents several new findings in the field of turbulent duct flows, which are important for a range of industrial applications. It presents both high-quality experiments and cutting-edge numerical simulations, providing a level of insight and rigour rarely found in PhD theses. The scientific advancements concern the effect of the Earth’s rotation on large duct flows, the experimental confirmation of marginal turbulence in a pressure-driven square duct flow (previously only predicted in simulations), the identification of similar marginal turbulence in wall-driven flows using simulations (for the first time by any means) and, on a separate but related topic, a comprehensive experimental study on the phenomenon of drag reduction via polymer additives in turbulent duct flows. In turn, the work on drag reduction resulted in a correlation that provides a quantitative prediction of drag reduction based on a single, measurable material property of the polymer solution, regardless of the flow geometry or concentration. The first correlation of its kind, it represents an important advancement from both a scientific and practical perspective.

Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 0

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An experimental investigation was conducted to examine the convective heat transfer in straight and curved ducts of rectangular cross-section. The experimental configuration was modeled as infinite parallel plates with one wall at a constant temperature and the opposite wall adiabatic. The experiments were conducted at steady state for turbulent flow. Average Nusselt numbers were used to compare the heat transfer characteristics of the straight and curved sections. The development of Taylor-Gortler vortices in the curved section was shown to enhance the heat transfer rate in the curved section as compared to that of the straight section by approximately 15 to 20 percent. Improved heat exchanger designs and improved cooling of turbine blades are two disciplines that could benefit from a better understanding of the effects of curvature on the rate of heat transfer. (Author).

Author: Joel L. Wilson
Publisher:
ISBN:
Category : Heat
Languages : en
Pages : 162

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Book Description
An experimental investigation has been conducted to examine the convective heat transfer in straight and curved ducts of rectangular cross section. The experimental configuration was modeled as infinite parallel plates with one wall at a constant heat flux and the opposite wall adiabatic. Experiments were conducted at steady state for turbulent flow using average Nusselt numbers to compare the heat transfer characteristics of the straight and curved sections. The development of Taylor-Gortler vortices in the curved section proved to enhance the heat transfer rate over that of the straight section. Improved heat exchanger and turbine blade design could both result from a better understanding of the effects of curvature on the rate of heat transfer. Originator-supplied keywords: Taylor-Gortler vortices, Heat transfer; Secondary flow; Rectangular curved channel; Rectangular straight channel; Temsheet; Joulean heating; and Turbulent flow.