Database on Indoor / Outdoor Air Pollution

1 OUTLINE OF WIND TUNNEL EXPERIMENTS

　　　　 The flow and concentration fields around a building within the isothermal boundary layer were selected for this database. Detailed measurements were reported by the present authors [1], as outlined below. The experiment was conducted in the wind tunnel (cross section at measurement part: 1.2 m × 1.0 m) of Tokyo Polytechnic University. The model building had a height (H) of 200 mm, a width (W) of 100 mm, and a depth (D) of 100 mm (H :W :D = 2:1:1) as shown in Fig. 1, and was located in a turbulent boundary layer with a power index of about 1/4(Fig.2). A point gas source was set on the floor 50 mm leeward of the model building. Tracer gas (C2H4: ethylene) was released from a hole (diameter: 2 mm) at a flow rate of q=5.83x10^-6 m3/s. The Reynolds number based on H (building height) and <uH> (inflow velocity at building height) was about 56,000. Measurement points were placed at four planes as shown in Fig. 3.The wind velocity and gas concentration were simultaneously measured using a split film probe for the wind velocity and a fast response flame ionization detector for the gas concentration. The sampling frequency was set at 1,000 Hz, to obtain 120,000 data in 120 seconds. In this wind tunnel experiment, the authors conducted uncertainty analysis [2],[3],[4] to check the reliability of the measurement data.

Figure 1 Flow Field Measured for This Database


(a) Mean Velocity	(b) Normal Stress(x/H=-2.5)

Figure 2 Inflow Profile without a Model Building

Figure 3 Measurement Point Locations

2 SYMBOLS

	x, y, z	: three components of space coordinates (stream wise, lateral, vertical)
	<ζ>	: time averaged variable ζ
	ζ’	: variation of variable ζ, ζ’= ζ－<ζ>
	σζ	: standard deviation of variable ζ
	H	: building height (0.2 m)
	u, v, w	: three components of the velocity vector (m/s)
	usc	: scalar velocity, usc= (<u>^2 + <v>^2 + <w>^2)^0.5 (m/s)
	<uH>	: <u> value at inflow of computational domain at height H (4.2 m/s)
	c	: gas concentration (ppm)
	q	: released gas emission amount (5.83x10^-6 m3/s)
	cgas	: released tracer gas concentration (1.0 x 10^6 ppm)
	c0	: reference gas concentration,c0 = cgas q/<uH>H^2 (ppm)

3 EXPERIMENTAL DATABASE

4 REFERENCE

　　　[1] H.Tanaka, R.Yoshie, Cheng-Hu Hu, Uncertainty in Measurements of Velocity and Concentration around a Building,
　　　　　 The 4th International Symposium on Computational Wind Engineering, pp.549-552, June, 2006. [pdf]
　　　[2] ISO, Guide to the Expression of Uncertainty in Measurement, 1993.
　　　[3] L. Kirkup and B. Frenkel: An introduction to uncertainty in measurement, Cambridge University press, 2006
　　　[4] The foundation of modern science and technology from the Physics Laboratory of NIST,
　　　　　 http://physics.nist.gov/cuu/Uncertainty/basic.html, (accessed 2005-10-22).

5 ACKNOWLEDGEMENT

　　　　The following students of Tokyo Polytechnic University assisted us in wind tunnel experiment for this database. We would like to express our heartfelt thanks to them.
　　　　　　・ Mr. Tsuyoshi KOBAYASHI
　　　　　　・ Mr. Tetsuji MIDORIKAWA
　　　　　　・ Mr. Taigo SUGIMOTO

6 CONTACT INFORMATION

　　　　Email: yoshie@arch.t-kougei.ac.jp (Prof. Yoshie)

Back

Copyright The 21st Century Center of Excellent Program
Wind Effects on Buildings and Urban Environment, Tokyo Polytechnic University