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Closed crankcase ventilation prevent harmful gases from entering atmosphere thereby reducing hydrocarbon emissions. Ventilation system usually carries blowby gases along with oil mist generated from Engine to Air intake system. Major sources of blowby occurs from leak in combustion chamber through piston rings, leakage from turbocharger shafts & leakage from valve guides. Oil mist carried by these blowby gases gets separated using separation media before passing to Air Intake. Fleece separation media has high separation efficiency with lower pressure loss for oil aerosol particles having size above 10 microns. However, efficiency of fleece media drops drastically if size of aerosol particles are below 10 microns. Aerosol mist of lower particle size (>10 microns) generally forms due to flash boiling on piston under crown area and from shafts of turbo charger due to high speeds combined with elevated temperatures. High power density diesel engine is taken for our study.

Just down the road from SAE International’s headquarters in Warrendale, Pennsylvania, Mark Sokalski has been quietly working out how to maximize piston-driven engine efficiency – with an internal combustion engine mechanism that doesn’t follow the norm.

This procedure covers ultrasonic inspection of tubular, centrifugally-cast, corrosion-resistant steel cylinders.

This paper reports on the research and development challenges experienced from dynamometer testing of a spark ignition UAV engine operating on heavy fuel. The engine is a segregated scavenging two stroke engine with air charge delivery by means of integral stepped pistons overcoming durability issues of conventional crankcase scavenged engines. A key element of the experimental study builds upon performance development to address the need for repeatable cold start on low volatility fuel thereby eliminating gasoline from UAV theatres of deployment. Lubrication challenges normally associated with crankcase scavenged two stroke engines are avoided by the integrated re-circulatory lubrication system. The fuel explored in this study is kerosene JET A-1.

Interest in 2-stroke engines has been recently renewed by several prototypes, developed for the automotive and/or the aircraft field. Loop scavenging, with piston controlled ports is particularly attractive, but the configurations successfully developed in the past for motorbike racing (in particular, the 125cc unit displacement, crankcase pump engines), are not suitable for automotive applications. Therefore, new criteria are necessary to address the scavenging system design of the new generation of 2-stroke automobile/aircraft engines. The paper reviews the transfer ports optimization of a loop scavenged 2-stroke cylinder, whose main parameters were defined in a previous study. The optimization has been carried by means of a parametric grid, considering 3 parameters (2 tilt angles, and the focus distance), and 3 different engine speeds (2000-3000-4000 rpm, assuming a Diesel engine). A set of scavenging CFD-3d simulations have been performed by using a customized version of KIVA-3V.

This SAE Aerospace Recommended Practice (ARP) defines a method of numbering aircraft engine cylinders.

Concern about the consequences of fuel dilution on engine oil properties are intensifying due to the increasing use of E25 and E85 fuel in passenger cars. Notably, such concerns are about the effect of emulsion formation and stability in crankcase oils by E25 or E85 fuel and water dilution on vehicle operation at cold-start conditions. Different types of Viscosity Index Improver (VII) chemistries were evaluated for their effects on emulsion formation and engine oil characteristics. Emulsions were prepared with fresh and used passenger car motor oils using the ASTM D7563 method for emulsion retention. The emulsion properties were evaluated after storage for 24 hours at two different temperatures. Separate oil/gasoline and emulsion (ethanol/water/oil) phases were observed for fresh oil emulsions. None of the emulsions exhibited a separate water phase, regardless of the type of VII in the oil.

This SAE Aerospace Recommended Practice (ARP) defines a method of numbering aircraft engine cylinders.

The crankcase-scavenged two-stroke-cycle engine is preferred in cases where low weight and high power output are paramount requirements. These qualities are most important in small pilotless aircraft. It was found that the main problem in the use of two-stroke cycle engines for this purpose, is a sharp decrease in the engine power with the increase in altitude. This is attributed not only to the low density of the ambient air, but also to the deterioration of the efficiency of the gas exchange process. In order to improve the engine performance at high altitude, it is proposed here to employ a stepped-piston engine. The engine is constructed of a stepped piston and a single stepped cylinder thus forming three compartments; a power, a compression and a crankcase compartment. In this arrangement, the fresh charge is compressed in the compression compartment before it enters the crankcase compartment.

This paper traces the historical development of the BICERI variable compression ratio piston and its use in a number of engines. In early petrol experiments a variable compression piston covering the range from 6.5:1 to 16.5:1 showed significant efficiency improvements on 70 octane petrol. In the diesel engine field, Teledyne Continental increased the power of a V12 direct injection tank engine from 550 hp (30 hp per litre) to 1475hp (80 hp per litre) retaining the original crankcase and structure. At BICERI the output of a supercharged research engine was increased to 40 bar bmep with a peak cylinder pressure of only 165 bar. Military application lapsed with the preference for gas turbine engines, but the time is now right to explore the capabilities of variable compression within the wider automotive scene. Volkswagen have been working on a variable compression engine and have shown fuel consumption improvements up to 13% together with lower emissions.

For the past two decades, since the introduction of the ashless dispersant aviation oils, the quality of these oils has remained relatively constant. These “single grade” aviation oils, however, required changing as the weather changed whether the usual 50 hours of service has been accumulated or not. In fact, there have been frequent reports of aircraft engines being ruined because heavy SAE 50 (Commercial Grade 100) oils were in the crankcase when they were started and operated in cold weather without engine pre-heat. Present modern aircraft can easily fly from a cold area, with a light SAE 30 (Commercial Grade 65) oil in the crankcase, to a hot area and experience high wear due to boundary lubrication conditions and high oil consumption.

This paper characterizes the features and describes some of the benefits of the present generation of multigrade “MS” oils. Particular emphasis is placed upon viscosity retention characteristics as a function of the stability of the viscosity index improver. Comparative automobile field tests in private commuter, taxicab, and highway service are shown for both SAE 10W-30 and a carefully compounded SAE 10W-40 oil. Observations of cylinder and piston ring wear, crankcase deposits, PCV valve cleanliness, and oil economy are reported.

SOME years ago the SAE Ignition Research Committee expressed its need for a standardized single-cylinder engine which would take actual full-scale aviation engine cylinders into the laboratory under accurately controlled operating conditions for aviation spark-plug research. Such an engine was built by the author's company and displayed at the SAE Semi-Annual Meeting in 1937. Although this engine did meet the needs of the spark-plug manufacturers, it did not fill the needs of the petroleum industry, which was interested primarily in lubricating oil and fuel tests. A volunteer group, organized at the 1937 SAE Semi-Annual Meeting, first listed the features which such a design must include, and then a small design subcommittee was formed to study and coordinate the requirements. Five complete designs were made before a combination was developed which appeared to meet all requirements in a satisfactory manner.

THE aircraft engine producer faces three unique conditions which make quantity production a complex problem: first, intensely rapid development; second, great pressure for perfection in reliability; and third, an unusually large number of variables in the product. The author points out that these special conditions all tend to emphasize the importance of quality in the design engineering, with particular reference to simplicity. The oil-circulating system of the aircraft engine is described as an example of one source of production and service troubles. Design improvements which have overcome these troubles are explained, including a new steel crankcase, the end-sealed master rod bearing, the “uniflow” piston, and a self-cleaning oil filter.

AFTER outlining the history of development of the Packard X engine, the author states the legitimate position in aviation deserved by the water-cooled aviation-engine of this type and predicts large increases in the size, speed and carrying capacity of airplanes within the near future. Passing then to a discussion of the important features of the X-type engine, various illustrations of its parts are commented upon. The cylinders are built-up from steel forgings, with all welds arranged so as to be subjected to no excessive alternating stresses. The novel features of this cylinder design lie in the fact that the valve seats are entirely surrounded by water and that water space is provided above the combustion-chamber and below the top plate of the cylinder. The cylinder-head is extremely rigid, resisting deflection and assuring the maximum integrity of valve seats. The valve ports are machined integrally with the cylinder-head and are not welded thereto as in the Liberty engine.

Advances in airplane performance during the last few years may be ascribed mainly to advances in aerodynamics and to improvements in powerplants. The latter have resulted in producing more power for the same weight of engine and smaller over-all dimensions for engines of the same power-rating. The accompanying paper describes two engines of 500 and 800 hp. respectively that have been recently developed by the Packard Motor Car Co. for aircraft service. When these engines are compared with previous types they are found to be more compact and to produce more power per pound of weight. When each is operated at its rated speed, the Model 1500 engine develops 100 hp. more than the Liberty while weighing 140 lb. less, and the Model 2500 engine develops 250 hp. more than its predecessor, the Model 2025, with a decrease in weight of 75 lb.