Windage losses

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)... 

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... 

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. 

To determine the required amount of planned blowdown, subtract windage losses from B. Use Table 1 for windage losses in liew of manufacturer s or other test data. 

For example, the windage loss associated with the rotating wheels increases drag. Covering the wheel wells can reduce this adverse effect. Although suitable for rear wheels, a body-mounted cover over the front wheel wells interferes vdth steering because during sharp turns, the front wheels extend beyond the plan-view profile of the car body. 

Aside from the efficiency of the motor itself, energy efficiency is very dependent upon proper sizing. While the efficiency of a motor is fairly constant from full load down to half load, when a motor operates at less than 40 percent of its full load, efficiency drops considerably, since magnetic, friction, and windage losses remain fairly constant regardless of the load. Moreover, the power factor drops continuously as... 

Drift Loss or Windage Loss the amount of water lost from a tower as fine droplets entrained in the leaving air. For an atmospheric type tower this is usually 0.1-0.2% of the total water circulated. For mechanical draft towers it is usually less. 

The rate of evaporation from a cooling tower is approximately 1 per cent of the circulation rate for each 5°C drop in temperature across the tower, or about 7 liters/h per ton of refrigeration. Windage losses will obviously depend on the prevailing wind conditions and the design of the tower with regard to spray elimination but, typically, these are about 0.2 per cent of the circulation rate. 

Type of Cooling Device Windage Loss as Percentage of System... 

Windage losses or drift vary with the type of tower and local conditions. Average estimates for normal tower operations are 0.3-1% of circulation for natural-draft towers and 0.1-0.3% of circulation for mechanical-draft towers. 

It must be noted that concentration of soluble salts in blowdown and windage losses equals that in circulating water. Thus, Xm = ppm of any soluble salts in M and... 

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