Search Results

The automotive industry in world is facing the problem of reduction of emissions coming out of the engine. Also, the stringent emission norms imposed by the regulating body for transition from BS IV to BS VI urges the auto makers to concentrate on new technologies to reduce the emissions. One of the major emissions coming out of the diesel engine is oxides of nitrogen (NOx) which is detrimental to human health. This NOx emission is formed when the combustion temperature of engine exceeds the threshold limit. There are several methods available to reduce these NOx emissions formed in-cylinder. Exhaust Gas Recirculation (EGR) is one such system, which reduces the NOx emission formed inside the engine by supplying a portion of the exhaust gases. By re-circulating exhaust gases, the air admitted to the engine is diluted. Further, due to the high latent heat of vaporization of water, water vapor tends to absorb more amount of heat that is generated during combustion.

In India, for two-wheeler application, carburettor is the preferred fuel supply system for majority of the market, owing to its simplicity and low cost. With the regulations becoming stringent, carburettor internal structure requires modification. One of the important parameters is the venturi shape, which controls the air-fuel mixture supply to the engine. Venturi shape plays an important role in deciding the transient performance characteristics. In this study, a CFD analysis has been carried out to predict the pressure and velocity at the venture of the carburettor. Four different cross sections namely, circular, oval, trapezoidal and double D venturi shapes were selected. The geometric model of the carburettor was created and mesh refinements were carried out in critical regions. At part open throttle, CFD prediction of airflow rate with Trapezoidal venturi shape was found higher when compared to other venturi shapes.