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The end-gas auto-ignition and associated pressure wave generation in a premixed gas with a spatial distribution is numerically investigated. This study assumes that the auto-ignition phenomenon in the end-gas of PCCI combustion, a next-generation combustion method which is expected to achieve both low fuel consumption and low emissions at a high level. Detailed numerical analysis considering the chemical kinetics on the one-dimensional compressible fluid flow with high spatial and time resolution was performed to clarify the detailed phenomena of the auto-ignition and onset of the pressure wave and its propagation in the end-gas. Followings are results. (1) The pressure wave generations related with the auto-ignition in the end-gas is categorized into two types. The cases that the auto-ignition velocity, which is the localized auto-ignitive propagation velocity relative to the unburned mixture, exceeded the local sound speed, or not.

A cooling fan is one of the primary components affecting the cooling performance of an engine cooling system. In recent years, with the increase in electric vehicles (EVs) and hybrid vehicles (HVs), the cooling performance and noise level of the cooling fan have become very important. Thus, the development of a low-noise fan with the same cooling performance is urgently required. To address this issue, it is critical to find the relation between the performance of the fan and the flow structures generated around it, which is discussed in the present paper. Specifically, a computational method is employed that uses unsteady Reynolds-averaged Navier-Stokes (URANS) coupling with a sliding mesh (SLM). Measurements of the P-Q (Pressure gain-Flow rate) characteristics are performed to validate the predictive accuracy of the simulation.

This study investigates the reduction of the Blade Passing Frequency (BPF) noise radiated from an automotive engine cooling fans, especially in case of the fan with an eccentric shroud. In recent years, with the increase of HV and EV, noise reduction demand been increased. Therefore it is necessary to reduce engine cooling fan noise. In addition, as a vehicle trend, engine rooms have diminished due to expansion of passenger rooms. As a result, since the space for engine cooling fans need to be small. In this situation, shroud shapes have become complicated and non-axial symmetric (eccentric). Generally, the noise of fan with an eccentric shroud becomes worse especially for BPF noise. So it is necessary to reduce the fan BPF noise. The purposes of this paper is to find sound sources of the BPF noise by measuring sound intensity and to analyze the flow structure around the blade by Computational Fluid Dynamics (CFD).

Osaka University Formula Racing Club (OFRAC) [1] won the first prize in the 8th Student Formula SAE Competition of Japan [2] organized by the Society of Automotive Engineers of Japan (JSAE). The technical developments, especially on the power train system, acted very important roles for this winning. Three technical developments were introduced to meet the machine concept “Get more performance at corner exit.” They are; (1) Dry sump lubrication system to reduce the height of the center of gravity (C.G.), (2) Rotary throttle valve system to get more power and (3) Semi-automatic shift up assist system to reduce the loss of traction force during shifting up. In this paper, these unique technologies, which were originally student-developed, on the power train of our championship car, ‘OFRAC Naniwa-X,’ are focused [3].

A fuel supply system and characteristics of CVT (Continuously Variable Transmission) were changed to get better dynamic performance of an engine and axle output, respectively. A fuel supply system were changed from carburetor to fuel injection to improve an engine power. Engine power and torque with fuel injection system were higher than that with carburetor system by approximately 19% and 21%, respectively. In the power transmission system, the effect of spring constant of pressure spring and weight of flyweight on engagement speed and shift speed were investigated to improve an acceleration performance. Engagement speed and shift speed were higher as spring constant of pressure spring increases and weight of flyweight decreases, respectively.

Recently the programs for the development of the second generation SST are presented by several industries. On the aerodynamic design of SST, it is very important to improve a cruise L/D. So we have investigated the effects of three typical drag reduction technologies, namely, the application of a suitable wing planform, a warped wing and an area-ruled body, by using both experimental and numerical approaches. The obtained results are as follows. The increment of the cruise L/D is about 0.1 for an arrow planform, 0.6 for a warped wing and 0.5 for an area-ruled body. So we deduce that our SST configuration has the L/D of about 8.6 at cruise Mach number 2.0, including some corrections on the Reynolds number, fuselage volume, etc.. And applying our Navier-Stokes calculation code for our testing models, we find that the CFD code is very useful to predict the characteristics at design conditions