Experimental Studies on the Pressure Drop Characteristics of Fiber Mats

By using beds of glass fiber with adiameter of 4-270μ as shown in Table 1, we investigated the various pressure drop characteristics and obtained the following results.(1) Pressure drops of the fiber mats decrease with the reduction of the area ratio Ai/A0, i.c. area ratio of masked face area to initial face area of the fiber mat. And the pressure drop Δpf changes with filter thickness L or fiber diameter Df (Figs. 5, 6, 7 & 8). (2) From the definition of a drag coefficient of a fiber mat, the experimental drag coefficient CD, were obtained, and Correlated with Reynolds number NRe. (Fig. 9) The results are represented by the empirical Eq. (5) or (6).In case 10-3 NRe 1.5×1010-3CDe=0.6+4.7/√NRe+11NRe Eq. (5)(3) In Fig. 9, the curved line shows the vaLues calculated from Eq. (5), which are in agreement with the experimental data. Comparison was made between these values and those obtained from other investigators' equations, and the Iberalls' equation was found to be in agreement with ours in case NRe 1. When NRe 1, however, all the values obtained from other investigators' equations deviated from the experimental data.(4) The pressure drops of the fiber mats were proportional to (1-e)m in our experiments (Eq. 7). When this relation is introduced in to Eq. (4), in the place of (1-e), we may call it a modifid drag coefficient CDm. The correlations of CDm vs. NRe can be given by Fig. 12 in the same way as by Fig. 9, and the experimental data fall exactly on the straight line when NRe 1(CDm∝NRe-1), and they show tendencies similar to frictional factors of acircular pipe for the turbulent region when NRe 1 (Eq. 8).