Section 3 Hydraulics

In contrast to the diffusion approach, in the previous sections hydraulic permeation was considered as the effective mode of water transport. Transformed to the form of an effective diffusion coefficient the transport coefficient of the latter model becomes... 

Wells may be drilled at a constant angle to the target or dropped off to a lower angle through the reservoir section. To build, maintain or drop the deviation angle stabilisers are run in the bottom hole assembly (Fig. 3.15). A change in deviation used to require a round trip to change the position of those stabilisers in the bottom hole assembly. In recent years, adjustable, hydraulically activated stabilisers have been developed. The... 

The procedures described so far have all required a pore model to be assumed at the outset, usually the cylinder, adopted on the grounds of simplicity rather than correspondence with actuality. Brunauer, Mikhail and Bodor have attempted to eliminate the over-dejjendence on a model by basing their analysis on the hydraulic radius r rather than the Kelvin radius r . The hydraulic radius is defined as the ratio of the cross-sectional area of a tube to its perimeter, so that for a capillary of uniform cross-section r is equal to the ratio of the volume of an element of core to... 

The framework for the solution of porous media flow problems was estabUshed by the experiments of Henri Darcy in the 1800s. The relationship between fluid volumetric flow rate, hydraulic gradient, and cross-sectional area, yi, of flow is given by the Darcy formula ... 

Hydrostatic drives allow for selection of any travel speed up to the maximum without a concurrent variance in engine speed. The engine can be operated at the governed speed to provide proper operating speeds for auxiliary elements, eg, the threshing section of a combine. A frill range of travel speeds is available to adjust to terrain or crop conditions. Industrial applications for hydraulic systems and hydrostatic transmissions include the following (16) ... 

When the bulk containing the binder is uniform, it is compressed on pneumatic, hydraulic, or ram-type presses. Compression can be carried out in presses provided with suitably designed cavities or in metallic pans. The pans ate filled with the powder mass, and a plunger with a cross-sectional shape similar to that of the pan is used to compress the tablet. The resulting tablets ate commonly used with powder puffs or cosmetic bmshes. 

Noncircular Channels Calciilation of fric tional pressure drop in noncircular channels depends on whether the flow is laminar or tumu-lent, and on whether the channel is full or open. For turbulent flow in ducts running full, the hydraulic diameter shoiild be substituted for D in the friction factor and Reynolds number definitions, Eqs. (6-32) and (6-33). The hydraiilic diameter is defined as four times the channel cross-sectional area divided by the wetted perimeter. For example, the hydraiilic diameter for a circiilar pipe is = D, for an annulus of inner diameter d and outer diameter D, = D — d, for a rectangiilar duct of sides 7, h, Dij = ah/[2(a + h)].T ie hydraulic radius Rii is defined as one-fourth of the hydraiilic diameter. 

Isothermal Gas Flow in Pipes and Channels Isothermal compressible flow is often encountered in long transport lines, where there is sufficient heat transfer to maintain constant temperature. Velocities and Mach numbers are usually small, yet compressibihty effects are important when the total pressure drop is a large fraction of the absolute pressure. For an ideal gas with p = pM. JKT, integration of the differential form of the momentum or mechanical energy balance equations, assuming a constant fric tion factor/over a length L of a channel of constant cross section and hydraulic diameter D, yields,... 

Pressure drop data for the flow of paper stock in pipes are given in the data section of Stondords of the Hydroulic Jn.stitute (Hydraulic Institute, 1965). The flow behavior of fiber suspensions is discussed by Bobkowicz and Gaiivin (Chem. Eng. Sci., 22, 229-241 [1967]), Bugliarello and Daily (TAPPJ, 44, 881-893 [1961]), and Daily and Bugliarello (TAPPJ, 44, 497-512 [1961]). 

Hydraulic cone classifier V°W (M-F) Open cylindrical upper section with conical lower section containing slowly rotating mechanism. 0.6 to 1.6 400 im to 100 im (6 mm) 10 to 120 Not critical 2 to 15. 30 to 50 3 to 7.5 Used primarily in closed circuit grinding to reclassify hydrocycloue underflow... 

Skin friction loss. Skin friction loss is the loss from the shear forces on the impeller wall caused by turbulent friction. This loss is determined by considering the flow as an equivalent circular cross section with a hydraulic diameter. The loss is then computed based on well-known pipe flow pressure loss equations. 

In any mass transfer operation, the compositions of the liquid and vapor phases are assumed to follow the relationship illustrated by the column operating line. This line represents the overall calculated profile down the column however, the composition on each individual square foot of a particular column cross-section may vary from that represented by the operating line. These variations are the result of deviations in the hydraulic flow rates of the vapor and liquid phases, as well as incomplete mixing of the phases across the entire column. 

In this diagram the key features are A - Diffusion baffle this serves four roles. First to dissipate the velocity head, thereby improving the overall hydraulic characteristics of the separator. Next, to direct incoming flow downward and outward maximizing the use of the separator volume. Third, to reduce flow turbulence and to distribute the flow evenly over the separator s cross-sectional area. Finally, to isolate inlet turbulence from the rest of the separator. B- Internal chambers In the sediment chamber, heavy solids settle out, and concentrated slugs of oil rise to the surface. As the oily water passes through the parallel corrugated... 

Section 8.1 provided a description of a core melt. This section backs up to describe thermal-hydraulic calculations of the phenomena before, during, and after the accident, and other calculations to estimate the radioactive release from containment. In this accident physics cannot be analyzed separately from in-plant transport. 

The characteristic length L denotes the pipe diameter or the hydraulic diameter djjyj = 4A/F A is the cross-sectional area and P is the wet periphery). If the cross-section is not circular, or in the case of a plane, the length is measured in the flow direction. 

D , is the hydraulic diameter of one cross-section between the plates, calculated from... 

Water hammer (hydraulic shock) in pipelines is discussed in Section 9.1.5. It can also damage heat exchangers, and Figure 10-11 illustrates such an incident. 

It should be pointed out that the hydraulic diameter method does not work well for laminar flow because the shape affects the flow resistance in a way that cannot be expressed as a function of the ratio of cross-sectional area to wetted perimeter (Green and Maloney 1997). However, some flame arrester manufacturers use this method for noncircnlar flame arrester passages. 

This section provides a general overview of the properties of lake systems and presents tlie basic tools needed for modeling of lake water quality. The priiiciptil physical features of a lake are length, depth (i.e., water level), area (both of the water surface and of tire drainage area), and volume. The relationship betw een the flow of a lake or reserv oir and the volume is also an important characteristic. The ratio of the volume to the (volumetric) flow represents tlie hydraulic retention time (i.e., the time it would take to empty out the lake or reservoir if all inputs of water to the lake ceased). This retention time is given by the ratio of the water body volume and tire volumetric flow rate. 

For other length-to-diameter ratio, refer to Ref. [27]. For cross sections other than circular or square, use the hydraulic diameter ... 

For large towers (usually over 8 ft in diameter) check the hydraulic gradient for sections of the tray normal to liquid flow, adjusting each section by not more than one-half the gradient... 

Use velocity of aerated mass same as for cleair liquid. Rh = hydraulic radius of the aerated mass for cross-flow, ft cross section... 

Dj = outside diameter of inner tube, ft Dj = inside diameter of outer pipe, ft r[, = hydraulic radius, ft = (radius of a pipe equivalent to the annulus cross-section)... 

It is quite desirable to place water into an open-hole section prior to running a casing or liner siring and cementing. The water will provide a hydraulic head to hold back any formation gas in the open-hole section that could cause a fire hazard at the rig floor. 

Hydraulic lift must also be taken into account when using diamond bits and PDC bits. The weight-on-bit varies between 0 and 100,000 lb or 0 and 50 ton-force. The end effect is due to the differential pressure between the drill collar internal pressure and the external hydrostatic pressure. This differential pressure acts on the sub internal cross-sectional area. 

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