The ability to analyze different alternatives for protection against water hammer effects in a water pipeline system, either supplied by gravity or supplied by pumping, is one of the main features of Ariete, our water hammer software, which through the “Analysis Scenarios” creation allows comparing the results, obtained in each of these scenarios, simultaneously.
In this article, we present the characteristic aspects of Scenarios Management in Ariete, and we’ll implement alternatives for protection against water hammer through an example of a pumping pipeline which suffers an accidental stoppage for power supply failure into the respective pumping station.
By default, when you create a new project in Ariete, the Pipeline and its upstream and downstream devices are created inside an analysis scenario called “Base Scenario,” which will be active while a new one is not created.
The idea behind the Base Scenario is that, with it, the Original pipeline system, i.e.: with no water hammer control devices, will be modeled, with it being possible to change its name and description from the Scenarios Menu → Edit Active Scenario:
For this example we’ll modify the name to “Original System.”
Thus, the Original System scenario will contain the pumping pipeline system with no modifications (no control devices against water hammer effects), as we saw in this Article.
New Scenario Creation – One Way Water Surge Tank
We wish now to observe what effect would occur when installing a One Way Surge Tank in the control point at 5373 m pipeline’s chainage and, to do so, a new scenario called “One Way S.T.” will be created through the Create New Scenario option at Scenarios menu.
Once created, this scenario will automatically become the Active one, which is confirmed from the list at the Ariete’s main toolbar:
By becoming an Active scenario, any modifications (adding water hammer control devices) will be effective and visible only in that scenario, and the remaining scenarios remain unchanged.
Thus, a One Way Surge Tank is added to this scenario (in this article we explain how to add interior devices) by entering the following data:
When closing all the opened dialogs, the water surge tank symbol will be shown in Ariete’s Main Window:
When performing the Unsteady calculation, we’ll obtain the results for our new Scenario:
Comparing Results Between Scenarios
Having more than one scenario (in our case, two), we only need to activate the “Compare results with other Scenario” checkbox in the Results panel, to enable the list of existing scenarios in this Project, and then select and click on the respective scenario to compare. In our case, it will be the Original System scenario:
In addition, by keeping the “Compare results with other Scenario” option active (checked), a results charts for each control point will contain results for the selected scenarios besides the actual one:
Finally, it should be noted that Scenarios creation for Water Hammer calculation and analysis in Ariete has the following considerations:
- The maximum number of additional scenarios to the Base one that can be created in Ariete is three (3).
- When a new scenario is created, it must be taken into account that the characteristics of the Active scenario will be copied to the new one. In our example, if we would create a new scenario having the “One Way S.T.” as active, the new scenario will include an interior device at chainage 5737, the one way surge tank. So, if you want to create a scenario without water hammer control devices, you must first change the Active Scenario (to Original System in this example) and then create the new scenario.
- To remove the results visualization of all selected scenarios at the same time, just uncheck the “Compare results with other Scenario” checkbox. Of course, when checked again, all selected scenarios results will be shown at once.