Approximate Formulas for the Computation of Turbulent Boundary-layer Momentum Thicknesses in Compressible Flows


Book Description

Summary: Approximate formulas for the computation of the momentum thicknesses of turbulent boundary layers on two-dimensional bodies, on bodies of revolution at zero angle of attack, and on the inner surfaces of round channels all in compressible flow are given in the form of integrals that can be conveniently computed. The formulas involve the assumptions that the momentum thickness may be computed by use of a boundary-layer velocity profile which is fixed and that skin-friction formulas for flat plates may be used in the computation of boundary-layer thicknesses in flow with pressure gradients. The effect of density changes on the ration of the displacement thickness to the momentum thickness of the boundary layer is taken into account. Use is made of the experimental finding that the skin-friction coefficient for turbulent flow is independent of Mach number. The computations indicated that the effect of density changes on the momentum thickness in flows with pressure gradients is small for subsonic flows.




Analysis of Turbulent Boundary Layers


Book Description

Analysis of Turbulent Boundary Layers focuses on turbulent flows meeting the requirements for the boundary-layer or thin-shear-layer approximations. Its approach is devising relatively fundamental, and often subtle, empirical engineering correlations, which are then introduced into various forms of describing equations for final solution. After introducing the topic on turbulence, the book examines the conservation equations for compressible turbulent flows, boundary-layer equations, and general behavior of turbulent boundary layers. The latter chapters describe the CS method for calculating two-dimensional and axisymmetric laminar and turbulent boundary layers. This book will be useful to readers who have advanced knowledge in fluid mechanics, especially to engineers who study the important problems of design.




Approximate Calculation of Turbulent Boundary-layer Development in Compressible Flow


Book Description

Numerical solutions of quantities appearing in the Karman momentum equation for the development of a turbulent boundary layer in plane and in radial compressible flows along thermally insulated surfaces are presented in tabular form for a range of Mach numbers from 0.100 to 10. Through the use of these tables, approximate calculation of boundary-layer growth is reduced to routine arithmetric computation. The variation of local skin-friction coefficient with Mach number is obtained through the assumption that the Falkner relation for low-speed flat-plate friction coefficents is dependent only on Reynolds number provided that the fluid properties are evaluated at the arithmetic mean of the wall temperature and the stream temperature.










An Approximate Method for the Calculation of the Reynolds Analogy Factor for a Compressible Turbulent Boundary Layer in a Pressure Gradient


Book Description

The method predicts that a positive pressure gradient increases and a negative pressure gradient decreases the ratio of Stanton number to friction coefficient. The Crocco relation between the velocity and total enthalpy for a non-adiabatic surface and zero pressure gradient is generalized to non-zero pressure gradient. The relation between the velocity and the total enthalpy varies markedly from the flat plate Crocco relation as the pressure gradient departs from zero. The magnitude of the variation depends on the velocity profile shape parameter. (Author).










The Turbulent Boundary Layer in a Compressible Fluid


Book Description

The first object of the paper is to develop a transformation which reduces the boundary-layer equations for compressible two-dimensional mean turbulent motion to incompressible form. The second object is to apply this transformation to the special case of the adiabatic turbulent boundary layer on a smooth wall. The transformation represents at every stage a genuine kinematic and dynamic correspondence between two real flows, both of which are capable of being observed experimentally. Since the mean pressure and mean velocity can then be measured in either flow, the mean acceleration of the fluid can in principle be determined, and the shearing stress can be adequately and accurately defined as the stress which is necessary to account for this acceleration. This formulation leads to a general transformation valid for laminar or turbulent flow in wakes and boundary layers, without regard to the state or energy equations or the viscosity law for the compressible fluid, and without regard to the boundary conditions on surface pressure or temperature in the event that a surface is involved. (Author).




Boundary-layer Theory


Book Description

This text is the translation and revision of Schlichting's classic text in boundary layer theory. The main areas covered are laws of motion for a viscous fluid, laminar boundary layers, transition and turbulence, and turbulent boundary layers.