Title page for ETD etd-06222010-020336
|Type of Document
||Gupta, Tej R.
||Two and three-dimensional incompressible and compressible viscous fluctuations.
|Telionis, Demetri P.
|McNitt, R. P.
|O'Brien, Walter F. Jr.
|Smith, Charles W.
|Tieleman, Henry W.
|Date of Defense
Small unsteady disturbances of boundary-layer flow fields are often
encountered in engineering applications, as for example, in the aerodynamics
of a helicopter rotor or a turbine cascade or in a fluttering
airfoil as well as in a variety of bioengineering problems. The present
dissertation is a unified attempt to study some special classes of
unsteady two- and three-dimensional incompressible and compressible
. boundary-layer flows. The general character of the mathematical problem
is investigated first for each particular area. Asymptotic solutions
are then provided based on the assumption of small amplitude and small
frequency of oscillation. Systems of general differential equations in
a single variable are obtained and solved numerically by the shooting
technique. A straightforward fourth order Runge-Kutta integration
scheme is employed and the values of the functions at the edge of the
boundary-layer are checked against the outer flow boundary conditions.
In the first chapter we study simultaneously the effects of three dimensionality
coupled with the response to outer flow oscillations. It
is believed that the coupling will have significant implications in
cascade flows where the finite span blocks the development of cross
flows. Some interesting features of oscillatory three-dimensional flows
are disclosed. In particular it is found that the coupling of the
momentum equations permits the transfer of momentum from the chordwise
to the spanwise direction. In this way it is possible to excite a
fluctuating boundary layer flow in the spanw;se direction even though
there ;s no outer flow fluctuations. In the second chapter the response
of laminar compressible boundary layers to fluctuations of the skin of
the body or the outer flow are studied in the special case of a wall at
the adiabatic temperature. Unsteady outer pressure fluctuations are
considered for the first time and their effects to the energy equation
and heat transfer is estimated. The analysis holds both for two-dimensional and axisymmetric configurations.
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