An experimental study of the vortical structure of turbulent flows.
Item
-
Title
-
An experimental study of the vortical structure of turbulent flows.
-
Identifier
-
AAI9417471
-
identifier
-
9417471
-
Creator
-
Honkan, Anant Gangadhar.
-
Contributor
-
Adviser: Yiannis Andreopoulos
-
Date
-
1994
-
Language
-
English
-
Publisher
-
City University of New York.
-
Subject
-
Engineering, Mechanical
-
Abstract
-
An attempt is made to explore the structures of a two-dimensional turbulent boundary layer flow and vortex flow over a 45{dollar}\sp\circ{dollar} sweep delta wing by spatio-temporal measurements of velocity and vorticity vectors and vorticity flux at the boundaries. Two novel probes, with good spatial resolution, one to measure multi-point velocity vector and the other to measure vorticity flux have been designed and constructed. Tests results of the principal statistical properties computed from the measurements of instantaneous velocity and vorticity vectors in the turbulent boundary layers at {dollar}Re\sb\theta = 2244{dollar} and {dollar}Re\sb\theta = 2790{dollar} are extensively compared with existing datasets including those from direct numerical simulations at various Reynolds numbers and under different flow conditions. The conditionally sampled results of the inclination of vorticity vector at the position closest to the wall suggest preferential orientation in the upper and lower quadrants. The turbulent structures identified by the conditional technique that are associated with streamwise vorticity seem to be of longer duration than those with the conditioned events of normal and spanwise vorticity. The probability of the orientation of vorticity vector as referred to the eigen vectors of the strain rate matrix closest to the wall, indicated this vector to be least likely to align with the most compressive eigen vector. The capabilities of the probe to measure the statistical quantities in both turbulent boundary layer flows with good accuracy were thus established and experimental data of time dependent three-dimensional vorticity field using this probe is collected for the first time in the region of strong vortices over a 45{dollar}\sp\circ{dollar} sweep delta wing to investigate the complex structure of the leading edge vortices for a case without vortex breakdown. Flow visualization technique employing laser sheet is used to observe instantaneous "frozen" coherent structures in the flow in three different perspectives.
-
Type
-
dissertation
-
Source
-
PQT Legacy CUNY.xlsx
-
degree
-
Ph.D.
