The Simulation of Wind Turbine for Truck Application

• Main Authors: Kuang-YaoChang, 張光耀
• Other Authors: Shih-Hsiung Chen
• Format: Others
• Language: zh-TW
• Published: 2014
• Online Access: http://ndltd.ncl.edu.tw/handle/87790705747264985295

碩士 === 國立成功大學 === 航空太空工程學系 === 102 === SUMMARY Conventional air-conditioning system of the heavy-duty truck is driven by belt or gear, thus increasing the extra engine power output and fuel consumption. In this study, the wind turbine installed in the air deflector, use the wind energy of traveling truck to supply air-conditioning system, no longer be driven by a belt, and expects it can save additional fuel consumption caused by a belt driven. This study using CFD with SST turbulence model to simulate different situations when heavy-duty truck traveling at 100 km/h speed, which the flow field and drag of heavy-duty truck with and without air deflector, wind turbine installed in the air deflector with 45 degree (Case A), and remove the plate at case A wind turbine outlet top (Case B), then compare the wind turbine power of case A and B, finally we discuss the economic benefits of installed wind turbine. The results show that air deflector can reduce the drag coefficient of 6.1%, and the maximum power of both case A and B are more than 2000W. Although compared to the truck with air deflector, the drag coefficient of case A and B were increased by 5.05% and 9%, but compared with savings of engine power, case A and B can save 4.07% and 2.54% of the total engine output power respectively. Key words: CFD, Wind Turbine, Heavy-Duty Truck, Energy Saving INTRODUCTION The driver will be turned on the air conditioning for comfortable environment during driving, but the air conditioning compressor was driven by belt, it will add additional load to the engine then increase fuel consumption. In U.S.A., the fuel consumption of vehicle air conditioning is 26.4 billion liters for a year, equivalent to 5.5% of the total national fuel use, for the global environment and energy cause considerable harm. When heavy-duty trucks under the 65 mile/h (104.6 km/h) traveling speed, the air conditioning accounted for 4.5% of total engine output power, about 7.5kW. Air conditioning only allows the driver to drive the vehicle in a comfortable environment, but it consumes so much energy, if we can replace the current belt-driven system then will save a lot of energy. When heavy-duty truck traveling at high speed, the relative wind implied energy is considerably more, if able to use this energy to provide to air conditioning system then we can replace the current belt-driven system and save considerable energy. But how to choose wind turbine, how much electricity, whether to increase the drag and thus increase fuel consumption, engine power or the size of the savings are worth and so will be the focus of this study. MATERIALS AND METHODS This study using CFD methods to simulate the flow field of truck and wind turbine, and assuming the flow field is steady three-dimensional incompressible viscous flow, using finite volume method to solve three dimensional Reynolds average Navier-Stokes equations, and with the finite element method to calculate the flow field variables. Turbulence model used by Shear Stress Transport (SST), the model combines the advantage of both model and model and have high accuracy in predicting the flow separation. Wall function using Automatic Near-wall Treatment, this model is based on the boundary layer mesh when in viscous sub-layer using low Reynolds number formulation, in log-low region using wall function. RESULTS AND DISCUSSION In case of truck without air deflector, the airflow impacts the cabin ahead and the front of container, a high pressure zone generated here, and the container rear and the gap between cabin and container are behind bluff body so here generated low pressure zone, the pressure difference between high pressure and low pressure zone becomes aerodynamic drag. When the truck with air deflector, airflow moving along the air deflector, no longer impact to the front of container thus the high pressure zone at front of container is disappeared, reduce pressure difference between truck ahead and rear, also reduce the aerodynamic drag, about 6.1%. Compared to truck with air deflector, the container ahead high pressure zone appears again in case A, it caused by the wind turbine exit airflow impact the container. Because there are a plate at wind turbine outlet top, it will hinder the exit airflow moving along installation degree, making most of exit airflow impact container. Compare to the truck with air deflector, case A increase the drag coefficient about 5.05%. In the case B, the high pressure zone at container ahead also exist but smaller than case A, because after remove the plate at wind turbine outlet top, the exit airflow moving along wind turbine installation degree is more than case A so that the high pressure zone reduced. In addition, remove the plate will increase the pressure difference between air deflector ahead and rear, because the plate can obstruct the low pressure zone diffuse to air deflector rear, which caused by air deflector shape accelerated airflow. Compare to the truck with air deflector, case B increase the drag coefficient about 9%. The wind turbine maximum power of case B is more than case A about 17.9%, it caused by removing the plate. Although both case A and B increase the drag coefficient, but when we considering the power saving with replacing belt-driven system, the case A can reduce total engine output power about 4.07% and case B can reduce total engine output power about 2.54%. CONCLUSION This study using CFD method to simulate the heavy-duty truck with and without air deflector, and installed wind turbine in air deflector, when traveling at 100 km/h speed, and discuss the economic benefits of installed wind turbine. The results show that the air deflector have significant drag reduction effect, although the wind turbine will increase drag, when considering the power saving with replacing the current belt-driven system, can save considerable energy, the economic benefits are here.