Stall

As the angle of attack (a) is increased, the flow velocity on the upper side of the airfoil is increased, and that on the lower side is decreased. Since the Bernoulli equation [Eq. (5.15)] applies outside the boundary layer, this gives rise to a low pressure above the wing where the velocity is high, and a 

Since the variation in pressure across the boundary layer is slight, the pressure along the outer surface of the boundary layer AB in Fig. 6.1) closely approximates that on the airfoil CD in Fig. 6.1). Hence, potential flow theory, that assumes zero viscosity, gives a good approximation for lift. 

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We inb oduce a closed-path T defined by a parameter X. At the stalling point So, A, = 0 and when the path complete a full cycle, X — p(2tt, in case of circle). 

Using GAUSSIAN for Windows, we can carry out a MNDO, AMI. or PM3 optimization, of. for example, the IIP molecule, stalling from any reasonable II-F bond distance. The input file is similar to the standard MOPAC input file... 

Vacuum filtering can be a bit tricky, as the filter paper clogs up very quickly and stalls the process. With this stuff it is particularly important to get rid of as much of the solids as possible or your distillation be will very messy. A way round that I have found (that isn t in any book) was to use loads of filter papers, throw them all into a big beaker and then rinse them with solvent, then filter the solvent. Filter tiny amounts at a time, as soon as the paper blocks - stop and change the paper. I normally run the filtrate through at least twice. Any way you can make sure that you have done two... 

Other uses of ABS include consumer and industrial appHcations such as luggage, toys, medical devices, furniture, shower stalls, and bathroom fixtures. 

In Germany in the early 1950s, a 50 50 mixture of methanol and 2-propanol was blended with gasoline, first at a level of 7.5% and later at 1.5% (79). Complaints about stalling, power loss, and phase separation caused the ratio to be changed to 60 40 methanol 2-propanol but this apparentiy aggravated... 

J. R. Stall and co-workeis, Thetdonwoven Fabrics Handbook INDA, Cary, N.C., 1992. 

For spas, shower stalls, bath tubs, etc, a gel coat containing no fiber reinforcement is appHed first to the mold. It forms a smooth, strong, impervious, durable chemical, weather, and wear-resistant surface. The bulk of the resin, which may be reinforced with glass fiber, is appHed by hand lay-up or by spray gun. The article is then cured at or near ambient conditions. 

The resins have wide appHcation. In nonreinforced form they serve as insulating coatings for electrical coils (46—47). As fiber reinforced resins, they can be made by reaction injection mol ding into laminates, castings, and coatings (48—49). Fiber-reinforced resins are used in marine appHcations (recreational boats) automotive parts (50) bathroom countertops and shower stalls and tubs and more recendy as baUistic protection for military vehicles and aircraft. 

High in stalled co.sts. The incremental piping required for the steam supply system and the condensate return system must be installed, insulated, and, in the case of the supply system, additional steam traps are often required. The tracer itself is not expensive, but the labor required for installation is relatively high. Studies have shown that steam tracing svstems typically cost from 50 to 150 percent more than a comparable electric tracing system. 

Lower in stalled and operating co.st.s. Most studies have shown that electric tracing is less expensive to install and less expensive to operate. This is true for most apphcations. However, for some applications, the installed costs of steam tracing are equal to or less than electric tracing. 

When making a selection, the stall-out condition, which develops when the fan cannot produce any more air regardless of power input, should be considerecL... 

When the motor overheats, the thermostat opens, interrupting motorline current. Pilot thermostats mounted on the windings of larger motors trip the motor starter rather than interrupt line current. This method gives good protection for sustained overloads, but because of the thermal time lag between the copper winding and the thermostat it may not provide adequate protec tion for stalled conditions or severe overloads. 

Atomic absorption spectrometry (AAS) stalled its cai eer 50 years ago. During this time fundamentals of the method have been mostly discovered thus transforming AAS to very powerful but relatively simple method of analytical chemistry. Nowadays it is one of the most widespread methods in analytical labs. 

Torque. lEC 60034-1 stipulates for a minimum inbuilt capacity of a machine (all ratings and voltages) to sustain an excessive torque of 60% for a minimum of 15 seconds, without stalling or an abrupt change in its speed. This stipulation is to meet the need for an excessive torque of a transitory nature due to the above parameters or for a momentary excessive load torque itself during operation. This stipulation, however, would not apply to motors designed and manufactured to specific requirements. 

To ensure that the motor does not stall or lock-up during pick-up under such a condition, it should have an adequately high pull-out torque (Tpo). 

Judicious electrical design will ensure a pull-out torque slip as close to the full-load slip as possible and minimize the additional slip losses in such a condition. See Figure 1.8. A motor with a pull-out torque as close to full load slip as possible would also be able to meet a momentarily enhanced load torque during a contingency without any injurious heat or a stalling condition. 

Heating phenomenon in a motor during a stalled condition 2/45... 

In such a condition, if the heat generated in the windings raises the temperature of the windings by 6 above the temperature, the motor was operating just before stalling. Then by a differential form of the heat equation ... 

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