申論題

4. A fan sends static air into a 45 m long； rectangular pipe of 200 mm x 300 mm. The air entering the pipe is 15℃and 750 mmHg absolute pressure, and the flow rate is 0.6 m³/s. What is the theoretical power required? For a smooth tube, f= 16/Re in laminar flow； f= in turbulent flow； Re is the Reynolds number. (20%)