201 ビデオ画像輝度値減衰法による室内通風模型の換気回数測定精度に及ぼす実験条件の影響について

抄録

Air change rates in a cross-ventilation model were measured from decay curves of video image signals by the step down method under the perfect mixing assumption. From the wind tunnel experiments, the following results were drawn. 1) The proposed calibration method could measure the air change rates with a precision accuracy of more than 73 % even for the low dynamic ranges of cameras to adjust black balances of images. 2) For oil mists as tracer, the laser power of more than 0.5 watt was enough to visualize the mist movements in the model for the air change rates. 3) The air change rates, obtained by the video image method was proportional to the reference velocities. 4) The maximum image signals in the case for the smoke liquid mists was lower than those for the oil mists due to the smaller particle diameters. 5) The results of air change rates measured by video image method could have good agreements with those derived from decay curves by the tracer gas method using a high-speed hydrocarbon analyzer