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A gas turbine combustion system is an embodiment of all complexities that engineering equipment can have. The flow is three dimensional, swirling, turbulent, two phase and reacting. The design and development of combustors, until recent past, was an art than science. If one takes the route of development through experiments, it is quite time consuming and costly. Compared to the other two components viz., compressor and turbine, the combustion system is not yet completely amenable to mathematical analysis. A gas turbine combustor is both geometrically and fluid dynamically quite complex. The major challenge a combustion engineer faces is the space constraint. As the combustion chamber is sandwiched between compressor and turbine there is a limitation on the available space. The critical design aspect is in facing the aerodynamic challenges with minimum pressure drop. Accurate mathematical analysis of such a system is next to impossible.

In the present work, an attempt was made to study numerically, using CFD, the effect of vane-shape on the flow-field and heat transfer characteristics of a disc brake rotor for different configurations and at different speeds. Initially, the CFD code used in this work was validated by experimental results obtained by conducting experiments on a test rotor using particle image velocimetry (PIV). Further, six types of rotor configurations viz., straight radial vane (SRV), tapered radial vane (TRV), modified tapered radial vane (MTRV), circular pillared (CP), diamond pillared (DP) and modified diamond pillared (MDP) were considered for the numerical analysis. Three of them were radial type and other three were of pillared type rotors. A rotor segment of 20° was considered for the numerical analysis due to rotational symmetry. Validation was done for SRV rotor, for which the experimental and predicted results were in good agreement.

This paper deals mainly with the computer simulation and experimental investigations on a single cylinder, four-stroke, spark ignited, extended expansion engine. The simulation procedure involves thermodynamic and global modeling techniques. Sub-models have been used for predicting heat transfer, friction and gas exchange processes. A two-zone model is adopted for combustion process. Combustion model predicts mass burning rate, ignition delay and combustion duration. It uses sub-models for calculating flame-front area, flamespeed and chemical equilibrium composition of ten product species. Experimentally measured valve-lift data along with suitable coefficient of discharge is used in the analysis of gas exchange process. Unburned hydrocarbons, carbon monoxide and nitric oxide emissions have also been predicted. Experiments have been conducted on a single cylinder, air-cooled, four-stroke, spark-ignition engine.