This report documents the experimental study for four different three-dimensional turbulent flows. The investigation focuses on near wall measurements in these flows. Several experimental techniques are used in the studies; however, the bulk of the investigation focuses on a three-orthogonal-velocity-component fiber-optic laser Doppler anemometer (3D-LDA) system. The control volume of the 3D-LDA is on the order of 50 micro-meter in size, or a y+ distance of around 2.3 units (using average values of U? and? from the experiment). An auxiliary small boundary layer wind tunnel (auxiliary tunnel) and a low speed linear compressor cascade wind tunnel (cascade tunnel) are utilized in this study. One of four flow experiments is done in the auxiliary tunnel the other three are in the cascade tunnel. The first three-dimensional turbulent flow is a vortical flow created by two half-delta wing vortex generators. Near wall secondary flow features are found. The second flow is an investigation of the first quarter chord tip gap flow in the cascade tunnel. Strong three-dimensional phenomena are found. The third flow investigated is the inflow to the compressor cascade with the moving wall. The experiment records shear layer interaction between the upstream flow and moving wall. Finally the fourth flow investigated is the inflow to the compressor cascade with the moving wall with half-delta wing vortex generators attached. Phase-averaged data reveal asymmetrical vortex structures just downstream of thevortex generators. This is the first time any near wall data has been taken on any of these flows.

An experimental investigation was conducted at selected locations of the near-wall region of a three-dimensional turbulent air boundary layer relaxing in a nominally zero external pressure gradient behind a transverse hump (in the form of a 30 degree swept, 5-foot chord wing-type model) faired into the side wall of a low speed wind tunnel. Wall shear stresses measured with a flush-mounted hot-film gage and a sublayer fence were in very good agreement with experimental data obtained with two Preston probes. With the upstream unit Reynolds number held constant at 325000/ft approximately one-fourth of the boundary layer thickness adjacent to the wall was surveyed with a single rotated hot-wire probe mounted on a specially designed minimum interference traverse mechanism. The boundary layer (approximately 3.5 in. thick near the first survey station where the length Reynolds number was 5500000) had a maximum crossflow velocity ratio of 0.145 and a maximum crossflow angle of 21.875 degrees close to the wall. The hot-wire data indicated, in agreement with the findings elsewhere, that the apparent dimensionless velocity profiles in the viscous sublayer region are universal and that the wall influence is negligible beyond y(+) =5. The existence of wall similarity in the relaxing flow field was confirmed in the form of a log law based on the resultant mean velocity and resultant friction velocity (obtained from measured skin friction).

In order to improve predictions of flow behavior in numerous applications there is a great need to understand the physics of three-dimensional turbulent boundary layers, dominated by near-wall behavior. To that end, an experiment was performed to measure near-wall velocity and Reynolds stress profiles in a pressure-driven three-dimensional turbulent boundary layer. The flow was achieved by placing a 30 deg wedge in a straight duct in a wind tunnel, with-additional pressure gradient control above the test surface. An initially two-dimensional boundary layer (Re approx. equal 4000) was exposed to a strong spanwise pressure gradient. At the furthest downstream measurement locations there was also a fairly strong favorable pressure gradient. Measurements were made using a specially-designed near-wall laser Doppler anemometer (LDA), in addition to conventional methods. The LDA used short focal length optics, a mirror probe suspended in the flow, and side-scatter collection to achieve a nearly spherical measuring volume approximately 35 microns in diameter. Good agreement with previous two-dimensional boundary layer data was achieved. The three-dimensional turbulent boundary layer data presented include mean velocity measurements and Reynolds stresses, all extending well below y(+) = 10, at several profile locations. Terms of the Reynolds stress transport equations are calculated at two profile locations. The mean flow is nearly collateral at the wall. Turbulent kinetic energy is mildly suppressed in the near-wall region and the shear stress components are strongly affected by three-dimensionality. As a result, the ratio of shear stress to turbulent kinetic energy is suppressed throughout most of the boundary layer. The angles of stress and strain are misaligned, except very near the wall (around y(+) = 10) where the angles nearly coincide with the mean flow angle.

The various methods for measurement of the six components of the turbulence stress tensor are reviewed, and some of the data on the turbulent shear stress vector are presented to demonstrate the validity of current ideas for.

An analytical approach toward numerical calculation of the three-dimensional turbulent boundary layer on a sharp cone at incidence under supersonic and hypersonic flow conditions is presented. The theoretical model is based on implicit finite-difference integration of the governing three-dimensional turbulent boundary-layer equations in conjunction with a three-dimensional scalar eddy-viscosity model of turbulence. Comparison is made of present theory with detailed experimental measurements of the three-dimensional turbulent boundary-layer structure (velocity and temperature profiles), the surface streamline direction (obtained via an oil-flow technique) and surface heat-transfer rate.

The IUTAM Symposium on Three-dimensional Turbulent Boundary Layers was suggested by the Gesellschaft für Angewandte Mathe­ matik (GAMM) and sponsored by the International Union of theor­ etical and Applied Mechanics. The symposium was organized by H.H. Fernholz (Hermann-Föttinger-Institut für Thermo- und Fluiddynamik der Technischen Universität Berlin) and E. Krause (Aerodynamisches Institut der RWTH Aachen). After two success­ ful Euromech Colloquia on the same topic in Berlin 1972 and Trondheim 1975 the organizers felt that another meeting should be convened, this time with participants from inside and out­ side Europe. The aim of the symposium has been to bring together scientists who are actively engaged in boundary layer research, both ex­ perimental and theoretical. The scope of the meeting encompass­ ed incompressible and compressible three-dimensional turbulent boundary layers. Special emphasis was laid on economical cal­ culation methods, on measurements of fluctuating quantities and on measuring techniques designed for and applied success­ fully to three-dimensional boundary layers. From among thirty-four papers submitted for presentation, twenty­ six contributions of twenty-five minutes each were selected by the European mernbers of the Scientific Committee. Furthermore there were four invited lectures of forty-five minutes. Short discussions were held directly after each presentation with a long discussion period at the end of each day. The final dis­ cussion on the last day of the symposium was recorded on tape and is presented in a slightly shortened version as the last contribution in this volume.