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The influences on fuel efficiency of viscosity difference and friction modification by colloid friction modifiers in motor oil were examined separately and in combination in a series of automobile track tests using EPA test procedures. The results of this work demonstrated the following: 1. In this test program, simply reducing the viscosity of multi-grade engine oils did not produce consistent, statistically significant fuel economy benefits. 2. The incorporation of a colloid friction modifier in reduced viscosity multigrade oils produced consistent and statistically significant improvements in fuel economy over those same reduced viscosity multigrade oils without colloid friction modification. 3.

Several polymer-containing oils have been studied in a journal bearing rig under hydrodynamic lubrication conditions. For shear rates up to 2.5 x 105 s-1 and oil film thicknesses down to 2 μm, these oils showed the same behaviour as polymer free oils. In a second series of experiments, the bearing was provided with a suitable lining and experiments were carried out under boundary lubrication conditions. Bearing wear could be determined by weighing of the bearing shells, and the results obtained show that for Newtonian lubricants wear increases markedly with decreasing viscosity. The influence of the performance package was demonstrated by two SAE 30 grades. A decrease in wear of about 60 % was effected by a change of the performance package.

More exact simulation of engine in-service operating conditions by accelerated development test program improvements-T700/F101/F404/CFM56/CF6-are reviewed for lessons learned towards earlier identification/solution of engine life extension problems. Improved design features, improved analysis and test simulation of mission cycles, improved component test techniques and, in general, increased emphasis on demonstrating required minimum service life prior to Production are briefly discussed. Possible future direction of these efforts is indicated for consideration in General Engine Specification revisions.

This paper was made up from the prepared discussions and author closures of the Symposium Papers. The Symposium was held at Cobo Hall, Detroit, Michigan on March 1, 1978 as part of the SAE Congress and Exposition. The nine papers presented at the Symposium were bound in a booklet. These discussions and author closures provide a supplement to the bound papers, SAE SP-429 and ASTM STP 621-52.

Two advanced techniques to improve the process of designing and developing high technology gas turbine engines are being evaluated and implemented at the Pratt & Whitney Aircraft Government Products Division: Improved Design Verification System Accelerated Mission Endurance Test Techniques. These techniques are not new, but they have been significantly improved and strengthened in the past few years by the development of new high technology instrumentation and sophisticated computerized design prediction methods. These tools are aimed at providing improved product reliability during the early operational phase and reducing ultimate cost of ownership for the user.

An improved approach to the development and qualification of aircraft turbine engines has been developed by the Navy. The approach places emphasis on durability testing throughout the engine development program. This testing is intended to assure that structural requirements have been achieved upon the introduction of new engines into service. The approach utilizes three different types of durability tests each of which is intended to address a separate aspect of the overall durability problem.

An initial wind-tunnel test was conducted to investigate the aerodynamic interactions between a propeller slipstream and a supercritical wing at transonic Mach numbers. The primary independent variables examined included Mach number, wing lift coefficient, and slipstream Mach number and swirl. The interference effects were found to be weak functions of free-stream Mach number, wing lift coefficient, and slipstream Mach number; swirl was found to have a significant effect. At a free-stream Mach number of 0.8 and a lift coefficient of 0.5, incremental drag results for 7° of swirl (upwash inboard) and a slipstream Mach number of 0.87 indicate a penalty equivalent to a 0.024 loss in propeller efficiency. However, at 11° the drag increment was favorable and was equivalent to a 0.032 increase in propeller efficiency. Wing pressure data indicated the effects of the slipstream were essentially restricted to that section washed by the slipstream.

Studies have established that advanced turboprop (prop-fan) equipped aircraft will reduce fuel consumption by 15 to 30 percent compared to aircraft equipped with high-bypass turbofan engines of equivalent technology. A reduction in direct operating costs of approximately 10 percent has been identified for commercial aircraft as well as approximately a 20 percent lower gross weight airplane for long endurance military missions. The prop-fan propulsion system is being investigated as part of the NASA Aircraft Energy Efficiency program which includes both analytical studies and experimental tests. The experimental work encompasses performance and acoustic wind tunnel tests on several prop-fan models. The prop-fan technology status is reviewed in the major areas of performance, installed effects, cabin noise, blade structure and maintenance cost. Also, future activities required to complete the technical validation of prop-fans are described.

The goal is to design an integrally cast wheel with blades which can be produced from high volume production tooling. An automated procedure is described to determine the optimum radial orientation, or “stacking,” of turbine rotor blade sections to give a design which satisfies both high production manufacturing and rotor structural requirements. High production manufacturing requires that the spaces between blades be pulled away from the wheel in a generally radial direction to release the wax replica of the wheel from the tooling. Structural requirements are expressed in terms of bending stress constraints. A pullability index is defined to indicate the amount of interference to be encountered in removing the tooling. This index is optimized with respect to the direction of removal of the tooling. Bending stress requirements are simultaneously satisfied.

The Turbine Design System (TDS) is a time sharing computer system developed for preliminary design and performance evaluation of axial flow turbines having up to ten stages. TDS is an interactive, modularized system incorporating aerodynamic, heat transfer and structural analyses in a contiguous arrangement. Each task oriented module addresses one major facet of the design process. This paper discusses the overall system philosophy and organization, the input/output data flow, the tasks performed, and the functional utilization of the system. Selected results of a sample case are shown.

Presently, the different methods available to measure the viscosity of fluids at low temperature with the Brookfield viscometer do not give entire satisfaction because of their low precision. A working group set up by the Technical Committee “Transmission Lubricants” (T.L.T.C.) of Groupement Français de Coordination (G.F.C.), member of C.E.C.*, ran different tests which led to the proposal of a new method. This new procedure for measuring the Brookfield viscosities includes the following improvements : shortened test duration better precision, and was adopted by C.E.C. as tentative method under the number CEC L18-T76.

The author reflects on his 30 years experience in diesel combustion and related research. Philosophical approaches to problem solving are illustrated by some of the earlier work in which the author was personally involved. The problems facing the diesel today, particularly from a combustion point of view, are reviewed and areas for research effort are highlighted.

This paper summarizes and analyzes data that have led to a proposed generalized Brookfield procedure for measuring the low temperature, low shear rate viscosity of automotive lubricant fluids. The data were collected between 1974 and 1977 by ASTM Committee D-2, Research and Development Division VII, Brookfield Viscometry Task Force in cooperation with the Institute of Petroleum, the Groupement Francaise de Coordination, and the National Research Council of Canada. The sources of error in the generalized Brookfield procedure are examined in detail. A system based on the known viscosity-temperature function of Newtonian reference fluids is proposed for estimating error magnitudes from existing cooperative data. Application of these estimated error magnitudes to engine and gear oil data produced repeatability and reproducibility estimates that are functions of viscometer rpm for non-Newtonian products. Viscometer rpm is shown to be a critical test parameter at low temperature.

This paper reviews the work of ASTM Research and Development Division VII during 1973-77 related to the low-temperature flow characteristics of automotive gear oils. Phase I showed that the Canadian channel point test was superior to the U.S.A. method in operability and discrimination between oils, although some modifications to the Canadian method were recommended. Phase II concerned establishing reference oils based on tests in cold full-scale axles, and using these reference oils to evaluate laboratory tests for determining and specifying cold fluidity of gear oils. Brookfield viscosity proved most suitable, with channel point and pour point being much less favorable.

The paper presents the results of a gas station survey in the Spring of 1978 which attempted to estimate the incidence of the misfueling of vehicles. Misfueling was defined as the use of leaded gasoline in cars designed to use unleaded gasoline. The data was collected by on-site observers in seven major Canadian cities. In addition to fuel type used, information on the frequency of pump nozzle substitution and fuel inlet tampering are compiled and presented. Conclusions on the importance of this problem in the control of emissions from cars are developed.

A fundamental thermodynamic model of the complete spark-ignited, homogeneous charge engine cycle has been used in several parametric analyses to predict the effects of engine design and operating alternatives on fuel consumption and emissions of NOx and unburned hydrocarbons (HC). The simulation includes sub-models for wall heat transfer, NOx and HC emissions, and the engine breathing processes. This work demonstrates the power and utility of a comprehensive engine simulation by presenting several independent parametric studies that were carried out in response to genuine engine design and/or operating strategy questions. Included in this compilation are the effects of cycle heat loss, exhaust port heat loss, combustion duration, and charge dilution (EGR and/or lean air-fuel ratio). In addition, the influence of the design variables associated with bore-stroke ratio, intake and exhaust valve lift, and cam timing are considered.

Direct cylinder injection for hydrogen-fueled piston engines was studied experimentally with an ASTM-CFR engine. An injection scheme was devised for which the combustion occurs during the period of hydrogen injection so that little unburned hydrogen accumulates in the cylinder. This scheme should preclude flashback and preignition, and lowers the rate of cylinder pressure rise to acceptable levels. The potential of hydrogen as a low pollution fuel was investigated by comparing the NOx emissions from the same engine operated on hydrogen and hydrocarbon fuel. NOx emissions for hydrogen are very low provided the equivalence ratio is less than 0.5, and provided the hydrogen and air are well mixed. For equivalence ratios greater than 0.5, NOx emissions for hydrogen fuel were higher than for hydrocarbon fuel. With hydrogen injection, indicated mean effective pressure was varied between 0.07 MPa and 0.78 MPa without intake air throttling.

A test program was conducted with a carbureted 2.3-liter engine in which a map of engine operating conditions over which intake manifold wall films of appreciable magnitude exist was defined on the basis of visual observations. It was found that the largest maldistributions of fuel/air ratio among the four cylinders of the engine occurred during operation at conditions characterized by the presence of extensive fuel puddles on the intake manifold floor. However, it was also found that while the intake manifold fuel films and puddles could essentially be eliminated by heating the manifold floor, the fuel/air ratio distributions among cylinders under such conditions were virtually identical to those measured under conventional operating conditions.

Emission control programs for automobiles have now been in existence for almost two decades in some jurisdictions. In addition, the approach to regulation and enforcement varies from country to country thus creating a large array of policy alternatives which can be evaluated. This paper attempts to review the strenghts and weaknesses of the major control programs around the world and evaluate the costs and effectiveness of the existing standards in reducing emission levels. The data that forms the basis for this paper is from an OECD report on the subject prepared by the author in 1977 and contains data from the ECE, Japanese, US, Canadian, Swedish and Australian automotive emission control programs. A method of comparing the major test standards is presented in order that the standards can be quantitatively and qualitatively related to each other.

Studies have been conducted which illustrate the excellent overall performance of a synthesized passenger car engine oil during greatly extended drain intervals. These studies were conducted primarily with automobiles manufactured in the U.S. and with typical U.S. service. Supporting data are presented in areas of engine cleanliness, engine wear, and lubricant stability from several types of service conditions including heavy duty taxicab and police car operations as well as typical everyday consumer driving. Information is also provided from a high mileage test using the EPA durability cycle. These field test results correlate well with extended duration API SE sequence data.