Hironobu Yamakawa

Development of High Efficiency and Low Noise Cross-Flow Fans for Room Air Conditioner Indoor Unit

Cross flow fans are used for fan systems in a household room air conditioner indoor unit. In recently, in the view of environmental problem and cost saving, energy saving performance is important specification for users. Reducing fan motor electric power consumption is effective for this purpose. And also low noise fans are needed for comfortable circumferences. To meet these user needs, we developed a high efficiency and silent cross flow fan using CFD (Computational Fluid Dynamics) and experiments. In CFD, numerical model is calculated by commercial software using steady state, Reynolds-averaged Navier-Stokes (RANS) and k-e turbulent flow model. The developed cross flow fan is geometrically characterized by the solidity (the ratio of the blade pitch and blade cord length) distribution, and the blade edge shape. The solidity average of developed fan was larger than the conventional fan and the solidity distribution was smooth. And the developed fan has the sinusoidal shape of the outer diameter edge. This sinusoidal shape edge makes pressure distribution on the tongue to be more dispersed compare to that of conventional straight edge so that tonal noise was restrained.Copyright

Development of High Efficiency Propeller Fan for Heat-Pump Unit Using CFD and Numerical Optimization

We developed a high-efficiency propeller fan to reduce electric power consumption of the fan motor for outdoor heatpump units, and we developed a designing tool combining computational fluid dynamics (CFD) with multi-objective optimization techniques based on the genetic algorithm (GA). In CFD, a numerical model is calculated using commercial software based on steady state, Reynolds-averaged Navier-Stokes (RANS) and k-e turbulent flow model. The objective functions are fan efficiency and fan noise for optimization. Fan efficiency is calculated directly from the CFD results, and fan noise is calculated using an aerodynamic noise prediction model using the relative inlet and outlet velocities of the fan blades from the CFD results. We fabricated a high-efficiency propeller fan characterized with curled trailing edge tips from Pareto optimal solutions. The experimental results from the performance of the fan showed the developed fan was more efficient than conventional fan.© 2011 ASME

A Multi-Layered Capillary Chip for High-Throughput Analysis

We fabricated a multi-layered chip consisting of four capillary chips that are optically optimised and excited with one beam. Sample fluorescent light from each capillary was detected cleanly, so the multi-layered chip is suitable for high-throughput analysis of plural samples.