Displacement cavity

Valve-Less Rectification Pumps, Fig. 14 Published data on micropumps with electrically drivtai moving mechanical component acting (as a pistrai) on the fluid in the displacement cavity. There is a distinct dependence betwetm relative operating fiequtaicy (related to resonance) and Stokes number, which is the similarity parameter of periodic fluid motion... 

Valve-Less Rectification Pumps, Fig. 21 An example of a planar version single-action pump made by one-sided etching in a metal plate. It is driven by alternating air pressure acting on the liquid surface in the displacement cavity. Rectification by convergent-divergent Venturi diodes... 

Valve-Less Rectification Pumps, Figure 19 Later improvement of the principle from Fig. 18. Energetic loss associated with inflow into the displacement cavity is reduced by the inlet being shaped as a diffuser. The small angle p (compared with the full 80°in Rg. 14) is made possible by the change of the jet direction due to the Coanda effect attachment to the curved wall... 

Valve-Less Rectification Pumps, Figure 20 The principle of the traveling-wave pump, two-phase, three-stage rectifier based on the principle from Fig. 19. A substantial proportion of the pumped liquid does not enter the displacement cavities - instead, it is dragged along with the wave... 

Positive Pumps. Positive pumps employed by the food industry have a rotating cavity between two lobes, two gears that rotate in opposite directions, or a crescent or stationary cavity and a rotor. Rotary positive pumps operate at relatively low speed. Fluid enters the cavity by gravity flow or from a centrifugal pump. The positive pump also may use a reciprocating cavity, and may be a plunger or piston pump. These pumps are not truly positive with respect to displacement, but are used for metering product flow. 

Positive-displacement pumps may be of either the reciprocating or the rotary type. In all positive-displacement pumps, a cavity or cavities are alternately filled and emptied of the pumped fluid by the action of the pump. 

Single cavity caused by gaseous displacement in a plastic. 

The interpretation of these remarkable properties has excited considerable interest whilst there is still some uncertainty as to detail, it is now generally agreed that in dilute solution the alkali metals ionize to give a cation M+ and a quasi-free electron which is distributed over a cavity in the solvent of radius 300-340 pm formed by displacement of 2-3 NH3 molecules. This species has a broad absorption band extending into the infrared with a maximum at 1500nm and it is the short wavelength tail of this band which gives rise to the deep-blue colour of the solutions. The cavity model also interprets the fact that dissolution occurs with considerable expansion of volume so that the solutions have densities that are appreciably lower than that of liquid ammonia itself. The variation of properties with concentration can best be explained in terms of three equilibria between five solute species M, M2, M+, M and e ... 

The rotor of the Moineau-type positive displacement motor has a helical design. The axial wave number of the rotor is one less than the axial wave number for the stator for a given chamber. This allows the formation of a series of fluid cavities as the rotor rotates. The number of stator wave lengths n and the number of rotor wave lengths n per chamber are related by [79,86]... 

Downhole Mud Motor Optimization. Downhole mud motors in use today are practically all of the positive displacement type (sometimes called the moving cavity ). A description of these motors has been given in section 4.10. The theoretical characteristics curves of the motors are shown in Figure 4-315 in arbitrary units. 

The main source of spontaneous polarization in crystals is the relative freedom of cations that fit loosely into the crystal s octahedral cavities. The number of degrees of freedom of the octahedrons affects the spontaneous polarization value and hence influences the crystal s ferroelectric properties. Abrahams and Keve [389] classified ferroelectric materials into three structural categories according to their atomic displacement mechanisms onedimensional, two-dimensional and three-dimensional. 

We then consider a model problem of bouyancy recirculation in a closed cavity, using the same mesh of the previous example. Here the vertical boundaries are held at fixed temperatures, the left hotter than the right, while the horizontal boundaries are left unconstrained. A linear temperature gradient is thus set up between the left and right boundaries. The cooler and denser fluid at the right will tend to move down and displace the warm fluid at the left, setting up a clockwise circulation as seen in the streamline contour plot of Figure 6. 

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