Bhaskar Tamma

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

Dynamic analysis tool for the design of tubular linear permanent magnet machines

This paper presents an analytical tool for tubular linear permanent magnet (PM) machine design and analysis. This tool provides fast solutions to the system variables of a linear motor, e.g., force, current, voltage, loss, efficiency, etc., while taking into account the dynamic load cycle and movement profile. Extensive validation of the analytical tool has been carried out with results from FEM simulations using the software package Maxwell.

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

Water Addition in Diesel Engine Intake for NOx Reduction: Comparison of Modeling and Experiments

Reduction in emissions, especially NOx has been the main study of various engine researchers in the light of stringent emission norms. To reduce the time and cost involved in testing these technologies, engine thermodynamic cycle predictive tools are used. The present work uses one such predictive tool (GT Power from Gamma Technologies) for predicting the influence of water addition in a turbocharged 6-cylinder diesel engine intake on engine performance and NOx emissions. The experiments for comparison with modeling included the introduction of liquid water in the engine intake stream, between the compressor and intercooler ranging from 0 to 100% of fuel flow rate. NOx emission reduced linearly with water addition with reduction of 63% with less than 1% penalty on fuel efficiency at 100% water addition. The GT Power model predicted the performance within 5% of experimental data and NOx emission within 10% of the experiments.Copyright

Investigation of Injection Pressure Effects on Medium Speed Diesel Engine Emissions

As with most internal combustion engines, the locomotive diesel is subjected to increasingly stringent regulatory emissions standards. Currently, diesel electric freight locomotives are regulated by the Tier 1 emission standards that went into effect January 1, 2002 as ruled by the United States Environmental Protection Agency (EPA). Beginning January 1, 2005 the US EPA Tier 2 diesel locomotive emissions standards will become effective. To achieve the new emissions standards an extensive engine development program was initiated. This paper will present a portion of the development conducted on a single cylinder engine (SCE) investigating the effects of injection pressure on emissions. The experimental results are presented with a discussion of the possible mechanisms leading to the results with supporting evidence from existing literature and analysis. This paper will focus on the effect of injection pressure as generated by pump capacity and nozzle cup hydraulic flow.Copyright