Vortex Shedding from a Ground Tracking Radar Antenna and its 3D Tip Flow Characteristics

Abstract: High-speed ground tracking radar systems rotating at about 60 rpm are currently being implemented as modern air traffic control systems in airports. The flow induced vibration and noise generation of the newly developed radar antennas are the two serious problems that jeopardize the successful deployment of the new ground aircraft tracking systems. This paper deals with the viscous flow details of the highly three-dimensional antenna tip section and the vortex shedding characteristics at Re=426,000. The current analysis uses a 3D computational approach for the computation of viscous flow details with the highly 3 D tip geometry. A 2D unsteady computation of the vortex shedding phenomena is also presented. This paper is a continuation of the computational study dealing with the determination of aerodynamic drag coefficients on ASDE-X (Advanced Surface Detection Equipment) antenna cross sections previously presented in Gumusel et al. [1]

CONJUGATE HEAT TRANSFER ANALYSIS OF INTERNALLY COOLED TURBINE BLADE

There are different characters of air flow in a conventional gas turbine blade cooling channel. These flow characters; including high streamline curvature caused from 180 degree bends, sequential flow separations caused from rib turbulators and pin-fin structures are analyzed separately with available commercial software for different turbulence models and validated against reliable experimental data from open literature. Also coupled conjugate heat transfer analyses on NASA C3X vane, which has only radial holes through blade span for cooling, are conducted with the same turbulence models. The accuracy information gathered from all these analyses; each interested with a single character of air and coupled conjugate heat transfer are put together and applied to a conjugate numerical analysis of internally cooled (VKI) LS-89 turbine blade. Internal cooling scheme which is applied to (VKI) LS-89 turbine blade encompassed the aforementioned flow characters and analyses are performed under realistic conditions. Because of the high temperature values occurring at realistic conditions, thermal conductivity and specific heat capacity of air and metal (Inconel 718) are modeled as temperature dependent material properties instead of using constant values. Conducted research revealed that 4 eqn. V2-f turbulence model gives similar results compared to the 2 eqn. Realizable k-e, k-w SST turbulence models for 180 degree bend and rib turbulator cases. However, at NASA C3X vane analyses V2-f turbulence model results are far more accurate than other two turbulence models in the manner of heat transfer coefficient and surface temperature distribution