The type selecting of fan presses undermentioned measure to undertake commonly: 1, what computation needs ventilation inside affirmatory channel: 2, what computation needs At(N of × of P of △ of total thrust ItIt= ) among them, at: Channel cross section accumulates (M2) △ P: Each obstruction the sum (Pa) ; Answer commonly plan reach following 4: 1) obstruction of channel air inlet and give blast tuyere instruction; 2) obstruction of channel surface attrition, suspensory fan device, bracket reachs the guide resistance that cause; 3) traffic obstruction; 4) the pressure that differ because of temperature, baric, wind speed and is born is poor between channel imports and exports the obstruction that produces; 3, the range that the overall program that affirmatory fan arranges needs total thrust and efflux fan to offer thrust according to channel length, place, preliminary and affirmatory decorate M group fan in all on channel overall length, stage of every groups of N, the thrust of every typhoon machine is T. The total thrust of Tt of ≥ of T of × of N of contented M × asks, consider following limitation condition at the same time: 1) when N typhoon machine is paratactic, transverse span should be more than its center line diameter of 2 times fan. 2) M group (stage) when fan serial, fore-and-aft span should be more than diameter of 10 times channel. 4, the function of the affirmatory efflux fan of parameter of odd typhoon machine brings to bear on to be measured at the thrust of air current with its, the thrust that fan produces is reasonable by classy Yu Feng the momentum of air current of machine imports and exports is differred (what momentum is equal to air current mass flow and velocity of flow is good indigestion) , in fan test condition falls, the momentum that imports air current is 0, can calculate so go out to fall in test condition, the academic thrust of fan: : of ρ of Q2/A(N) of ρ of V= of × of Q of × of ρ of academic thrust = ? G/m3)Q of ╧ of caries of palm Du: Wind force (M3/s)A: ? ╩ of of Biao of to shirk of black Zhui 2) testing stand is worn 0 what measure thrust T1 to be academic thrust commonly. 85-1.
05 times. Depend on shed a structure that distributings to reach muffler with fan interior. The fan thrust data that gives out in chart of fan performance data all is worn with testing stand measure thrust to be accurate, but the usable thrust T that measures thrust to still not be equal to fan outfit to be able to arise inside channel, because fan hoisting can be carried on his shoulder or back by the meeting when channel is medium when channel is medium by the discharge of generation of speed of the air current in channel,this is of action influence (Kodak favour effect) , usable thrust decreases. Express and the degree of the influence can calculate with coefficient K1 and K2: K2 of × of T=T1 × K1 or T1=T (K1 × K2) among them T: Install the efflux fan in channel to be able to use thrust (N) T1: Testing stand wears measure thrust (N) K1: The to fan thrust influence of speed of average air current and fan exit wind speed in channel coefficient K2: Fan axis sheds the influence coefficient that leaves from the span of channel wall CNC Milling