Keywords: reciprocating engine, piston, additive manufacturing, topological optimization, high-cycle fatigue, efficient distribution of material.

The article is dedicated to piston manufacturing methods taking account of engine boost level. It is shown that geometrically optimal piston may be produced using additive manufacturing technologies. 3-D model of such piston is based on topology optimization (TO) method. The article contains examples of continuous TO applied to reciprocating engine pistons. An alternative TO method is offered based on calculated fatigue safety margin, which enables efficient distribution of piston material in terms of mechanical strength.

Keywords: reciprocating engine, binary cycle, discharge chamber, combustion chamber, free piston, damping air charge.

A schematic layout of reciprocating engine featuring binary cycle is presented. Such engine includes two chambers (combustion chamber and discharge chamber) separated by a free piston. Engine displacement volume is thus divided into two separate chambers, which results in better mixing and lower peak loads exerted to powertrain components, because part of the air charge is compressed in the chamber confined by main piston and free one. The air charge in this configuration acts as oxidant (in the combustion chamber) and, at the same time, as elastic linkage between gas and powertrain components (in the discharge chamber).

Keywords: gas engine, turbocharger type S200G, failure cause analysis, modular bearing, import replacement, stand tests.

A series of experimental investigations targeted at higher reliability of KAMAZ gas engines has been carried out. The reliability analysis revealed sources of Schwitzer S200G turbochargers' failures in the field. Within the framework of import replacement program, S200G turbochargers have been replaced with Russian make turbochargers type ТКР 7С-6, modernized and adapted to gas engine applications. Stand and field tests demonstrated high efficiency and reliability of Russian make turbochargers type ТКР 7С-6, featuring modular bearings and improved oil cleaning system.

Keywords: reciprocating engine, supercharge system, partial load, controllable turbocharger, two-stage sectional turboboost, wastgate, heat recovery.

Core trends in supercharge system optimization as a means to enhance engine low-load efficiency are discussed. Presented are examples of supercharge system optimization in state-of-art engines from world leading engine builders. System optimization methods include use of controllable (in particular, hybrid) turbochargers, gas and air bypass, two-stage sectional turboboost, wastgates and heat recovery.

Keywords: two-stroke dual-fuel marine engine, Otto cycle, fuel system, operating values, propeller curve, engineering-and-economical performance.

Two-stroke dual-fuel engines firing low-pressure natural gas in Otto cycle are able to secure compliance with IMO Tier-3 NOx emissions requirements. The authors offer the results of comparative analysis of engine operation on liquid and gaseous fuel. Computer simulation shows performance trends when the engine (6X72DF built by Winterthur Gas and Diesel Ltd.) follows propeller curve.

Keywords: Wankel engine, hydrocarbon emissions, carbon oxide, hydrogen, gasoline, idling, partial load.

Hydrogen addition as a means to improve environmental performance of type WAZ-311 Wankel engine was investigated in a series of experiments. However attractive might be the idea of hydrogen as a main fuel, its keeping aboard a ship is impractical. Addition of small amount of hydrogen to conventional fuel in order to boost combustion seems more realistic. Wankel engine is more suitable for firing hydrogen than conventional reciprocating engine, since rotary engine is less prone to preignition and backflash. Higher rate of flame propagation due to the presence of free hydrogen results in decrease in emission of incomplete combustion products.

Keywords: engine, shell bearing, tri-metal alloy, polymer coating, oil viscosity, bearing reliability and lifetime

This review covers the papers of the last CIMAC Congress dedicated to perfecting of shell bearings in engine crank train system. Experts of Daidometal Co. Ltd. (Japan) look for optimization of physical and chemical properties of tri-metal (Al–Sn–Si) shell alloy in order to enhance bearing life and fatigue strength. Engineers of Miba Bearing Group (Austria) studied factors affecting lifetime and reliability of bearings in engines that power vehicles whose application involves frequent start-stop events. It is noted that current trend towards reduced oil viscosity is reducing the hydrodynamic friction significantly, but also leads to an increasing share of mixed friction running conditions, and, consequently, probability of failure. This may be avoided through use of special polymer coatings and dry lubricants. The CIMAC papers are translated into Russian by G.Melnik, PhD.