Manoj Prakash Gokhale

SFC Benefit With Split Injection in Two-Stroke Diesel Engine

The influence of split-injection on engine performance is studied using system and in-cylinder simulation of a two-stroke medium speed diesel engine. System level models for the engine and fuel system and a multi-dimension CFD model for the combustion chamber were developed and calibrated with experimental data. Calibration of these models from the available test data is discussed and calibration results are presented. The SFC and NOx predictions show good sensitivity to injection timing variation. These calibrated models were then used to simulate split injection through the modification of the fuel injector. Split injection achieved through this modification results in fuel savings while maintaining same NOx levels.Copyright

Integration of System and Detailed CFD Models for IC Engine Applications

Stringent IC engine tailpipe emission regulations are being enforced worldwide. To meet the emission norms various emission reduction strategies are explored in conjunction with the fuel consumption improvements. To achieve these goals, modeling of engine system for combustion and emission plays a major role in minimizing the development cost and time. The successful application of combustion and emission modeling depends on the response, accuracy and run-time of the models being used. System level models are generally used to study and optimize the full IC engine system. These models have low runtime (2–10 mins) but are limited in their ability to describe and respond to the geometry and physics of complex fluid dynamics, combustion and emissions. Detailed CFD models are used for these areas but have long runtimes (8–40 hours). The procedure for developing and calibrating commercially available system and in-cylinder CFD software models are explained. Also the integration of these models to minimize the overall runtimes is described in detail.Copyright

Cooling Enhancement of Radiators Using Dimples and Delta Winglets

Cooled exhaust gas recirculation and lower intake manifold temperature (post compressor) are used to meet emission regulations for a turbocharged intercooled diesel engine. This places a significant demand on the cooling load and space constraint on the radiator of the engine. A typical radiator is a cross-flow fin-tube heat exchanger with coolant water flowing inside the tube and ambient air taking out heat from the fin and tube surfaces. The major resistance to heat transfer in this configuration is offered by the air-side heat transfer co-efficient. The current study focuses on enhancing convective cooling rates on air side in a typical radiator which helps in taking additional load of EGR cooling with minimal increase in space and radiator fan power. Published literature clearly indicates that specific geometrical structures such as delta winglets and dimples, when placed in a convective flow path, act as vortex generators. This ability helps in disturbing/disrupting a steady thermal boundary layer, resulting in enhanced convective heat transfer. Detailed CFD simulations have been carried out to study the individual and combined effect of dimples and delta winglets on the heat transfer rates in a typical radiator geometry. Delta winglets on the fins indicated significant heat transfer enhancement but with increased pressure drop. Dimples on the tubes also led to enhanced heat transfer rates, but with a comparatively lesser increase in the pressure drop. A combination of delta winglets on the fins and dimples on the tubes increased the heat transfer rates substantially (+40%) with a minimal increase in pressure drop compared to the baseline case.Copyright