Hydraulic equivalent diameter

Hydraulic diameter, or equivalent diameter, in. Orifice diameter, or nozzle opening, in. 

The hydraulic equivalent diameter is related to the actual nozzle diameters by... 

The above hydraulic equivalent diameter is close enough to the one obtained with Equation 4-171. Therefore, the bit should have three - -in. diameter nozzles. 

D = Inside diameter of pipe, ft DH = Hydraulic diameter, ft d = Inside diameter of pipe, in. = d de = Equivalent or reference pipe diameter, in. dn = Hydraulic diameter, or equivalent diameter, in. dQ = Orifice diameter, or nozzle opening, in. 

Calculate the shell-side equivalent diameter (hydraulic diameter), Figure 12.28. For a square pitch arrangement ... 

It is common practice to define a hydraulic equivalent sphere as the sphere with the same density and terminal settling velocity as the particle in question. For a spheroid in creeping flow, the hydraulic equivalent sphere diameter is 2a- E/A and thus depends on orientation. 

For higher Re, departure from the Oseen drag increases with increasing aspect ratio. It is common practice to determine a hydraulic equivalent diameter... 

For a circular duct, the hydraulic diameter is equal to its physical diameter. For a noncircular duct, it is convenient to use the hydraulic diameter to substitute for the characteristic physical dimension. However, for ducts with very sharp corners (e.g., triangular and cusped ducts), the use of the hydraulic diameter results in unacceptably large errors in the turbulent flow friction and heat transfer coefficients determined from the circular duct correlation. Other dimensions have been proposed as substitutes for hydraulic diameter. These equivalent diameters, provided for specific ducts only, will be presented elsewhere in this chapter. 

The definition of hydraulic (equivalent pore) diameter de for a capillary tube of uniform cross section is... 

In what follows we derive an empirical relation for the permeability, known as the Kozeny-Carman equation, which supposes the porous medium to be equivalent to a series of channels. The permeability is identified with the square of the characteristic diameter of the channels, which is taken to be a hydraulic diameter or equivalent diameter, d. This diameter is conventionally defined as four times the flow cross-sectional area divided by the wetted perimeter, and measures the ratio of volume to surface of the pore space. In terms of the porous medium characteristics. 

The Engineering ToolBox. Hydraulic Diameter, http //www.engineeringtoolbox.com/ hydraulic-equivalent-diameter-d 458.html (accessed April 10,2015). 

The friction loss in long straight channels or conduits of noncircular cross section can be estimated by using the same equations employed for circular pipes if the diameter in the Reynolds number and in the friction factor equation (2.10-6) is taken as the equivalent diameter. The equivalent diameter D is defined as four times the hydraulic radius r . The... 

In Table 1 the results obtained with 5 prosthetic valves (HK 21, 23, 25, 27, 29 mm TAD) are shown. Water at room temperature was the circulatory fluid. Steady retrograde flow is not an icreasing function of the diameter, meaning that the working tolerances affect very much the clearance between disc and stent. It is possible, by knowing both pressure and flow rate across the valve, to calculate a hydraulic equivalent diameter which shows the size of the disc--stent clearance. The ratio between such a diameter and the nominal one provides a figure of merit for the comparative evaluation of different prostheses. 

The unit reported by the authors distributes an inlet flow (such as 3001/h) iuto 256 outlet flows evenly distributed over a square cross-section of 6 X 6cm. The 256 flow paths are all hydraulically equivalent. The distribution of channel diameters is optimised according to Murray s criterion, with a scaling ratio of 2. The device was manufactured by stereolithography in the laboratory of one of the partners. 

In the expressions above, Dhe and Dhy are, respectively, the heated and hydraulic equivalent diameters, defined by the relations... 

It is normal practice to consider a partially full gravity flow pipeline as a full flow pipeline of a smaller, equivalent diameter. The equivalent diameter matches all the hydraulic characteristics of the larger, partial flow gravity pipeline. The velocity, GPM flow rate and slope are identical in each case. The equivalent diameter is four times the hydraulic radius. The hydraulic radius for partial flow gravity pipelines is defined as the ratio of the cross-sectional flow area divided by the wetted perimeter. 

Re using the equivalent diameters defined in the following. This situation is, by arbitrary definition, opposite to that for the hydraulic diameter used for turbulent flow. 

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. 

To calculate the thermal plume, the cube can be presented as a cylinder with a diameter equivalent To the hydraulic diameter of the top of the cube ... 

Eor noncircular apertures, the equivalent hydraulic diameter should be used. Eor crimped metal ribbon elements, the equivalent hydraulic diameter of a right isosceles triangle is 0.83 times the crimp height, and the thickness (width) should be at least 0.5 inches (EISE 1980). 

Equivalent diameter and hydraulic radius for non-circular flow ducts or pipes... 

The volumetric equivalent diameter, d,. in., is again calculated on the basis of 4X the hydraulic radius see Figure 10-56. 

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)... 

Barnett confirmed that dh does not fully describe the cross-sectional geometry for burn-out in an annulus, and he decided to introduce as an extra term—the wetted equivalent diameter, i.e., the hydraulic diameter dw = d0 — di. The final expressions found suitable for A, B, and C are... 

The connection that has been shown in Section VIII to exist between burn-out in a rod bundle and in an annulus leads to the question of whether or not a link may also exist between, for example, a round tube and an annulus. Now, a round tube has its cross section defined uniquely by one dimension—its diameter therefore if a link exists between a round tube and an annulus section, it must be by way of some suitably defined equivalent diameter. Two possibilities that immediately appear are the hydraulic diameter, dw = d0 — dt, and the heated equivalent diameter, dh = (da2 — rf,2)/ however, there are other possible definitions. To resolve the issue, Barnett (B4) devised a simple test, which is illustrated by Figs. 38 and 39. These show a plot of reliable burn-out data for annulus test sections using water at 1000 psia. Superimposed are the corresponding burn-out lines for round tubes of different diameters based on the correlation given in Section VIII. It is clearly evident that the hydraulic and the heated equivalent diameters are unsuitable, as the discrepancies are far larger than can be explained by any inaccuracies in the data or in the correlation used. 

For the heat transfer for fluids flowing in non-circular ducts, such as rectangular ventilating ducts, the equations developed for turbulent flow inside a circular pipe may be used if an equivalent diameter, such as the hydraulic mean diameter de discussed previously, is used in place of d. 

In continuous flow systems, the expenditure in mechanical energy necessary to run a process is directly proportional to the pressure drop over the system. Hence the pressure drop is an important figure determining the operating costs of a device. After having verified the chemical equivalence of the two reactor types introduced above, the question arises of whether using a micro-channel reactor instead of a fixed-bed reactor allows a decrease in the pressure drop. In order to estimate the pressure drop in the fixed-bed reactor, the Carman-Kozeney hydraulic diameter model (see, e.g., [116]) was used ... 

In some texts the equivalent (hydraulic mean) diameter is defined differently for use in calculating the heat transfer coefficient in a conduit or channel, than for calculating the pressure drop. The perimeter through which the heat is being transferred is used in place of the total wetted perimeter. In practice, the use of de calculated either way will make... 

The heat transfer coefficient to the vessel wall can be estimated using the correlations for forced convection in conduits, such as equation 12.11. The fluid velocity and the path length can be calculated from the geometry of the jacket arrangement. The hydraulic mean diameter (equivalent diameter, de) of the channel or half-pipe should be used as the characteristic dimension in the Reynolds and Nusselt numbers see Section 12.8.1. 

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