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The Validation of the Pneumatic Actuators Numerical Approach

Source:http://www.flowxgroup.comUpdate Time:2014-10-24Hits:

Conventional valve benefits can be seen at the outer surfaces of the pneumatic actuators in terms of the inflow and outflow conditions. That is why conventional valves are widely used in the pneumatic actuators and on the sphere of the pipe surfaces in either boundary condition. The validation of the numerical approach concerning the pneumatic actuators can be performed through a comparison of the drag coefficients against empirical results for the flow past the pneumatic actuators sphere in the periodic vortex regime. On the other hand, this is because the periodical nature of the pneumatic actuators flow over the ball is considered to be due to periodical shedding of vortexes. To observe the pneumatic actuators vortexes shedding we need without any doubt to present the tours of plane velocity magnitude as well as the streamlines in the XY-plane in at least four times per one shedding period.

The development of pneumatic actuators vortexes and the conventional valve benefits is apparent in the field, where a large number of smaller scale pneumatic actuators eddies are expected to be merged into the stream wake. A lot of research has showed that the pneumatic actuators wake is rather narrow immediately behind the ball due to the delayed flow separation in the boundary layer. The pneumatic actuators wake width tends to increase as the distance from the separation point go further in the aspect of downstream. In fact, according to scientific research results, at the first stages the pneumatic actuators wake is in general sloped down relative to the axis of symmetry. At later stages, it will be sloped up and further evolution of the pneumatic actuators wake is characterized by up and down shifting behind the different valves of the pneumatic actuators. This regular motion of the pneumatic actuators wake can be better understood by the stream wise axis that is associated with inducing periodical force. This kind of force exists primarily in the pneumatic actuators span wise direction where the asymmetry is largest in the plane. The force is huge corresponding to the maximum lift force even though more comprehension about the pneumatic actuators shedding mechanism remains to be explored. This is especially true in the near electric actuators ball region, which can be provided by examination as well as the distribution of the streamlines over the pneumatic actuators ball. The pneumatic actuators boundary layer takes place before that of separation remains laminar and transition at separation point that will finally develop into a number of vortexes. These pneumatic actuators vortexes are periodically separating and are expanding in the aspect of downstream within the sphere with an effect that leads or point out to a mean lift force within the device.

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