The design of a novel micro‐screw pump for viscous fluid is described. The device consists of a rotating screw in the centre of the channel, connected with a shaft and micro motor. The objective of this research is to investigate the effect of using various screw geometries on the pump performance. Theoretical analysis by finite volume simulations is carried out to study the influence of pitch, diameter of the screw and the thread (flight depth) to evaluate the optimal dimensions for the pump and to obtain the maximum flow rate. When the screw rotates, a net force is transferred to the fluid due to the differential pressure on the depth of the thread and pressure gradient along the screw axis, thus causing the fluid to displace. The three‐dimensional simulations indicate a gradual increase of the average velocity with increasing the screw diameter. The maximum average velocity can be obtained when the ratio between the pitch and screw diameter (pi/d) is 0.6. Effective pumping is achieved by increasing the thread and pitch at maximum screw diameter. The numerical simulation has been validated experimentally.
This work summarizes the results of the CFD analyses to investigate the effect of the geometrical parameters for a typical coverplate-disk cavity and blade broach system also known as the blade cooling flow supply system. A turbofan high pressure turbine was used as the test vehicle for this investigation. The main objective was to explore potential improvements in engine SFC (aerodynamic performance) by reducing the parasitic work while minimizing the impact on the factors that affect the durability of the turbine blades; feed pressure, temperature, and mass flow. Various tangential on-board injection (TOBI) blade cooling flow supply systems were considered: i) Phase 1 compared the radial TOBI and axial TOBI, ii) Phase 2 compared coverplate-disk cavity shapes, and iii) Phase 3 compared blade broach shapes. The in-house CFD code NS3D was used for the analyses. Compared to the radial TOBI, the axial TOBI has a positive impact on the parasitic work (lower) and blade feed temperature (lower) while it has a negative impact on the blade feed pressure (lower). Further, the coverplate-disk cavity shapes investigated had no significant impact on the parasitic work, blade feed pressure, and blade feed temperature. The CFD solutions show that the major portion of the parasitic work is due to flow turning at the broach entrance. Finally, reducing the blade broach cross-section by sloping up the lower wall has no significant impact on the parasitic work and blade feed temperature but a negative impact on the blade feed pressure and mass flow. Modifying the broach pressure side wall shape is preferred among the blade broach geometries investigated. Future work to improve the CFD analysis consists of performing unsteady analyses to better capture the vortex flow in the blade broach, and including upstream stationary components with either iterative boundary condition modeling or an unsteady multi-stage approach.
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