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POWER PLANT ACOUSTICS Episode 4

Tham khảo tài liệu 'power plant acoustics episode 4', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | TM 5 805 9 AFM 88-20 NAVFAC DM-3.14 Table 3-3. Approximate insertion loss in dB of 8-ft.-long 4-in.-thick parallel baffles separated by various with air spaces. Octave Frequency Band Hz 4 In. 50 Width of Air 8 In. 12 In. Percent Open 67 75 Space 16 In. Area 80 24 In. 86 63a 3 2 1 1 0 125 kJ 3 2 2 250 16 13 8 6 4 500 32 25 16 13 10 1000 56 38 19 16 12 2000 48 35 13 11 8 4ooo 40 26 10 8 6 8000 20 18 7 6 4 a. Insertion loss values usually are not measured and quoted for the I 31-Hz octave band. For calculations assume the 31-Hz insertion loss is about 6o of the 63-Hz insertion loss rounded off to the ỴẠ gi o d o 4 rlo Ti Tn l Table 3-4. Approximate insertion loss in dB of various lengths of 4-in.-thick parallel baffles separated by 8-in.-wide air spaces 67 open area . Octave Frequency Band Hz Length of Baffles 4 Ft. 8 Ft. 12 Ft. 16 Ft. 63a 1 2 . 3 4 125 3 5 7 9 250 8 13 18 22 500 16 25 34 43 1000 25 38 52 65 2000 22 35 47 58 4000 17 26 3 41 8000 13 18 23 27 a. Insertion loss values usually are not measured and quoted for the 31-Hz octave band. For calculations assume the 31-Hz insertion loss is about 6o of the 63-Hz insertion loss rounded off to the nearest decibel. 3-6 TM 5 805 9 AFM 88-20 NAVFAC DM-3.14 Table 3-5. Approximate insertion loss in dB of various lengths of 8-in.-thick parallel baffles separated by 12-in.-wide air spaces 60 open area . Octave Frequency Band Hz Length of Baffles 4 Ft. 8 Ft 12 Ft. 16 Ft. 63a 2 4 5 7 125 5 8 11 14 250 10 18 25 32 500 16 27 37 46 1000 15 23 31 38 2000 13 19 25 30 4000 10 14 19 24 8000 6 10 14 17 a. Insertion loss values usually are not measured and quoted for the 31-Hz octave band. For calculations assume the 31-Hz insertion loss is about 6o of the 63-Hz insertion loss rounded off to the nearest decibel. Table 3-6. Approximate insertion loss in dB of various lengths of 8-in.-thick parallel baffles separated by 8-in.-wide air spaces 50 pen area . Octave Frequency Band Hz Length of Baffles 4 Ft 8 Ft. 12 Ft. 16 Ft 63a 3 5 7 9 .