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The liquid injection technique (LIT) is a simple method for observing diesel spray behavior. Excellent visibility of the spray is attained by injecting the fuel into a clear hydrocarbon liquid instead of a pressurized gas. Earlier research with the technique is reviewed, and questions are posed regarding the mechanism of spray visibility in the liquid and the comparability of penetration measurements in liquid and gas. Experimental results lead to the conclusion that visibility in the liquid is due to cavitation and penetrations in a liquid and a dense gas are generally equivalent. Applications of the liquid injection technique to diesel injection problems are briefly discussed from both a research and hardware oriented viewpoint.

This paper describes full-scale engine studies conducted to determine the feasibility and compatability of ammonia combustion in various systems. Briefly outlined is the spark-ignition investigation undertaken by the Army Laboratory to learn the potential and effect of ammonia as a fuel and to study the influence of engine variables on combustion. A study of compression-ignition performance was made to ascertain the ability of ammonia to be pumped in existing injection systems and various means of achieving ammonia combustion were explored. Conclusions drawn from these studies on the use of ammonia as a fuel are given.

An engineering study was conducted to gain a better understanding of the system and fuel factors affecting low temperature pumping performance of CITE fuels. The system investigation illustrates that filter pore size, area, flow rate, and fuel charge were important variables and that properly designed and placed components can significantly influence the temperature to which fuels can be pumped. The study showed that very small amounts (2-5%) of frozen hydrocarbons can cause filter plugging and that the presence of insoluble fuel products at low temperatures also contribute to the problem. The program also pointed out that the aromatic portion of the fuel can be as much at fault as the saturates. The paper emphasizes the need for further research to better understand the relationship of the hydrocarbon group and subgroup composition in establishing low temperature fuel behavior.

When combustion products, commonly called “blowby,” are prevented from reaching an engine's crankcase, sludge formation is inhibited and lubricant life extended. This paper discloses the concept, developed at the Army Fuels and Lubricants Research Laboratory, which prevents leakage of blowby gases into the crankcases of piston engines. “Blowby diversion” is accomplished, by one or a combination of four basic methods, at the piston ring zone where the blowby gases are intercepted after leaking by the bottom compression ring, but before reaching the crankcase. Single-cylinder engine studies have demonstrated that the principle of blowby diversion is feasible and can prevent better than 90% of the blowby from entering the crankcase. The studies further indicated a significant reduction in sludge formation rates (increase in engine cleanliness), with decreases in ring wear and air pollution. Blowby diversion appears to be reliable and easily adapted to conventional engines at low cost.

The influence of low temperature on fuel injection and combustion in compression-ignition engines was studied. Both unit injector and plunger pump-remote injection nozzle systems were investigated, and findings on spray characteristics such as penetration, cone angle, and injection timing are presented. Fuels used in these tests ranged from the minimum practical viscosity as well as varying densities through the use of Blended Fuels. A summary of findings and test results are included, together with recommendations for subsequent investigations.