In the present work, the impact of suction and its related parameters, including dimensionless suction velocity, suction angle, and suction length, on controlling the flow over a NACA 0012 airfoil with a Gurney flap have been numerically investigated. The height of the gurney flap is 2% of the cord. The Reynolds number of the flow is 2.1 × 106, which is entirely turbulent. Turbulent flow has been analyzed using the Reynolds stress model (RSM). The suction on the airfoil is modeled as uniform and normal (vertical suction), and the length of the suction area is 3% of the chord length (CHL) (3cm). The suction jet is designed at two angles of 60 and 90 degrees. The results indicate that with the rise of the suction dimensionless velocity, the drag coefficient (CD) decreases. The maximum ratio of forward to backward dimensionless velocity due to suction is one, occurring at a position 2.5% of the chord length (CHL). This indicates that for optimal performance, the jet suction on the airfoil should be positioned at 2.5% of the CHL. The results of this study contribute to the development of a novel method for Boundary layer (BL) control, aiming to optimize drag force on airfoils for improved flow management.

Supersonic flow over a tapered body of revolution has been investigated both experimentally and numerically. The experimental study consisted of a series of wind tunnel tests on an ogive-cylinder body. Static pressure distributions on the body surfaces at several longitudinal cross sections, as well as the Boundary layer profiles at various angles of attack have been measured. Further, the flow around the model was visualized using Schlieren technique. Tests with a natural development of the Boundary layer and with tripping were also carried out. All tests were conducted in the trisonic wind tunnel of Qadr Research Center. Our results show that artificial Boundary layer tripping has minor effect on the static surface pressure distribution (depending on its diameter and installation location), while the changes in total pressure around the body were significant. Tripping the Boundary layer increased its thickness, changed its profile particularly near the body surface. Two oblique shock waves were formed in the front and behind the trip wire. In this study, using multi-block grid, the thin layer Navier-Stokes (TLNS) equations were solved around the above models. Also patched method was used near the interfaces. Good agreements were achieved when the numerical results were compared with the corresponding experimental data.

Both experiments and computations are performed and analyzed to investigate the effectiveness and mechanisms of different slotted aspiration schemes in controlling the separated flows in a highly-loaded axial compressor cascade. It is found that the Boundary layer aspiration on the blade suction surface can improve the incidence characteristics of the airfoil within most of the incidence range except of the extremely high incidence and the profile loss coefficient is reduced remarkably as the aspirated massflow increases. The combined aspiration is the most effective scheme to control both the separated flow on the blade suction surface and the three-dimentional hub corner separation, and an improper design of aspiration would lead to a deterioration of the flow field. Different aspiration schemes have different effectiveness in controlling the flow separation, which leads to various influences on the blade loading and the diffusion abilities. The cascade incidence characteristics of different aspiration schemes show that the part-span aspiration scheme (SS1) located on the blade suction surface can only improve the overall flow field in very high incidences, while the other schemes can reduce the overall loss coefficient within almost the whole incidence range, especially for the combined aspiration scheme. There always exists a closed separation in the cascade when the Boundary layer separation is not removed completely on the blade suction surface and in the hub corner. In addition, the type of critical point is affected by the spanwise static pressure gradient, which has significant effects on the cascade performance.