PMMA粒子の熱泳動速度に気体種が及ぼす影響

国立大学法人長岡技術科学大

Rapeseed oil spray development of diesel idi spray nozzle under air movement influence

Rapeseed oil (RO) spray has very slow atomization due to its high viscosity nature. Although high injection pressure, high ambient temperature and combination of nozzle can promote faster atomization of rapeseed oil spray, another factor that was not discussed is the effect air movement that could positively influence RO spray development. To study the effect of air movement, in particular to generate the swirl (air movement inside the chamber), a swirler was used. Images were captured using a nano-spark shadowgraph photography technique and also high speed video imaging. Macrostructures of diesel sprays such as spray tip penetration length, spray shape, spraycone angle were obtained. Microstructures, such as droplet distribution and size were also studied. Result shows that IDI nozzle rapeseed oil spray has a narrow spray cone angle. The average droplet size is around 20~25µm. The large size of rapeseed oil droplet require assistant to improve atomization and results shows rapid air movement in chamber successfully improve atomizatio

Measurement of thermophoretic parameters for binary gas mixtures

The thermophoretic velocity of a particle in a gas mixture is measured by means of a microgravity experiment. Adopted particles are PMMA spheres of 2.91 mm in mean diameter, and gas mixtures chosen are argon–nitrogen, argon–carbon dioxide, and nitrogen–carbon dioxide. The temperature gradient and the pressure are 60 K/mm and 70 kPa, respectively. Terminal velocities of particles suspended in a gas are individually measured. The tangential momentum accommodation coefficient is estimated from experimental result by assuming the thermal accommodation coefficient at unity, and it is compared with predictions calculated from values of composing pure gases by means of some methods given in references; among those methods, the intermolecular-interaction�based method is found to be the best for all mixture conditions

Study on Mist Nozzle Spray Characteristics for Cooling Application

Evaporative cooling mist spray is a cost effective solution for many cooling applications. Selection of misting spray nozzle play a major role in order to provide the suitable spraying condition in regards to the application. One of the most widely use mist spray application is evaporative cooling of outdoor open area. This study was carried out to characterized the spray formation, size of droplet, velocity of the droplet and the angle of the spray formation from a commercial mist spray nozzle namely 1/8 SF-CE SM nozzle with 1 mm and 2 mm diameter hole. Water was supplied with different pressure of 1, 2 and 4 bar. High speed video camera and still digital camera using short burst of flash were used to produce the video and image for analysis. The results show that increase in water pressure affect the spray angle, increase droplet speed and decrease droplet size of the mist spray

Numerical study of variable length exhaust pipe in small engine

Small engines, with capacity not exceeding 150 cc, can be divided into two types: two-stroke and four-stroke engines. The exhaust pipe has significant influences on the performance of the engine. Thus, it is necessary to study factors that affect the exhaust in order to improve the performance of the engine. For this early stage, it would be appropriate to conduct the research by using simulations since they only require minimal resources and can be conducted in a short period. The objective of this study is to conduct the simulation for determining the required velocity and pressure in the exhaust pipe. The comparison is done between parameter values from different configuration of exhaust pipes; the most appropriate configuration is then proposed. Three types of exhaust pipe is proposed using computer software and simulations are carried out using ANSYS Workbench 15.0. Results show that the velocity and pressure fluctuate according to the diameter and length of the exhaust pipe. Model 3 exhaust pipe configurations have been selected as the most suitable exhaust pipe for obtaining the maximum pressure and velocity

Numerical simulation of aerofoil with flow injection at the upper surface

Separation of the boundary layer over an airfoil causes a significant increase in the adverse pressure gradients and the losses of energy resulting in the reduction of the lift force and the increment of drag force. Therefore, delaying and eliminating flow separation is necessary to improve its aerodynamic characteristics. In this study, an injection of flow was introduced at the upper surface/suction side of the aerofoil to control the boundary layer separation effectively. Flow around the NACA0012 airfoil was examined, with the position of flow injection jet at 90° relative to the tangential surface of the airfoil at 20%, 50% and 80% of its chord length. The flow injection velocity was varied from 0%, 10%, 30% and 50% of the free stream velocity, which corresponds to 0, 2.5 x 10-4, 2.25 x 10-3 and 6.25 x 10-3 of the momentum coefficient. The results showed that the most suitable condition was at 10% of the blowing amplitude (2.5 x 10-4 of the momentum coefficient) of flow injection at the trailing edge, which was around 80% of the chord length at the upper surface/suction side. This configuration can successfully increase the lift force and decrease the drag force of the aerofoil at the angle equal to or larger than a stall angle of 16° compared to the baseline aerofoil

Influence of Material Composition on Flame Spread Behaviour over Combustible Solid of Paper/Bagasse

Fire Safety Engineering is an application of science to improve the safety from the destructive effect of the fire. Paper is one of sources creating fire, however, research on flame spread towards paper is still not enough to describe about the phenomenon. Inspiration from this, the behavior of downward flame spread over paper/bagasse is experimentally investigated. Composition of 0%, 30%, 50%, 70% and 100% bagasse is determined for this research. Flame spread behavior for each composition is analyzed from the observation. Results show for each composition, the flame spreads with “U†shape at the beginning of combustion until the whole specimen. The result also shows that the flame spread rate decreases as bagasse composition increases. The highest flame spread is 0.8133 mm/s for pure paper and the lowest one is 0.4814 mm/s for pure bagasse. It infers that the flame spread shape and rate is influenced by the bagasse composition and density, respectively.Â

Analysis of Air Flow, Air and Fuel Induction for Internal Combustion Engine

In an internal combustion engine, performance, efficiency and emission formation depends on the formation of air-fuel mixture inside the engine cylinder. The fluid flow dynamics plays an important role for air-fuel mixture preparation to obtain the better engine combustion, performance and efficiency. This review article discuss the rotating flow (swirl and tumble) in premixed spark-ignition engine and its effect on turbulence generation and flame propagation. Rotating flow can substantially increase turbulence intensity for the duration of the combustion period. This review paper discusses the in-cylinder swirl and tumble flow that affects air induction during the combustion process in internal combustion engine. Alternatively, this study using computer simulation (Computational Fluid Dynamic, CFD) which offer the opportunity to carry out repetitive parameter studies. An integration-type flowmeter (IFM) also has been used which consists of ultrasonic flowmeter, that integrates the flowrate during the intake process, gives accurate measurements regardless of sampling time and frequency. Research parameter in this study was swirl and tumble that represents the fluid flow behavior occurred inside combustion chamber. Fuel injection and air mass also were the important parameters that have been discussed about in air induction process.  The results obtain from the numerical analysis can be employed to examine the homogeneity of air-fuel mixture structure for better combustion process and engine performance

Investigation The Influences of Electric Motor and Electric Go Kart Performance

This researcher focused at every type of electric motor and every force applied to a go kart. The goal of this research is to choose a prototype of an electric motor drive mechanism and test its performance on an electric go-kart. Furthermore, the purpose of this study is to establish the power requirements of an Electric Go-Kart, as well as its specific motion capabilities and performance specifications factors, in order to access the performance of the Electric Go-Kart motion. The benefit of developed electric go kart is to help decrease the pollution emitted and as a substitute to the typical combustion engine vehicle. However, due to its high congestion and pollution issue, a pollution with free vehicle created. In the first phase of the project, the researcher surveyed information related to the typical of electric motor that use in electric go kart. The second phase of the project is mainly on calculating the forces acted on the Electric Go Kart itself. Three main factor of movement behavior on go kart determined rolling resistance 54.88N, air resistance 28.4N and force gravity going uphill 552.98N. After that, the researcher selects drive system components with required specifications. The Brushless DC Motor was selected with 2000W 48V whose maximum output torque is 27.6Nm. Towards the end phase of the project, the electric go kart prototype was developed with actual size of go kart 1.94m length, 1.4m width and 0.5m height. Electric motor was analyzed on the motor speed, torque and power to make sure that the performance was approximately the set specifications. In conclusion, the project was success and it can produce a good performance at the go kart

Influence of material composition on flame spread behavior over combustible solid of paper/bagasse

Fire Safety Engineering is an application of science to improve the safety from the destructive effect of the fire. Paper is one of sources that easily catch fire, however, research on flame spread towards paper is still not enough to describe about the phenomenon. Inspiration from this, the behavior of downward flame spread over paper/bagasse is experimentally investigated. Composition of 0%, 30%, 50%, 70% and 100% bagasse is chosen for this research. Flame spread behavior for each composition is analyzed from the observation. Results show for each composition, the flame spreads with “U” shape at the beginning of combustion until the whole specimen. The result shows that the flame spread rate decreases as bagasse composition increases. The highest flame spread is 0.813 mm/s for pure paper and the lowest one is 0.481 mm/s for pure bagasse. Not only that, it also shows the flame spread rate decreases as the density increases. It is clarified that density for bagasse is higher than paper. Result infers that the flame spread shape and rate are not only influenced by the bagasse composition but also by the densit