Attaining the design point of any mechanism necessitates undergoing the initial processes satisfactorily. Gas turbine engines used on land, air and water also undergo the initial starting process with the help of external sources. A typical operation cycle of a gas turbine engine consists of zero to idle speed, idle to max speed and max speed to full reheat, the latter being the case for military engine application. It is found that gas turbine engine performance prediction has improved with the usage of computers where the physics of engine behaviour are mathematically coded. The performance prediction software also helps in designing the control systems which governs the engine response to throttle inputs, define the safe operational limits and provide a trouble free automated engine operation during the entire mission. This paper gives an overview of the experimental research work undertaken on compressor and combustor components and engine to improve upon the starting phenomenon since 1950s. The review also looks into the theoretical work undertaken to model the starting process that may help reducing the expensive and time-consuming testing of developmental engine.

Performance of intake duct with fixed inlet trajectory and different area distributions have been analyzed using a commercial CFD (Computational Fluid Dynamics) software. The performance have been evaluated for fixed boundary conditions. The area distributions studied are defined by varying cross sectional area at different locations of intake duct by keeping the inlet and exit area same. The performance of the intake ducts are studied in terms of the pressure recovery coefficient, total pressure loss, pressure recovery factor and distortion coefficient in the present work. The motion caused by the change in centerline curvature is analyzed. The objective of the work is to derive a shape of the duct with minimum distortion of the flow and maximum pressure recovery.