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The authors present in this paper an explanation of gaseous detonation based upon what are considered incontrovertible laws, and show by the functioning of these well understood natural laws that gaseous detonation is a phenomenon that does not require any hypothetical assumptions to account for its existence. The physical conditions that must exist within an enclosed container when it is filled with an explosive mixture of gases and these gases are ignited are stated and analyzed mathematically, and an application of this analysis is made to the internal-combustion engine. The apparatus and the procedure are described inclusive of photographs and charts, and it is shown how the formulas can be applied (a) for constant throttle, by varying the temperature of the entering charge and (b) for constant temperature, by varying the throttle opening and the compression-ratio. The results are illustrated and discussed in some detail.

The rail motor-cars now used by the New York, New Haven & Hartford Railroad are illustrated and commented upon, and statistical data regarding their operation are presented. The features mentioned include engine type and size, transmission system, gear-ratio, double end-control, engine cooling, heating by utilizing exhaust gases and exclusion of exhaust-gas fumes from the car interior. A table gives revenue data.

The various methods employed to measure detonation or fuel knock in an internal-combustion engine, such as the listening indicator, temperature and bouncing-pin, are discussed and the reasons all but the last cannot be employed to give satisfactory indications of the detonation tendencies of fuels are given. The bouncing-pin method, which is a combination of the indicator developed by the author and the apparatus designed by Dr. H. C. Dickinson at the Bureau of Standards, is illustrated and described. In this method the evolution of gas from an electrolytic cell containing sulphuric acid and distilled water measures the bouncing-pin fluctuations in a given period of time. The accuracy of this method of comparison is brought out in a table. The qualities that a standard fuel must possess are explained and the objections to a special gasoline are pointed out.

Stating that present internal-combustion engine fuel is too low in volatility for economical use and that this is the cause of engine-maintenance troubles, the authors believe that, since it is not possible to obtain the more volatile grades in sufficient quantity, the only hope of remedying this condition is to learn how to use the heavy fuel, and that the most promising method of doing this lies in the effective use of heat. As the experimental data regarding the best temperature at which to maintain the metal in a hot-spot manifold and the range of temperatures available in the exhaust gases are meager, the authors experimented in the Purdue University laboratory to secure additional data. They present a summary of the results.

After stating that the meaning of the term “gasoline” seems to be generally misunderstood for the reason that it has been assumed that gasoline is, or ought to be, the name of a specific product, the author states that it is not and never has been a specific product and that although gasoline has a definite and generic meaning in the oil trade it has no specific meaning whatever. It means merely a light distillate from crude petroleum. Its degree of lightness, from what petroleum it is distilled and how it is distilled or refined are unspecified. Specifically, “gasoline” is the particular grade of gasoline which at a given moment is distributed in bulk at retail. It can be defined with reasonable precision as being the cheapest petroleum product acceptable for universal use as a fuel in the prevailing type of internal-combustion engine.

The data given in this paper were obtained from an investigation by the Bureau of Mines in cooperation with the New York and New Jersey State Bridge and Tunnel Commissioners to determine the average amount and composition of the exhaust gases from motor vehicles under operating conditions similar to those that will prevail in the Hudson River Vehicular Tunnel. A comprehensive set of road tests upon 101 motor vehicles including representative types of passenger cars and trucks was conducted, covering both winter and summer operating conditions. The cars tested were taken at random from those offered by private individuals, corporations and automobile dealers, and the tests were made without any change in carbureter or other adjustments. The results can therefore be taken as representative of motor vehicles as they are actually being operated on the streets at the various speeds and on grades that will prevail in the tunnel.

The purpose of piston rings in an internal-combustion engine is to reduce to a minimum the leakage of gas from and the seepage of oil into the combustion-chamber. Asserting that the widely held idea that the leakage of gas past the piston can be eliminated by the use of good piston-rings is incorrect, the author states three possible paths for such gas-leakage and, after commenting upon them, discusses diagonal and lap joints and the subject of leakage with special reference to them. After considering the design of rings for gas-tightness, the author shows a fortunate mathematical relationship, in connection with the application of uniform radial pressures, regarding the bending-moment stresses. Oil leakage is treated in a similar manner and the conclusion is reached that the properties of the material used are of extreme importance.

Stating that the knowledge now available does not permit an exact scientific definition of flame and giving the reasons, in this paper the author regards flames as gases rendered temporarily visible by reason of chemical action, discusses their physical rather than their chemical aspects and, unless otherwise indicated, refers to the flames of common gasoline and kerosene only. To gain a reasonably clear understanding of the requirements and characteristics of the different kinds of flame, it is necessary to begin with a study of atoms and molecules. The author therefore discusses the present atomic theory, the shape of the atom and molecular structure, and follows this with a lengthy detailed description of the beginning of combustion. The requirements and characteristics of the inoffensive variety of combustion are considered next and nine specific remedies are given for use in accomplishing the burning of heavy fuels with a blue flame in present engines.

Flame propagation has received much attention, but few results directly applicable to operating conditions have been obtained. The paper describes a method devised for measuring the rate of flame propagation in gaseous mixtures and some experiments made to coordinate the phenomena with the important factors entering into engine operation; it depends upon the fact that bodies at a high temperature ionize the space about them, the bodies being either inert substances or burning gases. Experiments were made which showed that across a spark-gap in an atmosphere of compressed gas, as in an engine cylinder, a potential difference can be maintained which is just below the breakdown potential in the compressed gas before ignition but which is sufficient to arc the gap after ignition has taken place and the flame has supplied ionization. These experiments and the recording of the results photographically are described.

ON the basis that it is impossible to state the case for either the airship or the heavier-than-air machine without some comparison of the two, the author discusses relatively features, points of merit or superiority and the fields of usefulness thus far disclosed in the rapid development of the craft. Progress since 1914 is outlined, a brief history to date is included and the way prepared for consideration of the possibilities of long-distance flight. A comparison of the features given emphasizes strongly the point that the airplane is mainly a high-speed, short-distance carrier, while the large rigid airship is essentially a medium-speed long-distance carrier. Each type has a distinct sphere of activity; the airship in transcontinental, transoceanic traffic; the airplane in feeding the terminals of the airship with passengers and, possibly, certain kinds of freight.

BUREAU of Mines refinery statistics for the calendar year 1918 show a production of different types of petroleum fuel products represented by the following approximate figures: Added to this are 3,100,000,000 gal. of crude oil, used as fuel without refining. The statistics do not distinguish the different classes of fuel oils, and the following provisional estimate has been made: Processing or refining costs for the different oils are difficult to estimate and of little significance in determining the selling price, which is controlled by the law of supply and demand. All types in the last list can be used in so-called heavy-oil engines, but the gas oil and light residuum are most desirable in the order given. They are less plentiful than the heavy-residuum type which generally cannot be used without special equipment for preheating. The proportionate yield of gas oil can be increased if a sufficient demand is developed.

Manufacturers of carbureters and ignition devices are called upon to assist in overcoming troubles caused by the inclusion of too many heavy fractions in automobile fuels. So far as completely satisfactory running is concerned, the difficulty of the problem with straight petroleum distillates is caused by the heaviest fraction present in appreciable quantity. The problems are involved in the starting, carburetion, distribution and combustion. An engine is really started only when all its parts have the same temperatures as exist in normal running, and when it accelerates in a normal manner. Two available methods, (a) installing a two-fuel carbureter, using a very volatile fuel to start and warm-up the engine, and (b) heating the engine before cranking by a burner designed to use the heavier fuel, are described and discussed.

ENGINEERS have different ideas regarding highly efficient and moderately efficient engines, but designers dare not ignore the fact that the public requires today a small very high-speed engine, with good torque at low speeds, and capable of revolving efficiently at very high speeds. These two characteristics are difficult to attain, since in practice one is really opposed to the other. To obtain high speeds with power, the valve areas, valve parts, carbureter, etc., should not be restricted in any way, while to get a good mixture at low speed with heavy torque means a different valve-setting and more or less restricted port and valve areas, etc., to secure high gas velocities. The author states that the fundamentals of high-speed engines are high volumetric efficiency; high compression, to aid in obtaining rapid combustion at high speeds, and light reciprocating and rotating parts, to secure high mechanical efficiency.

THE impression that recent aircraft experience should have taught engineers how to revolutionize automobile construction and performance, is not warranted by the facts involved. Aircraft and automobiles both embody powerplants, transmission mechanisms, running gear, bodies and controls, but their functions are entirely different. The controls of an airplane, except in work on the ground, act upon a gas, whereas with an automobile the resistant medium is a relatively solid surface. Similarly, the prime function of the fuselage is strength, weight considerations resulting in paying scant attention to comfort and convenience, which are the first requirements of an automobile body. Aircraft running-gear is designed for landing on special fields, and is not in use the major portion of the time. The running-gear is the backbone of an automobile, in use continuously for support, propulsion and steering; hence its utterly different design.

The author states as his object a review of what has been done and what must be done to make tractors successful in operating on low-grade fuels, especially kerosene. He takes up in order the four principal methods in common use of applying heat to vaporize kerosene, pointing out the advantages and disadvantages of each method and of its modifications. The author then cites various experiments with different types of carbureters in burning kerosene, drawing at length upon his own experience in this connection. He cites difficulties with gas distribution, manifold condensation, pistons and spark-plugs and points out that carbureter design is inseparable from considerations of tractor engine and manifold design. That better progress has not been made in the past in developing kerosene-burning tractor engines is stated to be largely owing to the fact that there has not been sufficient cooperation between engine and carbureter manufacturers.

The author first compares mineral oils with certain other liquids in order to point out clearly certain of their characteristics. He then shows the economic benefits that would result from making more of the crude available for use as fuels. He discusses such topics as cracking methods in use, advantages of dry gas, initial flame propagation, gas producers, hot mixtures, wet mixtures and difficulties of correcting existing engines. He concludes by proposing as a solution of the gasoline problem the more general use of superheated homogeneous fixed dry gases made in vaporizing devices independent of engine cylinders, and outlines means for attaining this end. Performance data covering the use of mixtures of kerosene and gasoline on several cars are included in a table, and several charts throughout the paper illustrate many of the topics discussed.

The author states that the objects of the paper are to define and trace the development of the various processes of carburetion, and to offer such suggestions along these lines as may assist the investigator in developing motorboats, automobiles and self-contained unit motor cars for railway purposes. The surface carburetor is mentioned chiefly as of historic interest. In considering the jet carbureter the author discusses the proportion of gas desired, the effect of the varying inertia of the air and the liquid gasoline and the breaking up of the combustible needed. Following sections review the devices for using kerosene, such as gasoline jet carbureters to which heat is applied, devices of the fixed gas type, the introduction of combustible directly into the cylinder, forcing combustible directly upon a hot surface in the cylinder and devices which raise the combustible to the boiling point.

A procedure has been developed for evaluating equivalent drive cycle emission results from raw exhaust gas emissions data obtained from an engine under test on a computer controlled Vehicle Simulator Engine Dynamometer. The emitted species data is integrated with the air intake flow rate to determine the total mass of emissions, after correcting for the reduction in exhaust gas mass due to precipitation of the moisture of combustion. This procedure eliminates the need for the Constant Volume Sample (CVS) System attached to the vehicle exhaust while undergoing simulated drive testing on a chassis dynamometer to evaluate compliance of the test vehicle with the Australian Design Rules, ADR27 and ADR37. Sources of error with the procedure are examined by comparing the fuel consumption measured using a volumetric technique during the test with that evaluated by a carbon balance procedure as given in the Australian Design Rules.

An all-ceramic swirl chamber has been developed and analyses and evaluations concerning the strength of silicon nitride ceramic (Si3N4) have been performed with a view to using it for the entire internal wall surface of the swirl chamber. The strength characteristics of Si3N4 and their effect and variation have been determined. On the basis of measurements and analyses of thermal stresses, assembling stresses, etc., investigation of the most suitable construction and assembling methods to reduce load stresses on ceramic, and various kinds of duration tests, the swirl chamber has been confirmed to have the required durability. This engine was found to comply with the 1987 U.S. diesel particulate regulation.