The current study focuses on numerical investigation of narrow passage flows with pin fin arrays. Six different turbulence models, including linear eddy viscosity models, an explicit algebraic Reynolds stress model, and a V2f model, are explored as they are utilized with k-ε and k-ω platforms. The main objective of the work is to study numerical performance and accuracy of models when applied in the simulation of blade pin fin arrays. The main objective is comparison of the numerical accuracy of models, when applied for the simulation of complex flows within narrow passages. Numerical results obtained with the different models are compared to the experimental data from the literature. As such, comparisons are performed of different flow field quantities, including mean velocity components, Reynolds stress tensor components, and surface Nusselt number distributions.

New experimental data are provided for full-coverage effusion cooling and impingement array cooling, as applied simultaneously onto the respective external and internal surfaces of a single instrumented test plate. For the effusion cooled surface, presented are spatially resolved distributions of surface adiabatic film cooling effectiveness, and surface heat transfer coefficients. For the impingement cooled surface, presented are spatially resolved distributions of surface Nusselt numbers. Impingement jet arrays at different jet Reynolds numbers, from 7930 to 18,000, are employed. Experimental data are given for spanwise and streamwise impingement hole spacing such that coolant jet hole centerlines are located midway between individual effusion hole entrances. For the effusion cooling, streamwise hole spacing and spanwise hole spacing (normalized by effusion hole diameter) are 15 and 4, respectively. Effusion hole angle is 25 deg, and effusion plate thickness is 3.0 effusion hole diameters. In regard to the impingement cooled cold-side surface of the effusion plate, associated surface Nusselt number variations provide evidence that impingement jets are turned and redirected as they cross the impingement passage, just prior to the entrance of coolant into individual effusion holes. In regard to the effusion cooled hot-side surface of the effusion plate, when compared at particular values of injectant and mainstream Reynolds numbers, streamwise location x/d_e and blowing ratio BR, significantly increased thermal protection is provided when the effusion coolant is provided by an array of impingement cooling jets (compared to a cross flow channel supply arrangement).

In the present study, hydrophobic roughness is used to induce near-wall slip in a single rotating-disk micropump operating with Newtonian water. The amount of induced slip is altered by employing different sizes of surface roughness on the rotating disk. The magnitudes of slip length and slip velocities increase as the average size of the surface roughness becomes larger. In the present study, increased slip magnitudes from roughness are then associated with reduced pressure rise through the pump and lower radial-line-averaged shear stress magnitudes (determined within slip planes). Such shear stress and pressure rise variations are similar to those which would be present if the slip is induced by the intermolecular interactions which are associated with near-wall microscale effects. The present slip-roughness effects are quantified experimentally over rotational speeds from 50 to 1200 rpm, pressure increases from 0 to 312 kPa, net flow rates of $0–100\mu \text{l}/\text{min}$ , and fluid chamber heights from 6.85 to $29.2\mu \text{m}$ . Verification is provided by comparisons with analytic results determined from the rotating Couette flow forms of the Navier–Stokes equations, with different disk rotational speeds, disk roughness levels, and fluid chamber heights. These data show that slip length magnitudes show significant dependence on radial-line-averaged shear stress for average disk roughness heights of 404 and 770 nm. These slip length data additionally show a high degree of organization when normalized using by either the average roughness height or the fluid chamber height. For the latter case, such behavior provides evidence that the flow over a significant portion of the passage height is affected by the roughness, and near-wall slip velocities, especially when the average roughness height amounts to 11% of the $h=6.86\mu \text{m}$ passage height of the channel. Such scaling of the disk slip length $b_{\text{disk}}$ with fluid chamber height $h$ is consistent with d-type roughness scaling in macroscale flows.