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Preliminary results of design studies involving the use of small gas turbine engines to reduce noise and exhaust emissions from aircraft are reviewed. Comparisons of reciprocating engines with small turboprop engines indicate lower carbon monoxide and hydrocarbon emissions for the latter engine type at all power settings. The piston engines show somewhat lower nitrogen oxide production above 20 percent power, consistent with the fuel-rich operation of such engines. Small gas turbine engines have higher CO and unburned hydrocarbon emissions at low power and lower NO/sub x/ levels at higher power than large gas turbines. The comparatively poor performance of the small engines at low power is due primarily to operation at low combustor pressure and temperature as well as to a high ratio of combustor surface area to volume and to the use of relatively simple and low-cost combustor and fuel systems. The good NO/sub x/ performance at high power is due principally to lower levels of combustor inlet pressure and temperature. Early development data indicate that major reductions in CO and unburned hydrocarbons can be achieved with only small increases in NO/sub x/ by means that do not imply appreciable changes in the size, weight, or complexity of themore » gas turbine engines.« less

A study was conducted on the feasibility of totally cooling a single-cylinder diesel engine by direct injection of water into the combustion chamber. The term “total cooling” can be taken to mean stabilized cooling at all loads and speeds so as to eliminate need for conventional cooling jackets, cooling fins, or oil spray jets. The engine used was a CLR Direct Injection Diesel with 42.5 cubic inch displacement and a compression ratio of 16:1. Most of the running was at 1800 rpm and 92 psi IMEP. Separate measurements were made of heat rejection to the cylinder head, liner, and crank-case oil to determine more accurately where the cooling effect was being applied. Water injection was by means of a Bosch pump and various pencil-type nozzles installed, adjacent to the fuel injector in the cylinder head. Port injection and port induction were also briefly investigated. A five-hole, 90° included angle nozzle was used, as was a three-hole, 30° included angle unit. For comparison, a nozzle directing one spray obliquely at the cylinder wall was also tested. Firing pressure was monitored using a piezo-electric transducer; both pressure-time and pressure-volume (indicator) records were obtained. In order to determine timing of both fuel and water injection, needle lift was monitored using a differential transformer pickup. The results of this study indicate: t Optimum total engine cooling by direct water injection was accomplished over a wide range of water injection timings (from 450 to 720 CA degrees after TDC power stroke) at water/fuel ratios of 2.9 to 3.7 with output power and brake specific fuel consumption improved 5 to 20%, respectively, over that with the standard jacket-cooled CLR engine. Emissions are affected in an expected manner by the presence of water: NO x is decreased, sometimes substantially, while the other emissions (HC, CO) tend to increase. When cooling the exhaust, the condensate becomes an effective scrubber of sulfur oxides. NO x was not significantly reduced by scrubbing, but if the condensate is made sufficiently alkaline (pH>8), CO 2 was unintentionally scrubbed out. The quality of the uncondensed exhaust for turbocharging is attractive. A theoretical gain of about 17.5% in available exhaust energy due to generation of steam was calculated, along with a temperature decrease of several hundred degrees Fahrenheit. Water contamination of the lubricating oil varies from negligible to extreme, depending on injection quantity, timing, and spray pattern. By not directing water at the liner wall, and by keeping the oil above 212°F, one can maintain the oil in a dry condition. Based on this work, several pertinent recommendations have been made: (1) utilize water injection for short-duration, very high-output operation which would otherwise be destructive due to thermal overload; (2) use water induction cooling in event of loss of conventional liquid coolant; (3) utilize exhaust scrubbing in stationary applications to permit burning of high-sulfur fuels without producing sulfur oxide emissions; nitrogen oxides could likewise be reduced by the injection of small amounts of water; and (4) since 2-stroke-cycle engines are an important category of diesel engines, some work similar to this effort should be done to this engine type; prospects are good for success, but conditions are apt to be more restrictive.

This paper presents the results of a study of the air motion in a motored four-stroke direct injection diesel engine using hot-wire anemometry. The effects of engine speed, valve masking and supercharging on mean air swirl have been studied. A theoretical analysis is developed for the mean air swirl which in general shows good agreement with the experiments reported here and with the measurements of other workers on similarly sized engines. The problem of ‘squish’ has been investigated and it is shown to be the radial component of the spiralling swirl flow entering the combustion chamber. Reasonable agreement has been found between measurement of the radial flow component at the edge of the combustion bowl and a theoretical analysis that considers the bulk radial flow of air to the combustion bowl during the last 30°-40° b.t.d.c. of the compression period.

The dynamics and properties of a small jet of plasma produced by allowing a pulsed discharge to expand from a cylindrical cavity have been investigated. A model has been developed, which is based on the premise that the spark heats the gas within the cylinder and produces a supersonic, strongly asymmetric pressure wave propagating, essentially in one direction only, into the cold surrounding gas. Quantitative measurements of the properties of this plasma jet agree reasonably well with the model. Experimental measurements on a propane-air flame and a gasoline internal combustion engine indicate that this device may, in a practical sense, be useful for igniting fuel lean combustion.

In the first part of this study, a one-dimensional quasi-steady-state heat transfer model is developed for an axial forced flow system in rotary combustion engines. This computer model is useful in optimizing the cooling system in accordance with the heat input from the combustion chambers. In the second part of this study, a two-dimensional quasi-steady-state heat transfer model is developed for an axial forced flow cooling system in a rotor housing in an effort to minimize the thermal stresses and the thermal distortions of the trochoidal surfaces. In the third part of this study, a two-dimensional transient heat transfer model is developed for an axial forced flow cooling system in a critical portion of the rotor housing in order to determine the critical thermal loads that occur in the through-bolts during the sudden acceleration of a cold rotating combustion engine.

The periodic pressure fluctuations found in internal combustion engine intake pipes are analysed by determining initially the steady oscillatory part of the response. Then, by considering the analytical solution of a simpler model, the transient response is formulated enabling the complete pressure at a point in the intake pipe to be found. The air flow in the intake pipe is considered to have viscous losses but these effects are ignored in the cylinder, as are any thermodynamic influences. Experimentally derived results are presented for comparison with the analysis.

The paper describes the design, hardware, testing, and performance of a breadboard semi-closed cycle power system proposed for undersea operations by the Naval Undersea Center. The work was performed to prove the feasibility of the system. The system includes a commercially available spark-ignition engine, which operates on natural gas, oxygen, and recirculated exhaust gas, and a specially designed liquid oxygen/excess exhaust gas converter. The converter utilizes heat from dry, precooled exhaust gas to vaporize liquid oxygen and provide oxygen for the engine. While providing heat for liquid oxygen vaporization, the exhaust gas becomes frozen. The well-insulated converter is designed with ample storage capacity for both liquid oxygen and solidified exhaust. Nonoptimized hardware provided reliable airbreathing and nonairbreathing operation. Tests indicate that the approach is feasible for undersea applications.

The current Navy philosophy for marine gas turbine engine development is to marinize an existing aircraft turbo jet engine. The FT9 Marine Gas Turbine Engine is a 33,000 horsepower version of the Pratt and Whitney JT9D engine, which powers the 747 aircraft. Marinization of the JT9D basically involves removal of the fan section, addition of a power turbine, structural modification to several components, and material changes to provide corrosion-resistance in the marine environment. Characteristics and ratings of the individual engine components are discussed as well as the assembled engine. The FT9 design incorporates the modular replacement concept. Modular replacement permits replacement of short-life components such as the hot-section without removing the engine from its mounts. The FT9 specification requires development of a condition monitoring system as an integral part of the engine development. Thus, provisions for sensor installations are incorporated in the design. Accelerometers are installed on the internal engine bearing housings to provide improved vibration signals. These accelerometers are mounted on rods such that they are removable without engine disassembly. Extensive borescope provisions are included to provide capability to inspect all hot-section components without disassembling the engine. The engine life-limiting component is the hot-section because of the susceptibility of the blade and vane materials to sulphidation/oxidation at the temperatures encountered with the advanced engines. Sophisticated Made and vane cooling is used to allow high turbine inlet temperatures while keeping blade metal temperatures in a region where sulphidation/oxidation is only moderately active. Coatings are added to blades and vanes to extend engine life. Three FT9 engines will be delivered to the Navy. The target date for provisional Service Approval of FT9 is mid-1978. FT9 will provide the U.S. Navy with the most advanced marine gas turbine with the highest power to weight ratio engine available for naval surface propulsion.

Fuel dilution of lubricating oils in small diesel engines is normally attributed to fuel leaking past seals, pumping elements or feed pump diaphragms. Some authorities advise that dilution greater than 10 to 15 per cent is inadvisable; others advocate an oil change if the viscosity is more than an S.A.E. grade. Another possible cause of dilution depends on fuel properties, nozzle design and aspects of air-How into a cylinder. The fuel introduced in this way plays some part in the combustion process and influences engine smoke levels. The dilution so caused is speed and temperature dependant. The paper describes tests to establish the basic characteristics, the mechanism at work and modifications to minimize this cause of oil dilution. Some tests are included to show that some fractions of fuel that is diluting lubricating oil can evaporate during engine operation; heavier fractions, however, are more likely to persist.

A combustion model is presented to account for the nitric oxide formation in diesel engines at all operating conditions. The paper tries to introduce the concept of variable air-fuel ratio estimated to exist during diesel combustion. Analytical solutions are found to be in good agreement with experimental results. Further investigations will be directed to diesel engines having combustion systems other than the M.A.N.-FM system, and to possible remedies to reduce the formation of nitrogen oxides.

A new semi-analytic method of predicting journal loci in diesel engine bearings has been developed. The original feature is the use of an approximate solution of the dynamic Reynolds equation which is similar to, but very much more accurate than, the analytic short bearing solution. In an example it is shown that the results predicted by a computer program based on the new analysis lie within the scatter of results given by supposedly “exact” methods.

Over the past quarter of a century, British-designed marine propulsion diesel engines have more than doubled their power output per cylinder. During the same period weight per kilowatt, and engine length per kilowatt, have both been reduced by nearly 75 per cent, specific fuel consumption has been reduced, and reliability has improved. This progress has been achieved by detail design improvements to even out stresses in components and to reduce temperature differences between hot and cold surfaces, combined with the application of the results of advanced computer methods to air flow, fuel distribution, and separation of rubbing surfaces by oil films. At the present stage of development the marine diesel engine is in many ways more advanced than the small automotive engine and can also compete in economic power production with prime movers at the opposite end of the scale such as super-large high-pressure steam turbines.

A digital simulation technique for determining the torsional response of internal combustion engines subject to constant and pulsating end item torques is described herein. A refined mathematical model of the engine and end item power shafts is utilized to determine their natural frequencies, mode shapes, torsional motions and stresses using a digital computer. The mathematical model is composed of a finite number of elements which simulate lengths of continuous, massive, elastic shaft with end attached lumped masses and springs. Forcing functions, obtained by Fourier series expansion of the engine pressure-crank angle curve, are applied at the lumped masses. The technique is applied to a small gasoline engine attached to a reciprocating compressor and to a large Diesel engine with a constant torque end item.

Theoretical and experimental work has been performed for the study of a new concept of a variable-thrust rocket engine using gaseous hydrogen/gaseous oxygen propellants. The engine concept has been developed for a throttling range of 10:1 with a constant low-pressure combustion chamber of 2 bars. Nominal maximum thrust of the test engine is 8000 N. The investigations have been directed on a comprehensive basis for the proposed rocket engine concept suitable for auxiliary propulsion in advanced space transportation systems. The hydrogen/oxygen propellant combination was used because of its high specific impulse, excellent cooling characteristics of hydrogen, pollution free combustion products, non-corrosive nature and relatively low cost. These advantages are of main interest for fully recoverable and reuseable vehicles. This report describes theoretical considerations on an optimum injector and combustion chamber concept. The program tasks were followed by a truncated experimental thruster program. It was directed toward the experimental evaluation of combustion chamber efficiency when varying thrust in a throttling range of 3:1, variation of mixture ratio and the amount of hydrogen mass for film cooling of the chamber wall. Recommendations for the nozzle design have been made for thrust modulation by varying the throat area.

The pattern of temperature distributions of gases in the combustion chamber of a rapid compression machine and in an internal combustion engine will be complex. And in this report, a successive approximation equation which gives the gas temperature measured by the infrared radiation pyrometer has been derived under the condition of nonuniform temperature distributions. The results agree with the measured temperature and the characteristics of the pyrometer have been investigated with hive model distributions which will occur in the combustion chambers. The pyrometer gives a little higher temperature than the average and the tendency will be more intensified as the ratio of the highest temperature to the lowest departs from unity and temperature levels become lower. The gas near the radiation detector affects the reading more than that located farther apart. Some examples to calculate the peak temperature of the gas in a combustion chamber have been presented.

The far field noise generated by cold air flowing through stationary and reciprocating exhaust poppet valves into a cylindrical duct or pipe has been investigated. A method of predicting the intensity and frequency spectrum of the noise generated in such circumstances in terms of the known or assumed geometry and flow characteristics of the valves is presented. Comparisons of the predicted frequency spectra with measured values show good agreement for steady gas flows through stationary valves and for unsteady flow through a simplified exhaust system of a motored single cylinder internal combustion engine.

The fundamental aspects of pollutant formation and control in spark-ignition engines are reviewed. The pollutants examined are oxides of nitrogen, unburned hydrocarbons and carbon monoxide. The engine concepts discussed are conventional carbureted spark-ignition engines, the Wankel, and different types of stratified charge engines. The basic pollutant formation mechanisms are related to the characteristics of the combustion processes which occur, in these different engines.

Cyclic combustion variations have been demonstrated to exist in a direct injection Diesel engine to a surprisingly large extent. With the aid of an on-line computer engine-test facility statistical and correlation analyses were carried out to verify a strong relationship between the cyclic combustion variations and variations in the timing of fuel injection. The importance of these cyclic variations in the reduction of nitric oxide emissions from the engine is shown by experimental results and computer combustion model predictions. The overall effect on nitric oxide emissions is, however, small over most of the operating range of the engine.

The surfaces of an internal‐combustion engine can be expected to radiate sound resulting from time‐varying gas and mechanical forces developed during the operating cycle. The rapid pressure rise accompanying spontaneous ignition of the fuel within the combustion chamber leads to the characteristic ’’knocking’’ noise of diesel engines. In contrast, the rate of change of pressure within the cylinders of spark‐ignition engines is comparatively slower, which results in less intense gas forces. Further, impacts between the piston and cylinder walls, or deformation of the crank mechanism, may be responsible for the noise of some engines. In both cases vibrational energy is radiated primarily by the crankcase and by nonstructural parts, such as the oil pan and valve covers. For air‐cooled engines there is significant radiation from the cylinder‐cooling fins. Engine‐radiated noise may dominate the overall noise spectrum of diesel‐powered trucks at speeds near 30 mph.Subject Classification: 10.60; 50.30, 50.50.

For various fuel-air mixtures and different compression ratios, the intake temperature was varied over the entire range of ***200°F (366K) down to − 100°F (200K) when employing a single cylinder spark ignited research engine fuelled with natural gas. Performance data such as knock and ignition limits the nature and extent of exhaust emission and chamber pressure cyclic variation were obtained. Means were then suggested for the interpretation of the above mentioned data in terms of engine operation on liquefied natural gas. The experimental work confirmed in general the attractive features of the use of natural gas as a fuel in a spark ignition engine operated under extremely cold intake temperature conditions and that emissions of pollutants were not significantly increased.

To facilitate the distinction among different engine types, this paper indicates first a general classification of gasoline engines. This classification contains the group of stratified charge engines, and shows that, within this group, the divided combustion chamber engine type constitutes a major subdivision. Three characteristic designs of this type of engine are described in some detail, and fuel economy and emission results are presented. Data obtained with one of these engines indicate excellent fuel consumptions, showing at light loads values close to those achieved by Diesel engines. Data also show that automobiles equipped with another of the engines described in the paper have passed, with ample margin, the 1975 Federal Emission Standards, without added devices for exhaust gas treatment, while maintaining satisfactory fuel economy. Some aims that should be pursued in order to achieve, simultaneously, both the optimal fuel economy and emission reduction potential of the stratified engine are outl...

The temperature dependence of the rates of the third-order reactions, Pb + NO + M and Pb + O 2 + M, have been investigated by monitoring atomic lead using time-resolved atomic absorption spectroscopy following pulsed irradiation. These reactions show negative temperature rate coefficients and are found to be too slow to contribute significantly to oxidation in the internal combustion engine and removal in exhaust gases.

The object of this study of stratified charge combustion was to investigate various combustion chamber configurations and to evaluate their potential for automotive engines with low exhaust emissions. In single cylinder engine tests with a prechamber of approximately 30% of the total swept volume, numer-ous parameters that influence the combustion process markedly, such as air fuel ratio, cross-section of the passage, injector and spark plug position, air throttling, etc., were studied. These tests were supported with high speed photographs taken from the mixing and combustion process in a combustion bomb. Investigations of various combustion chamber configurations have shown that, with regard to NO x -emissions, the divided combustion chamber comprising a main chamber and a prechamber is preferable. Greater control of mixture stratification can be achieved over a wide engine speed range. The reduction of the HC-emissions is a more difficult matter, although tests with the multicylinder engine confirmed that thermal oxidation in the exhaust system is very effective. A significant reduction of emissions with a minimum of power loss can only be obtained by accurate control of the fuel quantities supplied to the main and prechamber. While combustion stability at very lean operation is guaranteed, intake air throttling in the part load range is necessary to keep combustion temperature high enough for effective oxidation of CO and HC. For good mixture preparation, a modest swirl in the precombustion chamber is advantageous, although too high a swirl results in an unacceptable combustion pressure gradient. The spark plug must be located further down the flow line than the injector to facilitate ignition of the mixture in a broader engine speed range. The injection timing can be kept constant over the entire operating range of the engine.

This feasibility study of hydrogen as a fuel for future vehicle propulsion considers fuel availability, economics and the storage system. The compatibility of a hydrogen-air engine with possible future requirements is assessed. The rate of formation of nitric oxide, based on the rate kinetics in a hydrogen-air mixture, indicates a higher nitric-oxide concentration in the exhaust gas of a hydrogen engine than in the exhaust gas of an equivalent petrol engine. Methods of reducing the emission levels and the design changes are discussed.

A method of monitoring the quality of combustion in spark ignition gasoline engines using the spark plug's center electrode as a plasma probe is presented. Due to the ionized species remaining in the burned gases after combustion, a current is induced in a network attached to the spark plug's center electrode. The time dependence of this induced current is shown to correlate with the presence or absence and the time of occurance of the pressure component due to combustion in pressure transducer signals recorded simultaneously. Based on these correlations, three types of burns could be recognized from plasma probe signals: good burns, slow burns, and misfires. The specific correlation between the absence of a pressure component due to combustion and a corresponding absence of a plasma probe signal was used to form the basis for the operation of a one-channel engine misfire monitoring circuit.

Abrasive wear is the most decisive factor in determining the life of internal combustion engines. Methods based on radioactive tracers have been developed and are outlined for assessing the efficiency and selection of oil and air filters. Use of these methods would help to improve the life of internal combustion engines by better protection against abrasive wear.

This paper deals with the problems of constructing a sufficiently accurate mathematical model for a system consisting of an Internal Combustion Engine (I.C.E.) producing its normal cyclic variations of driving torque and a mechanical load with a governor providing discrete torque control.

Tests were ca r r i ed out on ro tor blades (Fig. 1) and guide vanes using fuel mixtures with various sulfur compound contents, to investigate the effect of sulfur compounds in fuel combustion products on the thermal fatigue strength of turbine blades and vanes, using the method previously descr ibed and a specially built gas dynamics test bench [1]. The investigation p rog ram provided for tests at fuel sulfur concentrat ions of 0.05, 0.4, 1.3, and 5 wt. %. The basic fuel used was lighting kerosene of grade KO-25 by GOST 4753-68 with 0.05 wt. % sulfur. The sulfur content was al tered by addition to the fuel of t e r t ia ry dodecyimercaptan (C12H25SH). The method chosen made it possible to evaluate the effect of sulfur compounds on gas turbine engine s t ructural elements in simulated operation on pract ica l ly all grades of fuel, because the sulfur content is of the f i rs t importance f rom the point of view of effect on metal proper t ies . The object of the present work is to investigate blade life, to study the kinetics of c rack origination and development, and to examine the nature of surface layer damage from the combined action of thermal

The study considers a range of possible effects on the transportation industry, satellite industries, the labor market, and the economy which may be anticipated in the event mass production of unconventional low emission automotive propulsion systems should occur, whether as a consequence of federal intervention, or not. A postulated 1 976 Otto Cycle Internal Combustion Engine equipped with a dual catalyst manifold reactor and other “conventional” emission control devices was compared in detail with a Regenerative Free Turbine Engine and a Rankine Cycle Engine, as specified by the contracting agency. Manufacturing costs, operating and ownership costs, consumer demand, inter-industry effects, employment, resource requirements, and international trade implications were analyzed in depth under a number of plausible sets of policy constraints and parametric variations. Principal conclusions are that conversion over a 10 year period is feasible, that manufacturing cost differentials are less critical than fuel...

Organo-metallic antiknock compounds in internal combustion engines - organic lead compounds for fuel additives

The small industrial gasoline engine of 1 to 10 h.p. presents difficulties in ensuring an adequate exhaust valve life, which are not present to the same extent with the automotive engine. Thus, these engines often operate under a continuous full-load duty which does not permit combustion chamber deposits to clear themselves as readily as does the fluctuating load of the vehicle engine. The fact that so many of the industrial engines are single-cylinder units means that one piece of deposit under an exhaust valve may bring the engine to a halt, whereas in the multi-cylinder vehicle engine, the unaffected cylinders would generally pull the engine round until the deposit had cleared itself. Consequently, when the operating conditions of the valve are made more severe by increasing the lead content of the fuel, the industrial engine is particularly vulnerable. The investigation described in this paper was carried out on five assorted water-cooled and air-cooled engines to establish the minimum modifications necessary to enable them to run for 1,000 hours between top overhauls using M.T. 80 fuel containing a maximum of 3.6 cu. cm. tetraethyl lead per Imperial gal. (T.E.L./I.G.). In addition to being the Services fuel, M.T. 80 can be regarded for this purpose as representative of the most highly leaded gasoline likely to be marketed commercially in the immediately foreseeable future. Under standard conditions, the water-cooled engines failed in 210–270 hours' full-load operation, and the air-cooled engines in 65–80 hours, owing to sticking of the valve stem in its guide. The tests and modifications are described in considerable detail. Although in general 1,000 hours' operation can be obtained on all these engines with comparatively simple modifications, premature failure was always liable to occur in a random manner, owing to deposits showering down into the cylinder. This situation would seem difficult to overcome by mechanical design alone. Some preliminary results of an approach from a chemical aspect, using additives in the fuel, and various additive and non-additive lubricants, are described.

A review is given of the development of self-propelled railway vehicles which utilize electrical transmission, paying particular attention to the ways and means of regulating the torque demand on the internal combustion engine which serves as the source of power, and the supply of power to the auxiliaries. Two general designs are discussed, and classified as ``differential field control'' and ``torque control.'' In differentiating between these two systems, two types of differential field control are outlined, giving their major advantages and limitations. The principle of torque control depending upon constant engine speed is discussed, enumerating its advantages over previous schemes. It permits the absorption of the entire engine output for any throttle opening and engine speed selected. The various relays and control devices necessary for proper operation of the scheme are described, together with the use of the auxiliary generator and main generator for compressor operation and battery charging. The appendixes deal with the design of auxiliary generators for differential field control and a short description of the method of limiting the torque required by means of a torque regulator and contactor. The problem of overcoming hunting of the system due to lagging of the field change and its solution are given. The differential field control comprises the minimum amount of apparatus consistent with operation of the car or locomotive and its auxiliaries.

SIMPLIFIED CONTROL OF THE MOTOR CAR has occupied the minds of designers ever since the earliest days of the industry. In the many attempts to make driving a car easier for the man‐in‐the‐street, steam was one of the forms of propulsion used until the early ‘thirties’ but when the internal combustion engine finally won the day, efforts were concentrated on finding something better than the friction clutch and manually operated gearbox for use in conjunction with this type of engine. Before World War II several fully automatic transmissions for passenger cars had already been developed, especially in the U.S.A., and it was during this war that these transmissions found application in fighting vehicles. With the return of peace, motor manufacturers turned to fully automatic transmissions in a big way. It is hardly surprising, considering the generally advanced state of mechanisation in that country, that in the volume production of this type of transmission the U.S. again took the lead. Also, the large output of the domestic motor industry offered the best chances for a favourable return on the considerable capital investments inherent to volume production of complex transmission designs.

This paper deals with the requirements for good combustion in the smaller high-speed direct-injection engines. Reference is made to the poor fuel distribution with current injection systems, and to the necessity of supplementary air movement. The level of air movement and the importance of squish motion are reviewed, and typical responses of the performance to swirl levels illustrated. From experimental evidence, including combustion photography, the mode of mixing is described, and its dependence upon the mass distribution of the fuel, and the influence of the chamber wall, discussed. The measurement of cylinder swirl under steady flow rig conditions is presented, and the correlation with chamber proportions and engine performance given. Recommendations are made on chamber requirements for wide speed operation and on inlet port configurations for optimizing flow and swirl conditions.

The paper brings out in a concise form the present status of heat engines and hydraulic turbines in commercial use today for the conversion of the energy found in fuel and water into mechanical power for the production of electric energy. The various types are compared as to relative importance, capacity, efficiency, weight, cost and economy, which are illustrated by curves plotted on kilowatt basis. (a) Reciprocating Steam Engine. (b) Steam Turbine (c) Gas Engine (d) Oil Engine (e) Hydraulic Turbine (f) Finance and Economics Curves are plotted showing the investment and fuel costs of the different heat engine units, on the basis of percentage of normal full load rating of machines.