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turbulent-intensities
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Total 23 records
Experimental investigation on turbulence intensity reduction in subsonic wind tunnels
, Article Aerospace Science and Technology ; Volume 15, Issue 2 , 2011 , Pages 137-147 ; 12709638 (ISSN) ; Soltani, M. R ; Manshadi, M. D ; Sharif University of Technology
Abstract
Experiments are performed to evaluate the impact of trip wires on the turbulence intensity in a few low speed wind tunnels. Trip wires of different sizes are installed at different positions in the contraction section of four different wind tunnels and measurements are made at various free stream velocities. The results indicate that the pressure distributions are altered compared to the clean condition. Trip wires move the adverse pressure gradient toward the inlet of the contraction section. Consequently, the turbulence intensity in the test section of the wind tunnels is reduced and the flow uniformity is improved considerably. Frequency and statistical analysis are performed and the...
Experimental study on correlation between turbulence and sound in a subsonic wind tunnel
, Article Acta Mechanica Sinica/Lixue Xuebao ; Volume 26, Issue 4 , 2010 , Pages 531-539 ; 05677718 (ISSN) ; Ghorbanian, K ; Soltani, M. R ; Sharif University of Technology
Abstract
In this paper, the effects of turbulence on sound generation and velocity fluctuations due to pressure waves in a large subsonic wind tunnel are studied. A trip strip located at different positions in the contraction part or at one position in the diffuser of a large wind tunnel is used to investigate the aforementioned phenomenon, and the results indicate that the trip strip has significant effects on sound reduction. The lowest turbulence intensity and sound are obtained from a trip strip with a diameter of 0.91mm located either at X/L = 0.79 or at X/L = 0.115 in the wide portion of the contraction. Furthermore, the effect of monopole, dipole and quad- rupole sources of aerodynamic noise...
Numerical study of heat and mass transfer in underexpanded sonic free jet
, Article International Journal of Heat and Technology ; Volume 35, Issue 4 , 2017 , Pages 959-968 ; 03928764 (ISSN) ; Farhanieh, B ; Afshin, H ; Sharif University of Technology
Abstract
In case of unexpected ruptures in high pressure tanks, choking phenomenon occurs in the cracked area which fluid velocity gets sonic and its pressure exceeds atmospheric pressure. Afterward, pressure of discharged gas quickly changes by crossing through compression and expansion shock waves. The main aim of this study was numerical simulation and investigation of this flow in a 3-step process: (a) Detailed analysis of numerical method, (b) Qualitative and quantitative analysis of velocity, pressure, temperature and turbulence intensity, in order to propose safety strategies and (c) parametric studies on the effects of tank pressure and nozzle geometry on flow structure. In numerical...