Time history for the hydropneumatic tank

Question

Dear Sirs, 
 I'm looking for tool in Hammer which makes the graph on the Figure below. It shows flow during the time in and out from hydropneumatic tank HT. It is taken from the materials from paper of Bentley. 
 And if my version 8i has this tool, is there an option to see the current volume in the HT?

Scott Kampa · Accepted Answer

Hello Boyan, 
 You can create these from the Transient Results Viewer. There is a Time History tab. You will need to include report points for elements in your model. This is done in the transient calculation options. You have options to include all elements as report points or a selection of them. This link includes general information on doing this. 
 To view results like the volume in a hydropneumatic tank, you can do this with the Extended Node Data tab in the Transient Results Viewer. This feature is available in HAMMER V8i SELECTseries 5 or later. If you have an earlier version, you would need to use the Transient Analysis Detailed Report. The link above includes these steps as well. You will need to include a Report Period in the hydropnematic tank properties to be able to see results in the Extended Node Data tab or the Transient Analysis Detailed Report. 
 Regards, 
 Scott

Jesse Dringoli · Answer

Hi Boyan, 
 Your tank is set to use a bladder (has bladder = true) in which case HAMMER assumes that the pressure inside the full bladder is equal to the "preset pressure" (98 Kpa in your case) before the tank is installed and subjecting the tank to pipeline. Meaning, it determines the gas law relationship based on that preset pressure at the tank full volume. The bladder is then compressed based on that relationship along with the initial conditions pressure. This determines the starting gas volume at the first transient timestep. This is also why changes to the full volume impact the results, because they change the gas law relationship (if you keep the preset pressure the same). 
 For more information on how this works (including illustrations), see the "bladder" sections in the following article: Modeling Reference - Hydropneumatic Tanks

Boyan Borisov · Answer

Hi Jesse, 
 Thanks, I understood the situation. I have one small secondary question. Which volume is given in the second column on Figure 2 and 3, after calculation based on initial conditions? I thought that it is the volume of water in the bladder, but after your explanation about main question I doubt.

Jesse Dringoli · Answer

Boyan Borisov said: Which volume is given in the second column on Figure 2 and 3, after calculation based on initial conditions? 
 It is the volume of gas in the tank - when the tank is connected to the system and subjected to system pressure, the gas/air in the tank compresses to the size that you see in the first row of those reports. If your tank is the "air in bladder" type, then it is the volume of air inside the bladder during the transient simulation and if it is the "water in bladder" type, it is the volume of air outside the bladder (but in the tank). There are illustrations in the article previously mentioned to show the difference.

Time history for the hydropneumatic tank

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