next assumption is that because the system uses gases, the effect of variation in potential height at a duct section is so small relative to the other neglected. This assumption is the change in elevation effect any other section. terms that its effect is extenied further to include at any section relative to Alternate forms of the Bernoulli Equation are obtained by multiplying through by either c/ or p. Of interest to gas flow and duct design is the form obtained by multiplying through by p. Applying the above assumptions the resulting equation is:
pv2/29c +P = constant
(egn 2.2)
In this form the constant has units of foot pound force/ feet 3 and expresses the energy per unit volume flow rate.
It reduces to pound force/feet2 or pressure. Each term in the expression is given a name. The velocity term is the velocity presure, p is the static pressure, and the constant is the total pressure. In words, the total pressure at a the sum of the velocity pressure and the static point is pressure.
C. MODIFIED BERNOULLI EQUATION
Although equation 2.2 was derived for flow along a streamtube of an ideal frictionless flow it can be extended to analyze flow through ducts in real systems by applying the First Law of Thermodynamics. A good development of the application of the First Law of Thermodynamics to pipe flow is found in [Ref. 2]- It results in the modified Bernoulli Equation (2.3). Equation (2.3) incorporates all the assump- tions so far and includes the term Apt. The flow resistance in a system with a real fluid between stations 1 and 2 is represented by the total pressure loss, Apt-
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