K Factor Loss Model

AFT Impulse models K factor component losses according to the following equation:

(1)

where K is commonly referred to as the loss factor.

Table 1 lists the sources for the loss models used in AFT Impulse. The losses implemented directly in the code were chosen on the basis of ease of use. Many loss factor types are functions of the flow, and thus too general to be easily incorporated.

Table 1: Loss model references

Junction Type References
Bend Crane 1988, A-29
Miller 1990, 207-209
Area Change Crane 1988, A-26
Idelchik 2007, 246 & 254
Orifice Idelchik 2007, 258-259 & 262
Screen Idelchik 2007, 598
Tee/Wye Idelchik 2007, Chapter 7
Miller 1990, 315-316 & 323
Valve Ingersoll-Rand 1970
Crane 1988, A-29

Crane (1988)Crane Co., Flow of Fluids Through Valves, Fittings, and Pipe, Technical Paper No. 410, Crane Co., Joliet, IL, 1988. offers good general purpose correlations for modeling irrecoverable losses in pipe systems.

Another lesser known source of loss factor information is Idelchik (2007)Idelchik, I. E., Handbook of Hydraulic Resistance, 4th edition, Begell House, Redding, CT, 2007.. This reference is indispensable for the engineer who must make detailed hydraulic assessments of pipe systems in which so-called minor losses play a significant role. The reference is voluminous in scope and full of tables, charts and equations for calculating loss factors for almost any pipe arrangement.

Miller (1990)Miller, D. S., Internal Flow Systems, 2nd edition, Gulf Publishing Company, Houston, TX, 1990. is another reference offering good general purpose hydraulic data.