Windage

The shortcomings of microhardness tests include numerous sources of errors not found in macrohardness tests such as friction, vibration, inertia, windage, and the skiH of the test operator. 

Power for each Hquid and the soHd phase must be added to get Pp. P, the soHds process power, = T -AN for scroU decanters, where = conveyor torque and AN = differential speed between bowl and conveyor. Pp is the friction power, ie, loss in bearings, seals, gears, belts, and fluid couplings. P, the windage power, = K and fi = viscosity of surrounding gas p = density of gas D = rotor outside diameter N = rpm and K = shape... 

Eddy current and hysteresis losses are complex quantities and can be estimated in a laboratory, on no load, in the form of power input, le.ss and friction and windage losses etc. as shown in Section 11.5. Based... 

Windage losses A result of friction between the moving parts of the motor and the movement of air, caused by the cooling fan, rotation of the rotor, etc. 

Core friction and windage loss (obtained from the no-load test)... 

Subtract the no-load stator copper loss from the stator input power at no-load, i.e. (P ( - i R ). This is the net no-load loss made up of core, friction, windage and stray losses. 

Interception with the zero voltage axis, which represents friction and windage losses, may be found by plotting a second graph with the square of the voltage as the abscissa and the watts as the ordinate (Figure 11.6). 

The no-load test is a very informative method to determine the no-load current, core and pulsation losses, friction and windage losses, magnetizing current and the no-load power factor. The test also reveals mechanical imbalance, if any, performance of the bearings, vibration and noise level of the motor. 

The watts input is the sum of the friction and windage losses, core loss and no-load primary loss (/njR )- The sum of friction, windage and core losses is obtained by... 

All turbomaehinery models eonsider rotor inertia, bearing losses, and windage. The intereonneeted piping is modeled as a pressure drop and a volume. 

For Main Air Blower serviee without a steam turbine in the string, the unit shall be started by first applying windage steam and then aeeelerating the train to rated speed using the eleetrie motor. After aehieving stable rated speed, the expander inlet valve will be... 

The 4 hr hot test shall be at the normal point exhaust temperature or 1,000°F, whichever is higher. Tlie temperature may be attained by recirculating the air heated by windage in a closed loop the temperature shall be controlled within 25°F of the desired value by adding steam to the loop. During the hot test, the vibration shall be monitored for conformance to the specified limits. 

Figure 6-7. Windage loss versus speed for pressurized and unpressurized magnetic bearing environments.

These equations convey the fact that windage loss is not only a function of rotating speed, but is also directly proportional to the density of the seal or purge gas filling the bearing housing. 

The required suction pressure to the expander is not available until the oxidizer tower reaches design pressure. With two compressors in operation this takes approximately 15 min. Since the expander wheel is mounted on the compressor pinion, enough flow must be available at startup to prevent overheating. The calculated windage loss of the expander wheel (40 hp) requires about 16,000 Ib/lir of flow to prevent overheating. 

The windbaek seal elosely resembles the labyrinth but has an entirely different operational prineiple. A serew-thread deviee winds the oil, whieh is earried around the bore by the windage of the shaft, into an internal drain for return to the system as shown in Figure l3-23a. 

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