K Factor Loss Model
AFT Fathom models K-factor component losses according to the following equation:
where K is commonly referred to as the loss factor.
Table 1 lists the sources for the loss models used in AFT Fathom. 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 (see the Resistance Curve topic for flow dependent loss applications).
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.
