Determine the absolute roughness of phenolic duct (RP-1764)

Figures & data

Table 1. Dimensions of ducts tested with 3.05 m (10 ft) and 1.52 m (5 ft) section lengths.

W × H, mm × mm (in. × in.)	Aspect ratio (W/H)	Dh, mm (in.)	Number of flanges in test section		Ratio of number of flanges in test section (short duct/long duct)
			Duct section length 3.05 m (10 ft)	Duct section length 1.52 m (5 ft)
305 × 152 (12 × 6)	2	203 (8)	1	2	2.0
305 × 305 (12 × 12)	1	305 (12)	3	5	1.7
610 × 305 (24 × 12)	2	406 (16)	3	7	2.3
559 × 279 (22 × 11)	2	373 (14.7)	4	7	1.8
559 × 559 (22 × 22)	1	559 (22)	5	10	2.0
1118 × 559 (44 × 22)	2	744 (29.3)	7	13	1.9
1118 × 279 (44 × 11)	4	447 (17.6)	4	8	2.0

Fig. 1. Test setup.

Fig. 2. Retaining screws factory installed by manufacturer mounted around the periphery of the flanges.

Fig. 3. Self-adhesive foam gasket applied to flange.

Fig. 4. Bolt connection at flange corner with caulk applied in addition to manufacturer’s instructions.

Fig. 5. Four-bolt flange assembly with cleat and tape.

Table 2. Uncertainties in measured parameters.

Test section temperature	0.6 °C (1.0 °F)
Dry-bulb temperature	0.6 °C (1.0 °F)
Wet-bulb temperature	0.6 °C (1.0 °F)
Barometric pressure	0.01 in. Hg (34 Pa)
Plenum chamber temperature	0.6 °C (1.0 °F)
Plenum chamber static pressure	0.1 in. wg (25 Pa)
Nozzle chamber pressure loss	0.01 in. wg (2.5 Pa)
Test section static pressure	0.01 in. wg (2.5 Pa)
Test section pressure loss	0.001 in. wg (0.25 Pa)
Duct height/width	in. (2.5 mm)
Test section length	0.50 in. (13 mm)

Fig. 6. Moody diagram for a 305 mm ×152 mm (12 in. × 6 in.) phenolic duct with 3.05 m (10 ft) sections connected by four-bolt flanges (no internal reinforcements installed).

Fig. 7. Moody diagram for a 305 mm ×305 mm (12 in. × 12 in.) phenolic duct with 3.05 m (10 ft) sections connected by four-bolt flanges (no internal reinforcements installed).

Fig. 8. Moody diagram for a 610 mm ×305 mm (24 in. × 12 in.) phenolic duct with 3.05 m (10 ft) sections connected by four-bolt flanges (no internal reinforcements installed).

Fig. 9. Moody diagram for a 559 mm ×279 mm (22 in. × 11 in.) phenolic duct with 3.05 m (10 ft) sections connected by four-bolt flanges (no internal reinforcements installed).

Fig. 10. Moody diagram for a 559 mm ×559 mm (22 in. × 22 in.) phenolic duct with 3.05 m (10 ft) sections connected by four-bolt flanges (no internal reinforcements installed).

Fig. 11. Moody diagram for a 1118 mm ×559 mm (44 in. × 22 in.) phenolic duct with 3.05 m (10 ft) sections connected by four-bolt flanges (no internal reinforcements installed).

Fig. 12. Moody diagram for a 1118 mm ×279 mm (44 in. × 11 in.) phenolic duct with 3.05 m (10 ft) sections connected by four-bolt flanges (no internal reinforcements installed).

Fig. 13. Moody diagram for a 305 mm ×152 mm (12 in. × 6 in.) phenolic duct with 1.52 m (5 ft) sections connected by four-bolt flanges (no internal reinforcements installed).

Fig. 14. Moody diagram for a 305 mm ×305 mm (12 in. × 12 in.) phenolic duct with 1.52 m (5 ft) sections connected by four-bolt flanges (no internal reinforcements installed).

Fig. 15. Moody diagram for a 610 mm ×305 mm (24 in. × 12 in.) phenolic duct with 1.52 m (5 ft) sections connected by four-bolt flanges (no internal reinforcements installed).

Fig. 16. Moody diagram for a 559 mm ×279 mm (22 in. × 11 in.) phenolic duct with 1.52 m (5 ft) sections connected by four-bolt flanges (no internal reinforcements installed).

Fig. 17. Moody diagram for a 559 mm ×559 mm (22 in. × 22 in.) phenolic duct with 1.52 m (5 ft) sections connected by four-bolt flanges (no internal reinforcements installed).

Fig. 18. Moody diagram for a 1118 mm ×559 mm (44 in. × 22 in.) phenolic duct with 1.52 m (5 ft) sections connected by four-bolt flanges (no internal reinforcements installed).

Fig. 19. Moody diagram for a 1118 mm ×279 mm (44 in. × 11 in.) phenolic duct with 1.52 m (5 ft) sections connected by four-bolt flanges (no internal reinforcements installed).

Table 3. Relative and absolute roughness values for phenolic ducts (no internal reinforcements installed).

W × H, mm × mm (in. × in.)	Aspect ratio (W/H)	Dh, mm (in.)	ε/Dh		ε, mm (ft)
			3.0 m (10 ft) Section lengths	1.5 m (5 ft) Section lengths	3.0 m (10 ft) Section lengths	1.5 m (5 ft) Section lengths
305 × 152 (12 × 6)	2	203 (8)	0.0005	0.0010	0.102 (0.00033)	0.203 (0.00067)
305 × 305 (12 × 12)	1	305 (12)	0.0003	0.0006	0.092 (0.00030)	0.183 (0.00060)
610 × 305 (24 × 12)	2	406 (16)	0.0002	0.0006	0.081 (0.00026)	0.244 (0.00080)
559 × 279 (22 × 11)	2	373 (14.7)	0.0002	0.0004	0.075 (0.00025)	0.149 (0.00049)
559 × 559 (22 × 22)	1	559 (22)	0.0003	0.0007	0.168 (0.00055)	0.391 (0.00128)
1118 × 559 (44 × 22)	2	744 (29.3)	0.0004	0.0004	0.298 (0.00098)	0.298 (0.00098)
1118 × 279 (44 × 11)	4	447 (17.6)	0.0003	0.0007	0.134 (0.00044)	0.313 (0.00103)
Average roughness values			0.0003	0.0006	0.136 (0.00044)	0.254 (0.00084)