鈴木 隆

<p> The present study conducted the derivation of the empirical equation in terms of the heat transfer phenomena at the intake manifold of internal combustion engines and the implementation of its equation to 1-D engine simulation. The derived equation allows to calculate the Nusselt number at the intake system, which causes to predict the mass flow rate of intake air into the cylinder accurately, ultimately improving the fuel consumption by controlling the auto-ignition timing. The empirical equation was developed based on the Colburn equation, taking into consideration of the effects of the thermal boundary layer development and the intermittent air flow induced by the opening and closing of intake valves. Compared with the experimental data, the average errors of the Colburn equation and the empirical equation were estimated to be 91.1% and 2.7%, which gives to improve the prediction accuracy of the Nusselt number by deriving the empirical equation. The equation was then implemented in 1-D engine simulation and compared to the results of the Colburn equation, revealing the maximum and average intake air temperature differences of 11.4 K and 2.7 K, respectively.</p>

<p>For improvement of thermal efficiency of diesel engines, it is effective to control the fuel injection by using the model-based control (MBC) on the ECU (on-board) with cycle-by-cycle calculation. The authors previously developed an on-board in-cylinder wall temperature prediction model and wall heat transfer prediction model for MBC. For the validation of the developed models, the present study measured the time evolution of local wall temperature and pressure in the combustion chamber and calculated wall surface heat flux and evaluated the errors of heat loss results obtained from model. Also, the polytropic index prediction model was evaluated using the result of in-cylinder pressure. As a result, it was confirmed that heat loss results during compression and expansion strokes show 1.3% errors and polytropic index prediction model shows 0.1% errors comparing with experiment data.</p>

In the past two decades, internal combustion engines have been required to improve their thermal efficiency in order to limit hazardous gas emissions. For further improvement of the thermal efficiency, it is required to predict the mass of intake air into cylinders in order to control the auto-ignition timing for CI engines. For an accurate prediction of intake air mass, it is necessary to model the heat transfer phenomena at the intake manifold. From this intention, an empirical equation was developed based on Colburn equation. Two new arguments were presented in the derived formula. The first argument was the addition of Graetz number, where it characterized the entrance region thermal boundary layer development and its effect on the heat transfer inside the intake manifold. As the second argument, Strouhal number was included in order to represent intake valve effect on heat transfer. This study compared experimental data with the present empirical equation, and average error was estimated to be 3.1%, which was significantly improved in comparison with the Colburn equation. Furthermore, derived empirical heat transfer equation was implemented to the intake manifold model of a diesel engine in 1-D engine simulation. The study confirmed the influence of the heat transfer phenomena, and its importance to intake air. At IVC, temperature difference between Colburn equation and derived equation was calculated to be 3.8 K. This corresponded to an advanced auto-ignition timing by 0.78 deg. CA, which gives an estimated improvement of 0.22% when evaluating both the thermal efficiency and CO2 emission.

<p>Internal combustion engines have been required to improve the thermal efficiency and reduce the pollutant emission, and the previous studies were developed by controlling the air-to-fuel ratio and reducing the pressure fluctuations. For further improvement of the thermal efficiency, it is expected to model the heat transfer phenomena at the intake system and predict the air mass flow rate into the cylinder, which causes to keep the stoichiometric air-to-fuel ratio and improve the fuel consumption. The present study experimentally developed the empirical equation of the heat transfer at the intake system. This was based on Colburn's equation considering the development of the thermal boundary layer and the unsteady heat transfer phenomena, which was expressed by using the Reynolds, Graetz and Strouhal numbers. Compared with the experimental data and the present empirical equation, the maximum and average errors were estimated within 10.5% and 3.1%, respectively.</p>

Gasoline engines have been required to improve the thermal efficiency and reduce the pollutant emission, and the previous studies were developed by controlling the ignition timing and keeping the constant air-fuel ratio. For further improvement of the thermal efficiency, it is expected to reduce the pressure fluctuations due to the combustion per cycle, which causes to generate the stable combustion field and improve the fuel consumption. Since the pressure fluctuations due to the combustion are significantly affected by the ratio of the residual gas in the cylinder, the present study proposed the method to estimate the ratio of the residual gas, which is defined as the mass ratio of the residual gas and the air-fuel mixture into the cylinder, by using the combustion pressure, and developed the methods to reduce the pressure fluctuations considering the ratio of the residual gas by controlling the ignition timing. Under the experimental condition of the large ratio of the residual gas, it was found that the fluctuations of the indicated mean effective pressure was reduced to more than 20% by using the developed methods.

<p>This study presents an experimental optimization of the thermal efficiency of a short-stroke small engine with a supercharger, which has the advantage of high engine power and the shortcoming of increased loss of cooling from the combustion chamber walls. This shortcoming is responsible for the reduction of the net thermal efficiency. For improving the thermal efficiency, the present study considered using the lean mixture combustion, and optimized the valve lift, the valve overlap angle, the air-fuel ratio (A/F), the ignition timing, the boost pressure, and the surface treatment. Firstly, the valve lift and the valve overlap angle were changed, which lead to the reduction of the blowby and the blow-back gas. We investigated the effects of the A/F and the ignition timing on the engine torque and the brake specific fuel consumption rate (BSFC), and these results showed that it was possible to improve the BSFC, although the engine torque decreased along the overall engine speed range. Secondly, for the improvement of both the engine torque and the BSFC, we optimized the relationship between the boost pressure and the A/F and adapted the surface treatment, which lead to the reduction of the pumping and the friction losses. From the above optimizations, the averaged engine torque, the averaged BSFC and the maximum net thermal efficiency were improved by 6.3%, 10.9% and 38.8%, respectively.</p>

For further development of the thermal efficiency of SI engines, the robust control of the air-fuel ratio (A/F) fluctuation is one of the most important technologies, because the A/F is maintained at the theoretical constant value, which causes the increase of the catalytic conversion efficiency and the reduction of pollutant emission. We developed the robust controller of the A/F, which is the method to change the fuel injection rate by using the feed-forward (FF) controller considering the heat transfer at the intake system. The FF controller was verified under transient driving conditions for a single cylinder, and the A/F fluctuations were reduced at approximately 84%.

Nowadays, cornering performance of FSAE (Formula SAE) cars are dramatically improved due to less mass, kinematic developments and tires. In such circumstance, under high speed conditions, aerodynamical devices work better. It had been decided to attach aerodynamical devices that consist of front wing, rear wing, diffuser (floor) and deflector for SR11 (Fig. 1, Table 1), a FSAE car developed by Sophia Racing (Japan). Fig. 1SR11Table 1Vehicle configuration of SR11 To start with developing aerodynamical devices, it had been assumed that how they work. Lap time simulation had been done with VI-car-realtime, which shows the laptime could be shorten by 2 seconds of 60 seconds for a usual FSAE endurance course with 60kgf at 60km/h downforce. Dragforce had been assumed to work well while once, it had been supposed to have a bad influence for laptime. The reason why it works well is at high speed, it works as extra braking force even without tires doesn't contact with ground or unfavorable load distribution. Then, 60kgf downforce was a target, while no target with dragforce. To maximize downforce, optimization for wing shapes with adjoint solver had been done. With these developments, 55kgf at 60km/h has been measured with load gauges, around 10% G for each lateral and longitudinal has been measured with G sensors. © Copyright @2013 SAE Japan and Copyright @ 2013 SAE International.

The paper reviews the experimental development of fuel economy of engine powering the 2012 Formula SAE single seat race car of the University of Sophia. The balance of high power and low fuel consumption is biggest challenge of racing engine. It was found that improving the efficiency of engine by supercharging as a way to achieve that. In order to adapt the supercharger for the engine, the important design points are below: It was found that intake air blow-by gas at combustion chamber is increased in low engine speed. To improve that, the valve overlap angle was changed to adopt supercharged engine and improve effective compression ratio. Typically the racing engine demands maximum torque for performance but that does not imply that the air fuel ratio should be rich than theoretical. The point is the maximum torque of the engine is proportional to the amount of air intake. Therefore, supercharged engine is possible to increase the supercharging pressure for bigger torque. But the base engine is not prepared for bigger torque, the damage of the engine was considered. In order to avoid engine breakage, the lean air-fuel ratio was used and maximum torque was controlled not to exceed an engine limit. The aim air fuel ratio was change by engine speed to get more flat torque performance, and improved the fuel consumption. © Copyright @2013 SAE Japan and Copyright @ 2013 SAE International.

1Many environmental problems, such as global warming, drain of fuel and so on, are apprehended in all over the world today, and down-sizing is one of the wise ways to deal with these problems. It is significant that a decrease of the engine power must not be produced by using a small displacement engine, so more efficient engine system should be designed to increase the torque with a little fuel. This study achieves an improvement of efficiency for mounting the super charging system on the small displacement engine. As a result, comparing a super charged engine and a naturally aspirated one to drive the same course and laps, fuel consumptions are 2547 [cc] and 3880 [cc], respectively, and an improvement of fuel consumption is 52%. Designing points to mount super charging system is introduced below. 1It can be forecasted that intake air blow-by gas at the combustion chamber is increased in low engine speed because engine for motor cycle is used. Therefore, the valve timing (cam profile) is changed.2Stress analysis and fluid flow analysis were done for the new intake chamber made by powder laminated casting. The sectional area of the new intake chamber is set to become gradually smaller, in order to increase the flow rate.3Inter cooler is adapted, because intake air compressed with super charger becomes hot and it causes a decrease of charging efficiency and an increase of the knocking of an engine.4The fuel injection map and the ignition timing map are optimized for changes above. These changes above made it possible to make higher torques for a wider range of engine speeds, and this leads to low fuel consumption. It is because that coming down torque peak and average engine speed reduce engine friction. In this way, the value of fuel consumption with super charger can be lower than the one with naturally aspirated. Copyright © 2011 SAE Japan.

The experiments were done in order to obtain the fundamental information that would be needed to build a physical model which expresses the heat transfer phenomena in the intake port model and manifold. In the experiments, the heating conditions and the period of the cyclic change of the gas velocity were changed as experimental parameters. In addition to those parameters, the Strouhal number was applied to express oscillating flow. As a result, the heat transfer in the experiments became clear, and the equations were obtained to show the Nusselt number using the Reynolds number, the Graetz number and the Strouhal number. Copyright © 2009 SAE International.

Temperature measurement experiments with intake port model were done to achieve the fundamental information on constructing physical model that expresses the heat transfer phenomena in the intake manifold and intake port. The experiments were done with steady airflow, and the size, shape, heating condition of the port model and mass flow rate were changed as experimental parameters. As the results, it was clear that the developing condition of velocity and thermal boundary layer had greater influence than the shape factor, and the coefficient and the exponent of the equation derived from the relationship between Nusselt number and Reynolds number had great difference from those of generally used Colburn's equation in undeveloped entrance region, but they got closer as developing boundary layer. Copyright © 2005 SAE International.

Measuring precise in-cylinder pressure traces of internal combustion engines is an important factor for estimating their performances. It is known that the actual pressure readings measured with piezoelectric pressure transducers have various forms of error. This paper is devoted to a study of compensation methods for reducing the errors caused by thermal shock. Numerical analysis was carried out for the error to derive the equations of error compensation using the actual pressure data. The results indicate that the error is corrected quite well with the obtained equations.

Measurement and analysis of burner flame spectrum with the biomass blended liquid fuel was done to investigate the combustion characteristics of biomass fuels. The experimental apparatus was mainly constructed of fuel vaporizing and mixing device, laminar flow burner, reflection spectroscope, and a digital camera. Four kinds of pure fuel and four kinds of blended fuel were used and the equivalence ratio was changed as the experimental parameter. As the results, it was obtained that the main radical luminescence existing in the flame, its changing tendency against the equivalence ratio, and the possibility of estimating the equivalence ratio with the ratio of luminous intensity of two different radical.

Temperature distribution as the flame propagated and contacted to the wall of the combustion chamber was measured by real-time holographic interference method, which mainly consisted of an argon-ion laser and a high-speed video camera. The experiment was done with a constant volume chamber and propane-air mixture with several kinds of equivalence ratios. From the experimental results, it can be found that the temperature distribution outside the zone from the surface of the combustion chamber to 0.1mm distance could be measured by counting the number of the interference fringes, but couldn't within this zone because of lacking in the resolution of the used optical system. The experimental results show that the temperature distribution when the heat flux on the wall increases rapidly and when the heat flux shows the maximum value are quite different by the equivalence ratio. Therefore, the temperature distribution when the heat flux shows the maximum is related with the lower temperature of ignition temperature. Copyright © 2004 SAE International.

Temperature distribution in the near wall region was measured by real time holographic interferometry and high-speed video camera. As a result, temperature distribution, within the region from the wall surface to 0.1mm distance, could not be measured, because of the lack of the resolving power of designed optical system. However, the temperature distribution of the other region was measured by counting the number of interference fringes. In addition, the great change of temperature distribution as the flame approached toward the wall was measured.

Since, we derived that the luminous intensity of C_2 radical and CH radical can be described as an exponential function of the combustion pressure from the previous research, it becomes possible that supplied equivalent ratio is estimated from the luminous intensity ratio of radical. But, before applying this research to the engine that runs under the high temperature, it is necessary to examine the effect of the temperature change of mixture. Therefore, we did an experiment by using the optical unit and the constant volume combustion chamber, which made temperature change of mixture in the combustion chamber. Through analyzing the experimental result, we had concluded that the radical luminescence ratio is not affected by the change of the temperature of the mixture.

The purpose of this study is to find the suitable working conditions of a Pressure Wave Supercharger (PWS) that is coupled to a gasoline engine experimentally. The working condition is validated by stationary measurements on an engine dynamometer. To achieve an easier system structure, it was examined to use the engine output for driving of PWS. As a result, it was confirmed that the engine coupled with PWS could be driven by making the ratio of the PWS rotor speed and the engine speed constant. Copyright © 2001 Society of Automotive Engineers, Inc.

The electronic controlled carburetor and ignition system has been developed. In accordance with various working conditions of the engine, the system adjusted corresponding control parameters air fuel ratio and ignition timing, therefore it could keep the engine working on the optimal conditions. Through analyzing overall performance of the engine based on the experimental data, we had concluded that the specific fuel consumption was improved about 8-10%, and the exhaust emission performance was improved correspondingly after electronic control, the improved ratio was about 10% for HC emission and 97% for CO emission. Copyright © 2001 ATA, SAE International and SAE of Japan.

The distribution of luminous intensity of radicals, CH and C_2 were measured under atmospheric pressure and high combustion pressure. From the experiment with the premixed laminar burner, it could be confirmed that the radical luminescence distribution and the distribution of radical luminous intensity ratio could be measured. And it was found that the luminous intensity of CH radical was greater than that of C_2 radical and the value of luminous intensity ratio became small as the mixture became rich. From the experiment with the combustion chamber, it was also found that the luminous intensity became strong as the combustion pressure rose and the value of luminous intensity ratio became large as the combustion pressure rose.

The purpose of this study is to establish a method to improve the accuracy of acquiring pressure trace of an internal combustion engine. Inaccuracy in acquiring pressure trace is caused by the thermal deformation of the diaphragm of a pressure transducer and the electric circuit characteristic of a charge amplifier. A correcting equation for inaccuracy caused by the thermal deformation was acquired by analyzing the deformation model of the diaphragm of the pressure transducer used in the experiment with a burner. As for the imaccuracy caused by the electric circuit characteristic of the charge amplifier, correcting equation was acquired by analyzing the simplified electric circuit of charge amplifier. By applying these equations, a method of improving the accuracy of pressure trace for four types of water-cooled pressure transducer was established.

This investigation was concerned with the rate of heat transfer from the working gases to the combustion chamber walls of the internal combustion engines. The numerical formula for estimating the heat transfer to the combustion chamber wall was derived from the theoretical analysis and the experiment, which were used the constant volume combustion chamber and the actual gasoline engine. As a result, mean heat transfer in the internal combustion engine becomes possible to estimate with measuring the cylinder pressure. In addition, the derived numerical formula forms with quite simple variables. Therefore it is very useful for engine design. Copyright © 2000 Society of Automotive Engineers, Inc.

The thire paper examined the effect of turbulence by combustion causes to heat loss. But in real gasoline engine, the air fuel mixture, which inhaled it in cylinder includes initial turbulence. Therefore effect of initial turbulence of mixture was examined to estimate heat loss of gasoline engine in this paper. The initial turbulence was expressed using a simple model in which the momentum of turbulence damps when turbulence moves from unburned gas to burned gas. The expression to estimate heat loss is expressed as next by using the model. [numerical formula] Where the third term expressed the effect of initial turbulence and the coefficient: Cd&ap;0.24 has expressed damping of initial turbulence.