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A technique for making a radiometric measurement of the deposit surface temperature in a methane-fired engine was developed. The wavelength region between 3.5 and 4.1 μm was investigated. It was determined that while the combustion gases were relatively transparent, the surface temperature measurements would contain some gas radiation. A method of averaging the measurements of many cycles and correcting these data for the gas radiation was developed. Time-averaged surface temperature was used in a steady-state heat transfer analysis to determine deposit thermal conductivity. Deposit thermal diffusivity was determined from a transient experiment in which the engine’s ignition system was turned off and the cooling response of the deposit and wall were measured.

A technique to determine time and space resolved particulate number density and size in the cylinder of an operating diesel engine is described and sample data presented. Basically the technique uses Mie scattering of a laser beam passed through the jet of gases leaking through a 0.015 diameter orifice inserted into the combustion chamber. Number density and size are inferred from measurements of scattering as a function of angle of scattering. The data show a linear relationship between exhaust measurements using this technique and Bosch smoke meter readings as well as an approximately linear relationship between in-cylinder measurements of number density and mass measurements made by collecting particulates flowing through the 0.015 in, orifice on a filter.

An intermittent sampling valve was used to investigate local fuel H/C ratio and species concentrations in an operating DI diesel engine. Additionally, predictions of carbon and hydrogen originating from particulates and nonmethane hydrocarbons (carbon and hydrogen remainders) were made by calculation. Sample H/C ratio was used to assess local fuel phase as gaseous or liquid. Evidence of intermediate species quenching in the lean region between spray plumes was found under low swirl. Reduction in the rate of penetration under high swirl may account for the observed loss in efficiency under this condition.

Gas concentrations, under different engine operating conditions, different locations relative to the fuel spray are presented. The gas that is sampled is “snatched” from a continuous flow sampling probe. The time of snatching is controlled. The concentrations of CO, CO2, NOx, and O2 are plotted against, crank position. The sampled gases were analyzed for concentration in the as taken state and after the sampled gas had passed through a heated catalytic oxidation converter. Analysis have been performed and plots are presented of the findings. The analytic procedure developed for the data analysis are presented in detail.

Preliminary computer studies indicated that the delayed mixing stratified charge engine concept might produce low emissions of nitrogen oxide and still provide reasonable efficiency and power. In the delayed mixing stratified charge engine concept a fuel-rich region is burned followed by air being mixed into the rich products. Nitrogen oxide formation was initially limited in the rich product mixtures because of the lack of oxygen and after mixing by the relatively low temperatures due to charge expansion. A single cylinder engine was used to simulate the delayed mixing stratified charge combustion process. A rich charge was drawn into the engine through the carburetor. Combustion was initiated with a spark; later air was injected to complete the combustion process. The results showed that emissions could be controlled by the delayed mixing combustion process. The engine specific power was also at reasonable levels. However, the engine efficiency was low.

IT IS WELL RECOGNIZED that the idling and part load fuel economy of diesel engines are better than throttled controlled spark ignition gasoline engines. Using well known principles the explanations for the difference are presented. Fuel consumption rate for similar engines and mileage for similar weight vehicles are presented in graphical form. Trends of demand, supply and reserve of crude oil for the World and the United States are shown in graphical form. Future supply scenario of crude oil is presented. The cost of making synthetic crude from coal is very roughly predicted.

This paper describes a new application of Karman vortex shedding frequency as a velocity sensor in a motored internal combustion engine cylinder. The probe design, experimental setup and data reduction procedures are described. The quality of data obtained depends strongly on the relative frequency distribution of the free-stream turbulence and of the vortex shedding induced by the vortex generator. The instrument was evaluated on a CFR engine equipped with a shrouded intake valve. The results are presented in terms of the airswirl ratio at several selected crank angle degrees versus engine speed. The limitations of the device were also demonstrated in L-head engine tests.

Various homogeneous charge and stratified charge engine configurations were studied at wide-open throttle conditions, using simplified computer models. An order-of-magnitude parametric study was performed to find those combinations of variables which predicted a low nitric oxide level. Extreme values of variables were studied for a homogeneous charge engine configuration, which could be difficult to do in a real engine. As expected, these calculations indicated that for practical engine operation the equivalence ratio of the mixture must either be very rich or very lean for a resultant low nitric oxide level. Two extremes of stratified charge engine operation were investigated analytically, in other words, immediate mixing of newly formed products of rich combustion with excess air (instantaneous mixing) and a period of rich combustion followed by air addition to the rich products (delayed mixing). Comparisons of power, efficiency, and specific NOx are presented.

Obtaining and maintaining a stratified charge in a practical engine is a difficult problem. Consequently, many approaches have been proposed and reported in the scientific and patent literature. In attempting to assess the most profitable approach for future development work, it is important to group together similar approaches so that one can study their performance as a group. Making such a classification has the additional advantage of helping to standardize terminology used by different investigators. With this thought in mind, a literature study was made and a proposed classification chart prepared for the different engine combustion systems reported in the literature. For the sake of completeness, the finally proposed classification chart includes homogeneous combustion engines as well as heterogeneous combustion engines. Because of their similarity of combustion, rotary engines such as the Wankel engine are considered as “reciprocating” although gas turbines are not included.

Instantaneous heat transfer rates at the interface of the working gas and the walls of a motored engine were studied. This paper details the influence on heat fluxes of engine speed, compression ratio, intake pressure, swirl ratio, location on the cylinder head surface, and the shape of the piston top. Equations are given to show the method of calculation used in deriving the data on heat transfer rates.

This paper describes a method and apparatus intended to minimize hydrocarbons (HC), carbon monoxide (CO), and nitric oxide (NO) in spark ignition engine exhaust by utilizing the unused displacement of the engine at part loads as an internal thermal reactor. The method used is to induct exhaust gas plus air into one portion of the cylinder and unthrottled fuel-air charge into the balance. The fuel-air charge is rich to minimize NO formation, but, as a result, the products of combustion contain HC and CO. Air is added to these products before re-induction to provide additional oxygen to complete the oxidation which is promoted by the high pressures and temperatures of compression and combustion. Load control is achieved by varying the relative amounts of fuel-air charge and recirculated exhaust. Experimentally, it was shown that the necessary stratification existed until the spark occurred but not thereafter.

An instrument was developed to measure absolute monochromatic infrared emission rates within an operating diesel engine. The instrument and data reduction system were developed for use in obtaining potential instantaneous rates of radiant heat transfer within an operating engine. Data are presented for variations of: engine speed, fuel-air ratio, fuel injection timing, intake air pressure, fuel injector nozzle spray patterns, fuel cetane numbers, fuel family, and fuel additives (tetraeythl lead and amyl nitrate). Also presented is an empirical correlation for instantaneous radiant heat transfer rates and some conclusions regarding radiant emission sources within the engine and their relationships to combustion processes.

Problem areas in engine simulation where the required information is lacking are discussed. The need for improved heat transfer, combustion, friction, and turbocharger models is discussed as are instrumentation needs for measurements of accurate pressure, radiant heat transfer, time-varying cylinder velocities, and instantaneous mass flow rates.

Ethylene, propylene, n-butane, and 1-butene, which make up a large portion of the photochemically reactive hydrocarbons in automobile exhaust, were reacted individually and as a mixture in a turbulent flow, heated reaction tube made of mild steel. Methods of predicting the total hydrocarbon disappearance by use of a general empirical equation are presented. Techniques for using hydrocarbon composition and carbon monoxide data to predict exhaust photochemical reactivity and CO concentration from total hydrocarbon disappearance correlations are suggested. Results show that total hydrocarbon reaction was generally strongly dependent on temperature and on oxygen concentration between 1% and 5%, and was less dependent on initial hydrocarbon concentration. Gas Chromatograph data showed that during certain individual hydrocarbon reactions, the formation of other photochemically reactive hydrocarbons could increase smog-forming potential despite a decreasing total hydrocarbon concentration.

Effects of engine parameters on performance can be investigated by using a mathematical model of the engine cycle, and the computed results may be used to optimize performance. The following design parameters were varied: crankcase clearance volume, exhaust and transfer port timings, exhaust and transfer port areas and bore/stroke ratio. Studies assumed both constant and variable exhaust pressures.

This paper describes a method for studying reactions of hydrocarbons in S.I. engine exhaust gases. The reaction of ethane is described using an Arrhenius model (experimentally E = 86,500 cal/mole) for the rate of ethane diappearance and empirical correlations for distributions of the products carbon monoxide, ethylene, formaldehyde, methane, acetylene, and propane as a function of the fraction of ethane reacted. The results show that the nature of partial oxidation products from a nonreactive hydrocarbon may be less desirable from an air pollution viewpoint than the initial hydrocarbon.

To determine the effects of knock in a spark-ignition, single-cylinder engine with cooled exhaust upon the exhaust composition, exhaust products (CO, CO2, and total hydrocarbons) were measured by non-dispersive infrared analyzers (NDIRA) and by a flame ionization detector (FID). Individual hydrocarbons were separated on a gas-liquid chromatograph. In fuel-rich mixtures, the FID indicated noticible decreases in the hydrocarbon concentrations in the presence of knock. The NDIRA did not indicate a decrease in the hydrocarbons at knock of lower intensities but showed decreases in hydrocarbons at knock of higher intensities. Chromatograms indicated a preferential decreases in acetylene at the time of knock, causing different responses at lower intensities. In fuel-lean mixtures, no apparent effect of knock on the hydrocarbons was indicated.

A detailed mathematical model of the thermodynamic events of a crankcase scavenged, two-stroke, SI engine is described. The engine is divided into three thermodynamic systems: the cylinder gases, the crankcase gases, and the inlet system gases. Energy balances, mass continuity equations, the ideal gas law, and thermodynamic property relationships are combined to give a set of coupled ordinary differential equations which describe the thermodynamic states encountered by the systems of the engine during one cycle of operation. A computer program is used to integrate the equations, starting with estimated initial thermodynamic conditions and estimated metal surface temperatures. The program iterates the cycle, adjusting the initial estimates, until the final conditions agree with the beginning conditions, that is, until a cycle results.

A complete electronic system for accurately and continuously measuring the indicated power of a reciprocating engine is presented in this paper. This includes an analog switching technique for separating the pumping power of a four-stroke cycle engine from the net cycle output. An analysis and evaluation of the individual components and circuits composing the complete instrument is made to determine the accuracy and limitations of the system and techniques used. The measurement of cylinder pressure, the weakest link in the entire system, is analyzed in detail to determine the pressure measuring requirements for the measurement of indicated power and the ability of some commercially available analog pressure transducers to meet these requirements. Data from a single cylinder, CFR, spark ignition engine are presented and used both as a means of evaluating the instrument and pressure transducers as well as to supply information on engine friction.

By the use of surface thermocouples to measure instantaneous temperatures, the instantaneous heat fluxes are calculated at several positions on the cylinder head and sleeve of a direct injection diesel engine for both motored and fired operation. Existing correlations are shown to be unable to predict these data. An analysis of convective heat transfer in the engine leads to a boundary layer model which adequately correlates the data for motored operation. The extension of this motored correlation to fired operation demonstrates the need for instantaneous local gas velocity and temperature data.