Losses in fittings

The flow in pipe fittings, e.g. bends and valves, is generally too complex to determine theoretically. For turbulent flow, these minor losses are approximately equal to the square of the flow velocity. Thus, we define a loss coefficient, K, 

These minor fitting losses can also be expressed in terms of an equivalent length of straight horizontal pipe, 4, giving the same frictional loss. 

Fitting n, number of pipe diameters K, number of velocity heads 

Therefore, the total pressure or head loss due to friction in pipework due to the pipe and fittings is given by 

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Mechanical energy balance, assuming no losses in fittings, no change in elevation, and so on. 

Since the restricted model is quite nonlinear, it would be quite cumbersome to estimate and examine the loss in fit. We can test the restriction using the unrestricted model. For this problem,... 

If A2 A, e.g. flow from a pipe into a large vessel or reservoir, K 1 Thus the exit loss from a pipe into a large vessel is 1 velocity head, i.e. all kinetic energy in the flowing fluid is lost when it comes to rest after entering a large vessel. This is the value reported later in Table 5 for an Exit Loss. Losses in fittings are described in more detail in the next section. 

The flow of non-Newtonian fluids in circular and non-circular ducts encompassing both laminar and turbulent regimes is presented in Chapter 3. Issues relating to the transition from laminar to turbulent flow, minor losses in fittings and flow in pumps, as well as metering of flow, are also discussed in this chapter. 

Frictional losses in mechanical-energy-balance equation. The frictional losses from the friction in the straight pipe (Fanning friction), enlargement losses, contraction losses, and losses in fittings and valves are all incorporated in the F term of Eq. (2.7-28) for the mechanical-energy balance, so that... 

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