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Three-dimensional large eddy simulation (LES) has been conducted for a diesel spray flame using KIVALES which is LES version of KIVA code. Modified TAB model, velocity interpolation model and rigid sphere model are used to improve the prediction of the fuel-mixture process in the diesel spray. Combustion is simulated using the Eddy-Dissipation model. CIP method was incorporated into the KIVALES in order to suppress the numerical instability on the combustible flow. The formation of soot and NO was simulated using Hiroyasu model and KIVA original model. Three different grid resolutions were used to examine the grid dependency. The result shows that the LES approach with 0.5 mm grid size is able to resolve the instantaneous spray with the intermittency in the spray periphery, the axi-symmetric shape and meandering flow after the end of injection as shown in the experimental results.

Generally, it is well known that road noise generated by vibration from automobile tires and suspensions can be reduced by changing the stiffness of the rubber mounts installed in the suspension systems. Such stiffness, however, is rarely changed to avoid riding discomfort and so on. In this paper, a stiffness optimization method for suspension system rubber mounts that reduces road noise, and improves riding comfort as well, is presented. In the process, Road Noise Contribution Analysis (RNCA) is applied to the target vehicle to specify the major factors of road noise. Furthermore, the suspension system of the vehicle is investigated by Sensitivity Analysis using Measured FRF data (SAMF) to identify the optimal stiffness combination of rubber mounts. As a result, an effective stiffness combination of two mounts is specified to reduce road noise and to improve riding comfort.

Recently, the development stage of agricultural vehicles such as the tractor has focused on new demands to improve the cabin environment. Especially the ride comfort has become increasingly important. For this purpose, rubber bushes have been installed the tractor to reduce road vibration to the driver in the cabin. However, this device does not sufficiently suppress vibration. This paper presents a method of vibration reduction that installs a semi-active suspension in the lateral and vertical directions at the cabin mount position of the tractor. In numerical simulation, the tractor model installed with a semi-active suspension is superior in performance to the conventional tractor model.

Tiny (hair-like) cracks initiated around small holes in the flange of one-piece brake discs were observed at an overloading condition. Thermally induced cyclic stress strongly affects the crack initiation in the brake discs. In order to show the crack initiation mechanism, the temperature distribution at the flange was firstly measured. The temperature distribution under overloading was analyzed by using the finite element method. Based on the experimental and calculated results, the crack initiation mechanism for one-piece brake discs at the very severe braking condition was explained. In addition, the effective methods are suggested for reducing the initiation of tiny cracks around the holes.

This paper describes a steady vibration of an engine supported by rubber and hydraulic mounts at a relatively low frequency range, assuming an engine is a rigid body. We identify dynamic characteristics of a hydraulic mount with respect to frequency and amplitude. The equation of motion is solved numerically by the Newton-Raphson method, treating the mount characteristics as functions of frequency and amplitude. The excitation test to simulate an engine shake and an idling vibration was performed using a mass block instead of an actual engine. During the engine shake, we observed that the amplitude dependency of hydraulic mounts strongly influences the vibration, while idling, we investigated rolling vibration especially for the case where the torque axis does not pass through the engine's center of gravity. The theoretical predictions agree closely with the experimental results in both engine shake and idling vibration tests.

An advanced numerical model is proposed to analyze the power transmitting mechanisms of a CVT using a metal V-belt. By using the present model, forces acting on the belt are well estimated not only at steady states but also during transitional states where the speed ratio is changing. The numerical results show that blocks are in compression in both strands when the speed ratio is rapidly shifted. A complementary model is also developed to analyze the load distribution among bands which form the ring. The load distribution in the ring is governed by the difference in coefficients of friction among elements.

The purposes of this study are to clarify the atomization mechanism, the change over time in droplet size distribution, and the change in spray characteristics dependent on back pressure on diesel fuel spray. Diesel spray injected into a quiescent gaseous environment under high pressure is observed by taking direct microscopic photographs varying the moment of exposure, the back pressure, and the ambient density. The results show that the mechanism of spray atomization is divided into 4 processes, and spatial distribution of breakup droplets and a droplet volume rate are assessed for the whole spray region. Total and local distributions of droplet size are expressed by empirical equations as a function of time elapsed from the moment of injection. It is confirmed that the uniformity of the distribution, Sauter mean diameter of droplets, and droplet production rate change with time. Mean droplet diameter is further described in relation to the pressure drop and the ambient density.

In this study, the authors analyze the concentration distribution of an evaporative spray mixture with LIEF (Laser induced exciplex fluorescence) method, which is a type of optical measurement. LIEF method is one of the optical measurements for obtaining the spray concentration distribution for separating vapor/liquid phases based on the fluorescence characteristics. In this paper, a quantitative concentration distribution analysis method for wall impingement spray in heterogeneous temperature field has been proposed. Then, a series of experiments were performed in varying injection pressure and ambient density. As a result, a two-dimensional concentration distribution was obtained for the free spray and wall impingement spray.