| Budget Amount *help |
¥3,500,000 (Direct Cost: ¥3,500,000)
Fiscal Year 2002: ¥900,000 (Direct Cost: ¥900,000)
Fiscal Year 2001: ¥2,600,000 (Direct Cost: ¥2,600,000)
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| Research Abstract |
A jet fan is a reversible axial flow fan fitted with upstream and downstream cylindrical silencers and has been used in a vehicle tunnel for longitudinal ventilation and safety measure to suppress the fire spreading in case of car accident. To secure more favorable vehicle tunnels, which should be planned based on minimizing the cost at construction and the energy consumption at operation, improvement of jet-fan performance is strongly expected. For switching flow direction promptly, a method to drive a rotor in the opposite direction is almost always adopted due to reliability. However, a rotor blade that gives high aerodynamic performance for both flow directions is still unclear, because it has been developed under the one-way flow.
The purposes of present research for two years are to investigate the performance of a rotor blade associated with its geometry by using the CFD, and to evaluate the performance of a jet fan with rotor developed based on the CFD experimentally. In the fir
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st year, we confirmed that thin trailing edge is the most desirable among many parameters for camber-less blade section. Then, we designed a two stage jet fan, considering those factors such as blade load, noise, etc. We also paid attention to the vortex type of rotor blade, and selected peripheral component of absolute velocity being constant in the radial direction together with the forced vortex type. We conducted performance test of a proposed jet fan of 630 dia. Since the stand-alone test is necessary for a jet fan, an array of eight 3-holePitot tubes mounted on rotatable support was used to measure the air flow at the exit plane associated with rotational speed and blade setting angle as major parameters. From the test, we can see better jet-fan performance was achieved. Regarding the fan noise, as a typical example, sound pressure level was less than 90 dB even at the exit side under the shorter silencer of around 10%. Distributions of velocity and pressure at each plane upstream and downstream of rotors were also measured, and the corresponding results shows that the proposed vortex type is proper for a 2 stage jet fan having high aerodynamic performance. Further, we confirmed that the turbulent flow analysis was reasonably usable to predict the flow through a jet fan. Less
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