CFD simulation of gas turbine ventilation and gas dilution

Abstract: Gas turbine engines are one of the primary sources of electricity currently in the world. The assembly consists of multiple subsystems all of which are placed within an acoustic enclosure. Dilution ventilation is a widely used and recommended means of protection against the risk of explosion within gas turbine acoustic enclosures. Leakage and accumulation of flammable gas and its ignition from the turbine are one of the reasons for this explosion. The ISO regulations provide a safety criterion for the allowable size of flammable gas cloud as a proportion of enclosure volume. The effectiveness of the ventilation system in maintaining the clouds and the optimum placement of gas detectors to detect these clouds is determined through CFD simulations. This thesis deals with the primary step in the process of detecting the problematic regions which might allow the growth of the gas clouds to pass safety levels if the engine is not shut down. Using the same methodology, other possible configurations of the ventilation system and the effect on the flow due to the addition of a platform and movement of junction boxes are also studied. It is found out that the configuration where the inlet and outlets of the standard configuration are interchanged is arguably the best followed by the configuration with a split inlet, standard configuration, and lastly, the one with reduced volumetric flow rate. The platform and the movement of junction boxes across the walkway/platform do not affect the flow in any significant manner. The vertical movement of junction boxes affect the size of the low-speed region behind the inlet plenum. The thesis satisfied its objectives and provides a guideline for the same.