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Despite over fifty years of research on shock wave boundary layer effects and interactions, many related technical issues continue to be controversial and debated. The present survey provides an overview of the present state of knowledge on such effects and interactions, including discussions of: (i) general features of shock wave interactions, (ii) test section configurations for investigation of shock wave boundary layer interactions, (iii) origins and sources of unsteadiness associated with the interaction region, (iv) interactions which included thermal transport and convective heat transfer, and (v) shock wave interaction control investigations. Of particular interest are origins and sources of low-frequency, large-scale shock wave unsteadiness, flow physics of shock wave boundary layer interactions, and overall structure of different types of interactions. Information is also provided in regard to shock wave investigations, where heat transfer and thermal transport were important. Also considered are investigations of shock wave interaction control strategies, which overall, indicate that no single shock wave control strategy is available, which may be successfully applied to different shock wave arrangements, over a wide range of Mach numbers. Overall, the survey highlights the need for additional understanding of fundamental transport mechanisms, as related to shock waves, which are applicable to turbomachinery, aerospace, and aeronautical academic disciplines.

Unsteady flow characteristics of a normal shock wave, a lambda foot, and a separated turbulent boundary layer are investigated within a unique test section with supersonic inlet flow. The supersonic wind tunnel facility, containing this test section, provides a Mach number of approximately 1.54 at the test section entrance. Digitized shadowgraph flow visualization data are employed to visualize shock wave structure within the test section. These data are analyzed to determine shock wave unsteadiness characteristics, including grayscale spectral energy variations with frequency, as well as time and space correlations, which give coherence and time lag properties associated with perturbations associated with different flow regions. Results illustrate the complexity and unsteadiness of shock-wave-boundary-layer-interactions, including event frequencies from grayscale spectral energy distributions determined using a Lagrangian approach applied to shock wave location, and by grayscale spectral energy distributions determined using ensemble-averaging applied to multiple closely-located stationary pixel locations. Auto-correlation function results and two-point correlation functions (in the form of magnitude squared coherence) quantify the time-scales of periodic events, as well as the coherence of flow perturbations associated with different locations, over a range of frequencies. Associated time lag data provide information on the originating location of perturbation events, as well as the propagation direction and event sequence associated with different flow locations. Additional insight into spatial variations of time lag and flow coherence is provided by application of magnitude squared coherence analysis to multiple locations, relative to a single location associated with the normal shock wave.

Turbulent air flows within a channel with angled rib turbulators (45 degrees) on one wall are numerically predicted using the numerical code ANSYS CFX with a Shear-stress transport (SST) κ-ω turbulence model, and a hexahedral grid with 7115346 cells and no wall function. Three-dimensional turbulent transport, and detailed flow structural characteristics are considered to provide new insight into the mechanisms which result in surface heat transfer augmentations. Time-averaged turbulent flow characteristics and surface Nusselt number distributions are presented for an inlet turbulence intensity level of 1.0 percent, and for Reynolds numbers based upon channel height of 18300 and 48000. Overall, the numerically-predicted results show that large-scale, secondary flow induces a collection of small-scale vortical flows in the channel, as a result of local interactions with individual rib turbulators. These are often associated with different sized and highly skewed vortex pairs, which also induce secondary advection and increased turbulent mixing near ribbed channel surfaces. Within the flow separation regions, just downstream of each rib, surface Nusselt number ratios which are locally lower than for other surface locations, and local secondary flows are generally and partially characterized as upwash flows, with large positive magnitudes of spanwise vorticity, large static pressure deficits, and large static pressure augmentation regions. As the shear layers (initially located above the recirculation zones) impinge onto the test surface, increased mixing develops, as well as local thinning of the reattaching boundary layers, which lead to local Nusselt numbers which are generally higher than for other locations along the test surface.

Considered are interactive relationships between a normal shock wave and the downstream shock wave leg of the associated lambda foot, as well as between a normal shock wave and time-varying static pressure as measured along the bottom surface of the test section. Such relationships are investigated as they vary with two different magnitudes of inlet unsteady Mach wave intensity and are characterized using shadowgraph flow visualization data, as well as power spectral density, magnitude-squared coherence, and time lag data. Employed for the investigation is a specialty test section with an inlet Mach number of 1.54, as utilized within a transonic/supersonic wind tunnel. The resulting data provide evidence of distinct interactions over a wide range of frequencies between the normal shock wave and the downstream shock wave leg of the lambda foot for low inlet unsteady Mach wave intensity. Note that these are not present in the same form and over the same ranges of frequency with high inlet unsteady Mach wave intensity. These differences are partially due to the location where flow events originate. The most significant sources of flow unsteadiness within the present investigation are mostly associated with the normal and oblique shock waves (with low inlet unsteady Mach wave intensity), and mostly with inlet flow disturbances from unsteady Mach waves (with high inlet unsteady Mach wave intensity). The present experimental results additionally evidence important connections between the normal shock wave and unsteady flow events within lower portions of the lambda foot, especially near the adjacent boundary layer separation region.

A variety of different types of vortices and vortex structures have important influences on thermal protection, heat transfer augmentation, and cooling performance of impingement cooling, effusion cooling, and cross flow cooling. Of particular interest are horseshoe vortices, which form around the upstream portions of effusion coolant concentrations just after they exit individual holes, hairpin vortices, which develop nearby and adjacent to effusion coolant trajectories, and Kelvin-Helmholtz vortices which form within the shear layers that form around each impingement cooling jet. The influences of these different vortex structures are described as they affect and alter the thermal performance of effusion cooling, impingement cooling, and cross flow cooling, as applied to a double wall configuration.

The effects of dimples in altering time-averaged flow behavior occur mostly within one-half of one dimple print diameter from the surface, and the dimples within the arrays periodically eject a primary vortex pair from each dimple, which exists in conjunction with edge vortex pairs that form along the spanwise edges of staggered dimples regardless of three dimple depths. As the dimple depth increases, deeper dimples eject stronger primary vortex pairs, with hig her levels of turbulence transport due to larger deficits of time-averaged, normalized total pressure and streamw ise velocity as the surfaces with deeper dimples are approached. Primary vortex pair ejection frequencies range about 7–9 Hz, and edge vortex pair oscillation frequencies range about 5–7 Hz forReH=20,000, regardless of dimple depths.

Considered are interactive relationships between a normal shock wave and the downstream shock wave leg of the associated lambda foot, as well as between a normal shock wave and time-varying static pressure as measured along the bottom surface of the test section. Such relationships are investigated as they vary with two different magnitudes of inlet unsteady Mach wave intensity and are characterized using shadowgraph flow visualization data, as well as power spectral density, magnitude-squared coherence, and time lag data. Employed for the investigation is a specialty test section with an inlet Mach number of 1.54, as utilized within a transonic/supersonic wind tunnel. The resulting data provide evidence of distinct interactions over a wide range of frequencies between the normal shock wave and the downstream shock wave leg of the lambda foot for low inlet unsteady Mach wave intensity. Note that these are not present in the same form and over the same ranges of frequency with high inlet unsteady Mach wave intensity. These differences are partially due to the location where flow events originate. The most significant sources of flow unsteadiness within the present investigation are mostly associated with the normal and oblique shock waves (with low inlet unsteady Mach wave intensity), and mostly with inlet flow disturbances from unsteady Mach waves (with high inlet unsteady Mach wave intensity). The present experimental results additionally evidence important connections between the normal shock wave and unsteady flow events within lower portions of the lambda foot, especially near the adjacent boundary layer separation region.

The effects of dimples in altering time-averaged flow behavior occur mostly within one-half of one dimple print diameter from the surface, and the dimples within the mays periodically eject a primary vortex pair from each dimple, which exists in conjunction with edge vortek pairs that form along the spanwise edges of staggered dimples regardless of three dimple depths. As the dimple depth increases, deeper dimples eject stronger primary vortex pairs, with big her levels of turbulence transport due to larger deficits of time-averaged, normalized total pressure and streamwise velocity as the surfaces with deeper dimples are approached. Primary vortek pair ejection frequencies range about 7-9 Hz, and edge vortek pair oscillation frequencies range about 5-7 Hz for $Re_H=20,000$, regardless of dimple depths.