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The farm tractor industry went through some robust years of expansion in the 1970's followed by a rapid decline in the 80's. Demand models were developed to explain new farm tractor sales over the 1953-92 time period based on conditions in the agricultural economy.

The performance and microstructural behavior of several bearing steels tested in radial ball bearings were interpreted in terms of their microstructural alterations, residual stress and resistance to tempering. The bearings were fabricated out of 52100, M-50, and M-50 NiL steels and tested under identical conditions: a radial load of 1111 kg to produce a 3.62 GPa maximum Hertzian contact stress and a speed of 3 000 rpm to produce a calculated lambda ratio of 5.5. The plastically deformed region below the ball track surface of bearings which had run for extended periods was examined metallurgically and measurements were made of the hardness and circumferential residual stress. The 52100 steel bearings exhibited a white-etched microstructure in the softened worked region. The M-50 developed much less plastic flow without work softening, and the M-50 NiL exhibited the least microstructural alteration.

Two kinds of optical methods for the measurement of the temperature and concentration distribution in combustion chambers by means of the real-time laser holographic interferometry are presented in this paper, which are respectively the one-wavelength laser holographic interferometric technique and the two-wavelength laser holographic interferometric technique. The basic measurement principles of these laser holographic interferometric techniques, the characteristic features of their optical arrangements, the experimental device and testing procedure, and the formula of evaluation of holographic interferograms are described in detail.

The paper deals with the existing Diesel nozzles optimisation of the conventional injection system pump - high pressure pipe - nozzle. The aim of the optimisation is to increase the injection rate of the nozzle by 9 %, lower the fuel consumption and reduce the emissions of the engine. Existing and optimized nozzles should feature the same inlet pressure, i.e. the same load on the pump allowing that the same pump may be used also for the redesigned nozzle. Redesigned was the tip of the nozzle. The nozzle was optimized by computer simulation. The prototype of the redesigned nozzle was then tested on the test stand and in the four - stroke air - cooled engine according to the 13-mode ECE R49 cycle. Explained is also the influence of fuel injection parameters on engine performance and emission. All test results are presented in the paper.

Results of three-dimensional steady flow calculations are compared with existing pressure and velocity-measurements of two manifold-type junctions. The junctions consist of a main duct and a side branch, both with the same rectangular cross section, with the side branch joining the main duct at an angle of either 90 or 45 degrees. Both combining and dividing flow configurations are considered for different total mass flow rates and different side-branch-to-main-duct mass flow ratios. One objective of this investigation was to assess the effects of numerical differencing scheme and mesh refinement on solution accuracy, and both parameters showed strong influences on the computed results. It is shown that calculations should be made with the highest possible level of numerical accuracy and grid resolution in regions of flow recirculation. Comparisons of computed and measured velocities, static pressures, and flow loss coefficients are presented in this paper.

Smoothed Particle Hydrodynamics (SPH) is a numerical method that solves the Lagrangian, conservative equations of mass, momentum, and energy without using a computational grid. In the past, SPH has been used to solve problems of astrophysics, hypervelocity collisions, and explosions. This work has extended the application of SPH by solving problems involving inviscid, compressible aerodynamic flow. New boundary conditions were developed, so SPH could solve these types of problems. This paper will provide a short history of SPH, an introduction to the method, discuss the transformation of the governing fluid equations into the SPH formulation, and present several aerodynamic test cases. The power of SPH is that it requires no computational grid. This feature may significantly reduce the time required for the engineer to calculate computational solutions or may simplify the numerical techniques used to solve complex problems, such as moving body problems.

Improvement of the aural nondetectability range and crew compartment noise reduction have become critical factors affecting battlefield survivability of combat vehicles. A Detroit Diesel research program, funded by the United States Navy David Taylor Research Center, has documented the acoustical signature of a Light Armored Vehicle (LAV) under a variety of operating conditions. United States Army Military Standard 1474C criteria were used to define the one third octave aural nondetectability limits of the LAV. Based on a power train noise source analysis, experimental noise control measures were fabricated and tested on the LAV. Preliminary results suggest passive and active noise treatments have substantially reduced the acoustical signature of the LAV.

We present preliminary results from a study of the ability of various turbulence models to predict airfoil stall angle, as compared with one of the few modern data sets, from tests of the Aerospatiale airfoil AS240 in the ONERA wind tunnel of Fauga, France [1,2]. We first compared the Chien k - ε model [3], the Wilcox k - ω model [4], and the most recent version of the Launder-Reece-Rodi Reynolds-Stress Transport Model (RSTM) [5], in a boundary layer in zero pressure gradient. The k - ω model and the RSTM models were chosen for the airfoil calculations.

Stringent standards for the emission of particulate matter by heavy duty diesel engines will come into effect in the nineties in the US and are anticipated to come into effect in the same period in W-Europe and in Japan. This has lead most of the manufacturers to intensify the evaluation of exhaust aftertreatment devices. Although particulate filtering systems proved to be valuable in limited fleet applications, the general introduction did not take place because of complicated and limited durability regeneration. Flow-through catalysts which were introduced for passenger cars in 1989 drew a lot of attention for potential heavy duty diesel applications. In this paper the major parameters affecting the performance of these flow-through catalysts and the particularities related to heavy duty diesel application are outlined. The parameters deal with the fuel sulfur content, the test cycles applied, the catalyst formulation and washcoat composition.

Emergency Diesel Generators are used in the nuclear industry for stationary stand-by power in order to safely shut down a reactor unit in the event of loss of off site power. Therefore, a high diesel engine reliability and availability must be maintained. Engine turbochargers often experience operating failures resulting in extended down time and costly repairs. Improved turbocharger vibration testing using time synchronous averaging is one method for evaluating the operating condition of a turbocharger. Typical vibration collection methods result in the turbocharger vibration being masked by the high background noise associated with the reciprocating nature of the engine. Time synchronous averaging reduces the background noise and allows accurate measurement of the 1x RPM component and harmonics of the turbocharger. Trends of the turbocharger vibration may then be established for diagnostic purposes, giving the analyst another tool for improving engine reliability and availability.

A study was initiated to determine how to increase the fatigue strength of gray iron cylinder blocks. The approach was to determine what combination of metallurgical properties and foundry processes would yield the highest fatigue strength while maintaining the castability necessary for these complex castings. This study, unlike much of the literature available on fatigue strength in gray iron, was conducted using hundreds of castings and thousands of test bars. A baseline data base was established. This information was used to determine which factors would be most likely to effect the fatigue strength. An experiment was designed to determine how the foundry processes and the metallurgical factors interacted with more than twenty-five response variables.

Post-treatment of diesel exhaust was studied on a laboratory scale, using a reactor to simulate the post-combustion of soot collected inside a monolithic particulate trap. A parametric study of the trap regeneration was carried out. A periodic hydrocarbon injection system was developed to assist the catalyzed trap regeneration. This technique led to the trap regeneration with a temperature of the entering gas of 150°C, which is very low. An optimization of the injection process allowed one to minimize the injected amount of hydrocarbons and to have good control of the trap temperature. Another advantage of the hydrocarbon injection is to provide good conditions for reducing NO in an oxidizing atmosphere (10% O2). The importance of the hydrocarbon content was pointed out by a parametric study of NO conversion under a wide range of hydrocarbon concentrations (1000 ppm to 2.5% in CH4 equivalents).

In underground noncoal mines the emission of nitrogen dioxide (NO2) in the exhaust of a diesel engine is more important than the emission of nitrogen oxide (NO) because of the much lower permissible exposure limit for NO2. Consequently, the tendency of aftertreatment devices such as oxidation catalytic converters (OCCs) to oxidize NO to NO2 is counterproductive. The U.S. Bureau of Mines (USBM) is investigating the effects of OCCs upon NO2 emission by using a Fourier Transform Infrared (FTIR) exhaust gas analyzer to compare the concentration of NO2 in diesel exhaust upstream and downstream of the OCC. We find that some OCCs increase the concentration of NO2 much more than others, and that over some temperature ranges the aftertreatment results in an apparent decrease in NO2 concentration.

Many of the materials which have been developed for use as particle filters in the exhaust of diesel engines have characteristics which give rise to significant problems in practical use. Due to its special characteristics, it is shown that SiC is very well suited for use as the base material for particulate filters. The physical and thermal properties of porous SiC substrate material as applied to diesel particulate filters have been determined and are presented. Experimental results from several types of filter regeneration processes in exhaust gas systems confirm the improvements in the area of thermal load and reduction in temperature level during regeneration. The reduction in temperature during regeneration is shown to be consistent with the high thermal conductivity of SiC.

In the early design stage a 16-cylinder V-engine is optimized with respect to its vibrational and acoustic behavior. The objectives of the development are: (1) to minimize vibrations of the crankcase with special focus on the structure-borne noise transmission via the engine mounts, and (2) in this context, to identify the appropriate locations for the engine mounts. The NVH behavior of the engine structure is simulated using the Finite Element Method (FEM). The dynamic FE-model of the engine is excited via synthesized cylinder pressure force spectra. The corresponding vibrations of the sound emitting surface are calculated, thereby revealing structural weaknesses. By calculation of the crankcase modal vibrations, the noise relevant modes are identified. Based on these results the influence of structural modifications on the NVH behavior is predicted.

The U.S. Bureau of Mines (USBM) and Diesel Controls Limited are evaluating a new diesel emission control system on an underground mine vehicle. The system is a catalyzed ceramic wall-flow diesel particulate filter (CDPF) combined with an oxidation catalytic converter (OCC). It is the first installation in the U.S. of a CDPF on a mining vehicle with a turbocharged engine at a high altitude mine, and the first installation of both a CDPF and an OCC on a mine vehicle. This paper describes the design and installation of the system on the load-haul-dump (LHD) vehicle. The results of screening tests conducted by the USBM are also given. The screening tests were conducted to determine if the device's particulate collection efficiency, regeneration temperature, and effect on gaseous hydrocarbon (HC) and carbon monoxide (CO) emissions changed over the period at was being used. The system was removed from the LHD and evaluated in the laboratory after operating for 308 and 1200 hours.

A novel design of an air-gap insulated piston has been proposed which is expected to give a longer life compared to the past designs and lower heat transfer there by increasing its crown temperature. Also it is light weight. The basic design of the piston, where the crown is separated from the body of the piston through a thick composite gasket. The crown and the piston base are fitted together by an interference fitting and locked by oval shaped rivets. A steady state two dimensional thermal analysis is done on the piston for the following five cases using FEM: Aluminum piston single piece as reference, aluminum crown with thick composite gasket and air-gap with aluminum base, composite crown and air-gap with aluminum base, all composite piston without air-gap and all composite with air-gap. Constant temperatures are assumed at gas, liner and oil boundaries of the piston. Also the film coefficients on the piston boundaries are kept constant for all the cases.

During engine durability testing of a large diesel engine, several pistons were found to have experienced fatigue cracks along the combustion bowl edge directly over the pin bores. In order to determine the optimum design solution to this piston combustion bowl edge cracking problem, the performance of several power cylinder assemblies have been investigated to determine their effects on piston combustion bowl edge stresses. The power cylinder design variables examined in this analysis were piston skirt section thickness, piston compression height, pin inner and outer diameters and connecting rod end designs (Tee-Pee vs. straight). A finite element analysis of each power cylinder assembly was performed to ascertain the stresses existing on the piston combustion bowl edge. This finite element analysis found combustion bowl edge stresses from the thermal expansion effects only loading as well as those from the combined thermal expansion and combustion pressure loading.

The design and analysis of most engineered systems involves many and sometimes diverse technical disciplines. For example, in the design of a fluid power system, the input to the system is usually some type of prime mover. In addition, the output may include gears, linkage, etc. The output may be used in a feedback circuit which will normally encompass instrumentation, logic elements, and controllers. In order to evaluate the total performance of such systems analytically, a software package must be available which can unify the interactions of these diverse components. This paper will present a new computer program which will unify hydraulic, pneumatic, electronic, and mechanical components permitting the analysis of complete engineered systems on a P.C. Several example systems will be shown which originate in actual machinery designs. These example systems will be simulated and output type information will be presented.

Determination of flow distribution is important in many types of fluid power machines. The life and proper operation of engines, transmissions, and fluid power equipment is dependent on satisfactory flow distribution of oil in the passages of the circuitry. Use of the hydraulic ohm provides a simplified and accurate method for determination of flow distribution and associated pressure values. The method provides a rapid solution and eliminates the need for the iterative type procedures commonly used.