TY - JOUR

T1 - Influence of the axisymmetric contraction ratio on free-stream turbulence.

AU - Ramjee, V.

AU - Hussain, A. K.M.F.

N1 - Copyright:
Copyright 2017 Elsevier B.V., All rights reserved.

PY - 1976

Y1 - 1976

N2 - The effect of axisymmetric contractions of a given shape and of contraction ratios c equals 11, 22, 44.5, 64 and 100 on the free-stream turbulence of an incompressible flow has been studied experimentally with hot-wires. It is found that the longitudinal and lateral kinetic energies of turbulence increase along the contraction. The monotonic increase of the longitudinal turbulent kinetic energy with increasing c is in contrast with the linear (Batchelor/ Proudman/Ribner/Tucker) theory. The variation of the lateral turbulent kinetic energy with c is in qualitative agreement with the theory; however, th increase is much lower than that predicted by the theory. The linear theory overpredicts the decrease in the longitudinal turbulence intensity with increasing c and under-predicts the decrease in the lateral turbulence intensity with increasing c. For the given flow tunnel, it is found that a contraction ratio c greatee than about 45 is not greatly effective in reducing longitudinal turbulence levels further; the lateral turbulent intensity continues to decrease with increasing c. In the design of a low turbulence-level tunnel, the panacea for the reduction of the turbulence level does not lie in an indefinite increase of the contraction ratio alone. Studies with various upstream screens and a given contraction of c equals 11 suggest that the exit turbulence intensities are essentially independent of the Reynoldsnumber based on the screem-mesh size or screen-wire diameter of the upstream screen. (A)

AB - The effect of axisymmetric contractions of a given shape and of contraction ratios c equals 11, 22, 44.5, 64 and 100 on the free-stream turbulence of an incompressible flow has been studied experimentally with hot-wires. It is found that the longitudinal and lateral kinetic energies of turbulence increase along the contraction. The monotonic increase of the longitudinal turbulent kinetic energy with increasing c is in contrast with the linear (Batchelor/ Proudman/Ribner/Tucker) theory. The variation of the lateral turbulent kinetic energy with c is in qualitative agreement with the theory; however, th increase is much lower than that predicted by the theory. The linear theory overpredicts the decrease in the longitudinal turbulence intensity with increasing c and under-predicts the decrease in the lateral turbulence intensity with increasing c. For the given flow tunnel, it is found that a contraction ratio c greatee than about 45 is not greatly effective in reducing longitudinal turbulence levels further; the lateral turbulent intensity continues to decrease with increasing c. In the design of a low turbulence-level tunnel, the panacea for the reduction of the turbulence level does not lie in an indefinite increase of the contraction ratio alone. Studies with various upstream screens and a given contraction of c equals 11 suggest that the exit turbulence intensities are essentially independent of the Reynoldsnumber based on the screem-mesh size or screen-wire diameter of the upstream screen. (A)

UR - http://www.scopus.com/inward/record.url?scp=0016886031&partnerID=8YFLogxK

M3 - Article

AN - SCOPUS:0016886031

VL - 98

SP - 506

EP - 515

JO - Journal of Fluids Engineering, Transactions of the ASME

JF - Journal of Fluids Engineering, Transactions of the ASME

SN - 0098-2202

IS - 3 ,Sep.1976

ER -