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This paper deals with experimental study of in-cylinder tumble flows in a single-cylinder, four-stroke, two-valve internal combustion engine using a pentroof-offset-bowl piston under non-reacting conditions with four intake manifold orientations at an engine speed of 1000 rev/min., during suction and compression strokes using particle image velocimetry. Two-dimensional in-cylinder tumble flow measurements and analysis are carried out in combustion space on a vertical plane passing through cylinder axis. Ensemble average velocity vectors are used to analyze the tumble flows. Tumble ratio (TR) and average turbulent kinetic energy (TKE) are evaluated and used to characterize the tumble flows. From analysis of results, it is found that at end of compression stroke, 90° intake manifold orientation shows an improvement in TR and TKE compared other intake manifold orientations considered.

In this work a novel mixture injection system has been developed and tested on a two stroke scooter engine. This system admits finely atomized gasoline directly into the combustion chamber. It employs many components that were individually developed, fabricated, tested and then coupled together. A small compressor driven by the engine sends pressurized air at the correct crank angle through a timing valve. This is connected to a mechanical injector through a high pressure pipe. Fuel is metered into the high pressure pipe using a standard low pressure injector. The developed mixture injection system resulted in considerable improvements in thermal efficiency and reduction in HC emissions over the manifold injection method at all engine outputs. A considerable reduction in short circuiting losses was seen. The highest brake thermal efficiency achieved was 25.5% as against 23% with the manifold injection system.

A diesel engine was operated with karanja oil, bio-diesel obtained from karanja oil (BDK) and diesel as pilot fuels while LPG was used as primary fuel. LPG supply was varied from zero to the maximum value that the engine could tolerate. The engine output was kept at different constant levels of 25%, 50%, 75% and 100% of full load. The thermal efficiency improved at high loads. Smoke level was reduced drastically at all loads. CO and HC levels were reduced at full load. There was a slight increase in the NO level. Combustion parameters indicated an increase in the ignition delay. Peak pressure and rate of pressure rise were not unfavorably affected. There was an increase in the peak heat release rate with LPG induction. The amount of LPG that could be tolerated with out knock at full load was 49%, 53% and 61% on energy basis with karanja oil, BDK and diesel as pilots.

Hydraulic brakes are widely used in passenger cars and light commercial vehicles. Rear wheel locking ahead of front wheels creates vehicle instability and is considered most dangerous and illegal. This is prevented by using valves in the brake system and by proper brake component selection. A deceleration proportioning (GP) valve senses the deceleration of the vehicle and modulates the rear brake pressure. The valve under investigation has failed to meet the regulatory requirements of Bureau of Indian Standards (BIS) 11852; hence, the performance of a GP valve was studied experimentally in static and dynamic conditions of the vehicle. It was found that the valve is sensitive to the rate of pedal application. An analytical model was developed to predict the displacement of the ball under different rates of pedal application and at different decelerations.

This paper deals mainly with computer simulation of processes of Gasoline Direct Injection (GDI) associated with Extended Expansion Engine (EEE) concept applied to a four-stroke, single-cylinder SI engine. In the case of standard SI engines, part-load brake thermal efficiencies are low due to higher pumping losses. The pumping losses can be reduced by operating the engine always at full throttle as done in extended expansion engine. In extended expansion engine, higher Geometric Expansion Ratio (GER) compared to Effective Compression Ratio (ECR) is responsible for better performance at part loads. Usually, in this engine, by delaying inlet valve closure timing along with reduced clearance volume, extended expansion is achieved. Experimentally many researchers have proved that variable valve timing and variable compression ratio techniques adopted in SI engines, improves the part- load performance greatly.

The pressure gain characteristics of jet pipe servovalve is required as an input to the designer for improving performance of the servovalve. An attempt has been made to design the first stage jet pipe servovalve parameters to get maximum pressure recovery. The static recovery pressure in receiving holes is a function of jet pipe nozzle displacement relative to receiver plate. The recovery pressure depends on web thickness, jet pipe nozzle diameter, receivers hole diameter, nozzle offset and nozzle stand-of distance. A detailed static recovery pressure analysis of a two stage, four-way, closed ports electrohydraulic flow control valve considering the effect of web thickness, nozzle diameter, receiver hole diameter and offset parameters are presented in the paper. Also the effect of supply pressure on recovery pressure is presented.