Calculation Of Boundary-layer Flows Research Articles

The effect of the cone rotation in the supersonic gas flow on the velocity propagation of perturbations in the boundary layer

The paper aimed at studying the peculiarities of boundary layer on a rotating body. Rotation of axisymmetric bodies is often used for their stabilization at a high velocity motion in the atmosphere. Presented are calculation of boundary layer flow on a rotating cone at zero angle of attack. Longitudinal and full enthalpy profiles in the laminar boundary layer obtained as a result of calculations were used to determine upstream disturbances propagation velocity. New integral relation was determined to find out disturbances propagation velocity for the regime of weak hypersonic viscous-inviscid interaction. Effects of surface rotation velocity along with the temperature factor influence were investigated.

The Aerodynamic Mixing Effect of Discrete Cooling Jets With Mainstream Flow on a Highly Loaded Turbine Blade

For the application of film cooling to turbine blades, experimental investigations were performed on the mixing processes in the near-hole region with a row of holes on the suction suction side of a turbine cascade. Data were obtained using pneumatic probes, pressure tappings, and a three-dimensional subminiature hot-wire probe, as well as surface flow visualization techniques. It was found that at low blowing rates, a cooling jet behaves very much like a normal obstacle and the mixing mainly takes place in the boundary layer. With increasing blowing rates, the jet penetrates deeper into the mainstream. The variation of the turbulence level at the inlet of the turbine cascade and the Reynolds number showed a strong influence on the mixing behavior. The kidney-shaped vortex and as an important achievement the individual horseshoe vortex of each single jet were detected and their exact positions were obtained. This way it was found that the position of the horseshoe vortex is strongly dependent on the blowing rate and this influences the aerodynamic mixing mechanisms. A two-dimensional code for the calculation of boundary layer flows called GRAFTUS was used; however, the comparison with the measurements showed only limited agreement for cascade flow with blowing due to the strong three-dimensional flow pattern.

Essential Ingredients for the Computation of Steady and Unsteady Blade Boundary Layers

Two methods are described for calculating pressure distributions and boundary layers on blades subjected to low Reynolds numbers and ramp-type motion. The first is based on an interactive scheme in which the inviscid flow is computed by a panel method and the boundary layer flow by an inverse method that makes use of the Hilbert integral to couple the solutions of the inviscid and viscous flow equations. The second method is based on the solution of the compressible Navier–Stokes equations with an embedded grid technique that permits accurate calculation of boundary layer flows. Studies for the Eppler-387 and NACA-0012 airfoils indicate that both methods can be used to calculate the behavior of unsteady blade boundary layers at low Reynolds numbers provided that the location of transition is computed with the en method and the transitional region is modeled properly.