No abstract

No abstract

This paper investigates the effect of uniform suction on the characteristics of the developing laminar boundary layer about a sphere which is subjected to a steady stream of fluid. The study includes the developing meridional velocity profiles, the separation angle, the wall shear stress and the frictional drag coefficient (C D). Making limitation of suction region on sphere surface leads to reduction in frictional drag. However, it reduces the separation angle (e s) with slight effect. The present regime succeeded in obtaining numerical results up to 180°.

The effect of temperature-dependent viscosity on the flow development behavior inside a circular pipe was studied. The development of centerline axial velocity is presented at different axial positions throughout the tail straight pipe of test section by measurements carried out experimentally using Pitot tube and computed numerically using ANSYS FLUENT 16 software code. The measurements were conducted for various flow rates depending on the control valve opening at two different temperature of fluid 30°c and 60°c. It was found that the computational results showed a good trend agreement with the experimental results. The influence of heat on the density and viscosity of fluid leads to increasing flow rate and Reynolds number. Therefore, it was observed that the hydrodynamic entrance length has been increased due to heating the fluid. The length was increased by 21.4% for the lower flow rate, which is more than the percentage obtained for the higher flow rate. The results also show that the values of centerline velocity for a fully developed region under heated conditions have been changed slightly compared to unheated conditions. Ultimately, a proper placement of the flow measuring device was determined to measure the flow rate accurately.

This paper puts forward hydraulic auto-leveling control system for vehicle-borne platform with four legs based on Programmable Logic Controller. In particular, a Siemens S7-300 (Programmable Logic Controller) PLC, and the accessional hydraulic circuit and control circuit is used. By introducing the theory of auto-leveling, the methods to design the hardware and software of the embedded control system are presented. The system adopts highly accurate two-axis tilt sensor and proportional direction control valves, optimizing auto-leveling strategy. The hardware and software of the embedded system make use of the concept of minimizing the error as possible on tilting axis corresponding to the required accuracy. The tests prove that this auto-leveling control system improves leveling-precision, performance stability of the system, shortens the leveling-time, and satisfies the maneuverability and operating requirements of the vehicle-borne platform in formidable nature conditions.