This article will explain the step by step methods for modeling the Rigid Strut using software Caesar II.
1 - Find out the direction in which restriction of movement is required (Assume X direction) and location of the strut installation. For reducing thermal loads to be carried by rigid struts it is preferable to choose thermal null points if feasible.
2- Double click on restraints check box in Caesar spreadsheet and model restraint X with 0 mm gap and with no friction. Keep stiffness K1 box blank.
3- Run Caesar Analysis and found out the force in that node.
4- Enter into any catalogue (like C&P, Lisega etc) and select appropriate rigid strut depending on that force (For your reference strut selection table has been reproduced in Fig. 1 from C&P Catalogue).
5- Obtain the stiffness value for the strut from the catalogue and enter this value in restraint stiffness (K1) which u left blank in initial stage.
Note: Rigid Struts are used in Turbine and Compressor connected lines near the nozzle connections to take the advantage of very less friction. Otherwise struts can be used as a substitute for guide supports where structure is not available for using standard guides.
1- Slug Flow is typical two phase flow where a wave is picked up periodically by the rapidly moving gas to form a frothy slug, which passes along the pipe at a greater velocity than the average liquid velocity.
2- In this type of flow, slugs can cause severe and, in some cases, dangerous vibrations in piping systems because of the impact of the high-velocity slugs against fittings such as bend, Tee etc.
3- Slug flows generate dynamic fluid forces, which may induce structural vibration.
4- Excessive vibration may lead to component failures due to fatigue or resonance.
5- Such vibration problem may be avoided by thorough analysis, preferably at design stage.
6- Two types of Analysis Methods are prevalent:
a) Static Analysis
b) Dynamic Analysis
a) Static Analysis
b) Dynamic Analysis
7- Examples of Slug flow:
a) Vacuum Transfer Lines
b) Condenser Outlet Lines
c) Re-boiler Return Lines
d) Fired Heater outlets
e) Boiler Blow down lines.
a) Vacuum Transfer Lines
b) Condenser Outlet Lines
c) Re-boiler Return Lines
d) Fired Heater outlets
e) Boiler Blow down lines.
Slug force is equal to the change in momentum with respect to time.