الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
The main parts of the gas turbine engine are the compressor, combustor, turbine, and control units. Sometimes the gas turbine engine encounters a problem in the control unit that can badly affect the engine’s performance at different operating regimes. Consequently, a drastic decrease in engine life time and reliability is noticed. The main affecting parameters are the air control system, combustion, and compression systems of the gas turbine engine. Therefore, the air flow control system is one of the important parameters that affect the gas turbine engine’s dynamic performance. So, the dynamic performance of the engine air control system has to be investigated. Controlling the dynamic performance of the engine air control system relies; heavily on electro hydraulic systems. Among the most common and challenging problems with Electro-Hydraulic control systems is investigating the effect of changing the design geometry, including shapes, of their components.
This thesis presents a spool in an Electro-Hydraulic Servo Valve (EHSV) in a turbo shaft engine as an example. A detailed analysis of a fuel-based position control device is presented. To assess the implications of shape modifications on the dynamic performance of the system behaviour, three distinct shapes for this spool were presented. ANSYS FLUENT 19.2 is used for modelling and CFD study of the three shapes of the spool at four different openings is presented. The outcomes were compared with each other.
The results showed that using a three-step spool is a better design and selection than using one or two steps. There was a reduction in pressure bumps [38 – 55 %, as shown in Fig. 4.3, 32 %, as shown in Fig. 4.5, and 8.4 %, as shown in Fig. 4.7] and a smoothing of the velocity of the fluid inside the valve [96 %, as shown in Fig. 4.4, 96.6 %, as shown in Fig. 4.6, and 76.7 %, as shown in Fig. 4.8]. So, the dynamic performance of the valve will be improved by reducing the pressure bumps and reducing the jet of fluid flow at the valve inlet, vortices, and smoothness in the moving spool. Also, the performance of the IGV will be improved (good air control). As a result, good dynamic performance of the gas turbine will be obtained.
Key words : Servo solenoid valve, Servo valve, Effect of valve spool geometry on valve performance, Position control, Valves, Directional control valves, Spool valve, Inlet guide vane (IGV), Computational fluid dynamics (CFD) .