![]() ![]() ![]() Resistance Coefficient Method – K Method – Excess head In the following section these methods are summarized in the order from the simplest to the most sophisticated. There are several methods how to calculate head loss from fittings, bends and elbows. K is the sum of all of the loss coefficients in the length of pipe, each contributing to the overall head loss. Like pipe friction, the minor losses are r oughly proportional to the square of the flow rate and therefore they can be easy integrated into the Darcy-Weisbach equation. The data, especially for valves, are somewhat dependent upon the particular manufacturer’s design. The minor losses are commonly measured experimentally. For relatively short pipe systems, with a relatively large number of bends and fittings, minor losses can easily exceed major losses (especially with a partially closed valve that can cause a greater pressure loss than a long pipe, in fact when a valve is closed or nearly closed, the minor loss is infinite). Such losses are generally termed minor losses, although they often account for a major portion of the head loss. These additional components add to the overall head loss of the system. In industry any pipe system contains different technological elements as bends, fittings, valves or heated channels. ![]() If there is no change in elevation head (the pipe lies horizontal), the decrease in kinetic head must be compensated for by an increase in pressure head. Since the outlet velocity is less than the inlet velocity, the kinetic head of the flow must decrease from the inlet to the outlet. If this pipe undergoes a gradual expansion in diameter, the continuity equation tells us that as the pipe diameter increases, the flow velocity must decrease in order to maintain the same mass flow rate. Thus, Bernoulli’s equation states that the total head of the fluid is constant.Ĭonsider a pipe containing an ideal fluid. The sum of the elevation head, kinetic head, and pressure head of a fluid is called the total head. It is the height in feet that a flowing fluid would rise in a column if all of its kinetic energy were converted to potential energy. Kinetic potential – Kinetic head: The kinetic head represents the kinetic energy of the fluid.Elevation potential – Elevation head: The elevation head represents the potential energy of a fluid due to its elevation above a reference level.ρ w: density of water assumed to be independent of pressure Pressure potential – Pressure head: The pressure head represents the flow energy of a column of fluid whose weight is equivalent to the pressure of the fluid. ![]() There are four types of potential (head): Therefore the characteristics of all pumps can be usually read from its Q-H curve (flow rate – height). This head is usually referred to as the static head and represents the maximum height (pressure) it can deliver. The units for all the different forms of energy in the Bernoulli’s equation can be measured also in units of distance, and therefore these terms are sometimes referred to as “heads” (pressure head, velocity head, and elevation head). In fluid dynamics, head is a concept that relates the energy in an incompressible fluid to the height of an equivalent static column of that fluid. It can be used to determine a hydraulic gradient between two or more points. In general, the hydraulic head, or total head, is a measure of the potential of fluid at the measurement point. ![]()
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