Use of controls or patterns hammer

Question

Hello 
 I'm doing a simulation based on the rapid closure of a valve ball, but I have some problems pressure drop is not as expected. I pretend closing it with a pattern of operational valve. my question is if corecto for such situations indicate the valve closure by a pattern or perhaps better control. because using the pattern gives me a sobresi&oacute;n 10m when I experimentally comes only 5m. My scenario has two types of pipe not know if that also affect the calculation of wave speed. 
 
 I would greatly appreciate if you can guide a bit.

Sushma Choure · Answer

Hello Claudia, 
 Controls are not functional in Hammer, as its a transient analysis software. But you can use the patterns, below is information on using patterns in Hammer. 
 http://communities.bentley.com/products/hydraulics___hydrology/w/hydraulics_and_hydrology__wiki/9735.how-do-i-mimic-a-control-in-hammer

Jesse Dringoli · Answer

Claudia, 
 If you've used a transient operating rule on your valve and the closure results are not as you expect, it could be due to a problem with the valve configuration. Here are two related articles that may help: 
 Gradual closure not occurring when using valve operating rule 
 Modeling Reference - Valves [TN]

Jesse Dringoli · Answer

Claudia, 
 
Is your valve a FCV? If so, this message is expected in cases where the flow through the valve is less than the setting. This is explained here: 
 
 communities.bentley.com/.../23115.what-is-the-meaning-of-the-notification-valve-cannot-deliver-flow-with-regards-to-a-flow-control-valve-fcv 
 
Basically this is just an informational message to let you know that the valve is fully open - it doesn't need to throttle to reduce the flow since the flow is already less than the setting. 
 
If the valve you're trying to model is not actually a flow control valve that automatically opens/closes to maintain a set flow, then I would suggest morphing it into a TCV. You can read more about the use of different valve types for a valve closure in HAMMER in the second link I sent in my last email: 
 
 communities.bentley.com/.../3438.modeling-reference-valves-tn

Jesse Dringoli · Answer

Hello Claudia, 
 
I'm not quite sure I understand your question. Are you asking what other factors influence the behavior of a valve during a transient simulation, in addition to the Operating Rule? 
 
In general, the hydraulics of the closure of a valve in HAMMER are based on the Operating rule (pattern of relative closure over time) and the selected Valve Characteristics (which defines the discharge coefficient for each relative closure percentage). The valve characteristics are also used in conjunction with the fully open discharge coefficient (when using discharge coefficient or valve characteristics curve as the valve type) or minor loss coefficient (when using headloss coefficient as the valve type). Further, the initial status of the valve effects the initial position and headloss, which should match the starting position of the Operating Rule pattern. You can read more about this in the second link I sent in my previous reply. 
 
I see you still mention "FCV" - again, if the valve in question is simply controlled by a pattern, then it would be best to model it as a TCV. If you use a FCV, the position of the valve (and headloss) in the initial conditions can be based on the flow setting that you enter (if calculated status is Active), in which case you'll need to make sure that 
 
Note that FCVs will not dynamically throttle to meet the desired flow setting during the transient simulation. The FCV is assumed to be in a fixed position during the transient. See more on that here: 
 
 communities.bentley.com/.../6905.modeling-existing-valves-as-throttle-control-valves-in-hammer 
 
 communities.bentley.com/.../27283.what-is-the-difference-between-a-throttle-control-valve-tcv-and-a-flow-control-valve-fcv