Inertial devices

In addition to the deposition mechanisms themselves, methods for preliminary conditioning of aerosols may be used to increase the effectiveness of the deposition mechanisms subsequently apphed. One such conditioning method consists of imposing on the gas nigh-intensity acoustic vibrations to cause collisions and flocculation of the aerosol particles, producing large particles that can be separated by simple inertial devices such as cyclones. This process, termed sonic (or acoustic) agglomeration, has attained only hmited commercial acceptance. 

Inertial collectors for mists and droplets are widely used. They include cyclone collectors, baffle systems, and skimmers in ductwork. Inertial devices can be used as primary collection systems, precleaners for other... 

The simplest approach to sampling aerosols is to use filtration or an inertial device that traps all the airborne material. This would be useful for determining the total amount... 

Some other devices that can be used when the main obnoxious material is large particles are gravity settlers, cyclones, and inertial devices. Gravity settlers rely on gravity to allow the particles to fall into collecting plates. These should not be used on particles smaller than 40/a.25 Cyclones (see Fig. 8-10) depend on centrifugal... 

Filtration is a suitable method for the collection of aerosols for microscopy, as mentioned previously. Particles may also be collected using inertial devices and may be examined by microscopy [73]. A third method that has not been mentioned is electrostatic precipitation, or sampling. 

Cyclone Samplers. A cyclone is an inertial device that is commonly used in industrial applications for removing particles from large air flows. A particle-laden air stream enters the cyclone body and forms an outer spiral moving downward towards the bottom of the cyclone. Larger particles are collected on the outer wall due to centrifugal force. Smaller particles follow the airstream that forms the inner spiral and leave the cyclone through the exit tube. Application of a water spray to the outer walls of a cyclone facilitates particle collection and preservation. (Boiarski etal., 1995). 

Cannot be used for up to 25 % turnup capacit) avoid the use of inertial devices for up to 25 % turndown capacity. 

The next major mechanism grouping is that involved in the attitude control of the spacecraft. To achieve 3-axis stabilisation, a combination of inertial and thruster control is used. Inertial devices are momentum wheels (fixed speed, typically up to 5000 rpm) or reaction wheels (variable speed, typically +3000 rpm), both are usually link to gyroscopes (typically speed 10,000 rpm, but used intermittently). Inertial devices are required to continuously operate up to 15 years (>10 revs) with near constant torque behaviour. Bearings, cage stability and lubrication are the key tribological issues. Thrust is also achieved by mono- or bipropellants controlled by valves. The sealing of... 

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