2007 Fiscal Year Final Research Report Summary
Study on evaluation method for cross-ventilation environment taken account of steady ventilation flow rates and thermal comfort
| Project/Area Number |
18360278
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Architectural environment/equipment
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| Research Institution | Tokyo Polytechnic University |
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Principal Investigator |
OHBA Masaaki Tokyo Polytechnic University, Faculty of Engineering, Professor (90130947)
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| Co-Investigator(Kenkyū-buntansha) |
KURABUCHI Takashi Tokyo University of Scence, Faculty of Engineering, Professor (70178094)
IINO Akinari Nigata Institue of Technology, Faculty of Engineering, Professor (80272706)
GOTO Tomonobu Yamaguchi University, Graduate School of Engineering, Lecturer (20386907)
IINO Yukari Niigata Seoryo University, 看護福祉学部, Lecturer (40212477)
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| Project Period (FY) |
2006 – 2007
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| Keywords | Cross-ventilation / Thermal comfort / Skin temperature of human body / Local dynamic similarity model / Infrared animation / Thermal image analysis / Coupled model / Airflow charcteristics |
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| Research Abstract |
The field experiments, wind tunnel experiments and image analysis have been carried out. The findings of the study can be summarized as follows.
(1) The local dynamic similarity model can predict discharge coefficients, which vary with wind direction and opening position, if some requirements are met. Four types of wind tunnel experiments were carried out in this study to investigate how strictly these requirements have to be met when the model is applied to inflow openings. There are no substantial problems in applying the model when the direction or profile of the tangential flow is changed or when there is a wall near the opening.
(2) The local dynamic similarity model was coupled with a COMIS network model. The prediction accuracy of ventilation flow rates was verified for one-zone and two-zone building models. The coupled model achieved better predictions of discharge coefficients and ventilation flow rates than the conventional orifice flow model.
(3) The airflow characteristics out
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side and inside a cross-ventilated room were measured by ultrasonic anemometers in summer 2006. The major contributions to the energy spectra of cross-ventilation are revealed in the frequency range less than 0.1Hz and that the energy spectra of cross-ventilation contain some region of wave numbers with an exponential decay of k-5/3.
(4) When the air velocity was more than 0.5m/s, various air velocity changes and airflow fluctuations in time and space made subjects feel more comfortable under cross-ventilation than under airflows from the air-conditioning system.
(5) The influence of air velocity fluctuations on surface temperature fluctuations of thermal mannequin was visualized in the experimental room under cross ventilated cases and under air conditioned cases. An image processing method to transfer the infrared animations to power spectrum images was proposed in order to clarify the frequency of surface temperature fluctuations.
(6) The influence of building coverage ratio on ventilation performance was small rather on roofs than on walls. A roof window was found to be a very effective tool for increasing ventilation flow rates especially in densely populated area. Less
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