Question

5. The closed-circuit wind tunnel flows air with a velocity of 200 ft/s [between sections (5) and (6)] at standard condition. The picture and diagram of the wind tunnels are provided below. The flow is driven by a fan that essentially increases the static pressure by the amount pı - p9 that is needed to overcome the head losses experienced by the fluid as it flows around the circuit. Determine the pressure rise (pi - ps). Conditions) Assume air is incompressible (Mach number is less than 0.3); Each corner has guide vanes with a loss coefficient of Kcorner = 0.2; Enlarging sections from the end of the test section (6) to the beginning of the nozzle (4) as a conical diffuser with KLdiffuser = 0.6; The loss coefficient for the conical nozzle between sections (4) and (5) and the flow straightening screens are KLnozzle = 0.2 and Kscreen = 4.0, respectively. V5= 200 ft/s (4) (5) (6) (7) Test section (3) Flow-straightening screens (8) Q (1) (9) Fan Area (ft) Velocity (ft/s) Location 22.0 36.4 1 Hint) 1. hi K (V2/2g) 28.6 28.0 2. When there is area change in the flow: 35.0 22.9 35.0 22.9 For conical diffuser (6 to 4), the velocity in the minor loss 4.0 200.0 formulation is the velocity at the inlet (section 6) 4.0 200.0 For conical nozzle (4 to 5), the velocity in the formulation 10.0 80.0 is the velocity at the exit (section 5) 8 18.0 44.4 22.0 36.4 23

Answer 1

Since air is assumed to be incompressible the density is taken to be 1.225 kg/m³=0.0765 lb/ft³.

g=9.81 m/s²=32.2 ft/s².

And (P-P Wa have (P-P) (P.-Pa)(Pa -Ps) +a-P.) +(P-Pr) (Ps -Pe) + (Pe -Pr) +(Pe-P) + Pr-Pe)+ tead lou A lio we ge4 P,-P, E Khis-2 Bh6-7 h7-5 + hi-3 h3-4 + h4- hir6+ + x v 0-6x 36.4 2 x 32.2 -/2.34 ft 23 he 2-3 KL Coner y Va Ki Jith V 29 29 0.2 x 0-62 6-6 28-6 10-16 29 x t 71 25 1-63 e.2 22-9 4-4 t+ Comu 29 KLsereen V4 kinozle V 29 22-2 I54. 79 fl- 4 x O-2 y 200 23 1-5 74 312 67 f 0-6x 2002 Ve KLiFfe het-7 29 keidtu + 29 +0-6r 80 79-So f o-2 x fo 23 hs-y 1kLoith 2L cornu Vi + 24 4 ft 44-42 29 + 0-6 x 44-4 o.2 x 57. 57 ft h1-7

h- fo Rb/te 0.0763 ft/ y32. 2 50-20 b/ft P,-P PA 24 01 61