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Hammer bentley - Modeling a water open distribuiton network

Good Morning to all,

I have a case study in which the network is divided into two diferent branches which as it root on a pumping station.. Each branch as it own ramification that lead water to variou water reservoir.

I have the profile of each main branch and each ramification that lead to the reservoir, the pipe types and lenghts, and the reservoir heights. I have the volume of each reservoir but not the demand in each reservoir. I also have the pump head and flow for each branch.

Does anyone can help me with the hidraulic model for this case?   

Here is a schematic diagram of the network. 

How do i build my model in order to do surge analysis? Is this a open network ? Shoul i simulate each reservoir as a atmospheric discharge (need to know the flow)?

Many thanks to all who can help me.  

  • Best thing to do is take the on-demand HAMMER course. That will answer your questions and save you from other problems.

    https://learn.bentley.com/app/Public/ViewLearningPathDetails?lpId=111355

  • Hello Filipe,

    Based on the schematic you have set, you have to first develop a scheme (hydraulic model) in either WaterGEMS or WaterCAD software. When the hydraulic model is developed, you need to analyze it to understand how it is functioning (pressures in the system, pump operation, tank level fluctuations etc.) and check if these results are satisfactory.

    From the schematic, you need to model the "reservoirs" as tank elements and size them as per the specifications provided. Then determine which of these tanks need to be connected via pumps (based on elevation difference). Use the pipe element to model the connections between the reservoirs.

    In your schematic I don't see any "demand nodes' (points to which you need to supply water). If you know the supply to a "reservoir" you can input the same as "demand" for that "reservoir". This is because, WaterGEMS, WaterCAD and HAMMER, all use a demand driven approach to solve the hydraulic equations to calculate flow and pressure.

    Once the hydraulic model is prepared and analyzed, it can be brought into HAMMER. HAMMER, WaterGEMS and WaterCAD all use the same model file types (.WTG, .WTG.SQLITE) hence there is no need for conversion / import among them.

    For surge analysis what are the conditions you wish to simulate? HAMMER has a number of different scenarios such as pump shutdown, sudden valve closure etc. which can simulate conditions which develop transients in your model. Based on the transients (surge) generated, one can choose the correct surge mitigation equipment such as an air-valve, surge tank, hydropneumatic tank etc.

    Here are some articles which can help you understand all these products;

    Learning Resource Guide for new users of Bentley WaterGEMS and WaterCAD

    Learning Resource Guide for new users of Bentley HAMMER

    Get to know WaterGEMS, WaterCAD and HAMMER CONNECT Edition

    Hope this helps.


    Regards,

    Yashodhan Joshi

  • Hello Yashodhan Joshi,


    First of all, thank you for your answer. I should have made an introduction in which i explained why i need this supoort from you guys. I'm a environmental and civil engineer, and my job is to acess surge vessels volume in order to manufacture and suply such vessel to the contractors. I have been doing this job for some time now and we have always used Hammer for the vessel volume calculation (and other vessel caractheristics). So, despite never having used your forum before, i'm quite versed on using either the software or the forum. I have simulated water and wastewater pump stations and water distribuition networks. What a haven´t done is to simulate this kind of pump station and reservoir distribuiton.


    Once again, i'll try to explain what our client needs and what i think it would be a good aproach.


    Data i have: pump head and flow, elevation of all interest points and water levels, reservoir volumes, profile for each pipe that leads to each reservoir.
    Simulation required: surge analysis for the sudent pump stopage.


    Aproach and model: I will try to simulate this as as distribuition network (open, not closed) in which each reservoir will be simulated as a joint and will have a specific demand of flow.


    Data i think a don’t have: specific flow demand in each reservoir.


    Question: Can i simule the reservoir without the demand? Does it make na equal distibuion to all the reservoirs?

    Cheers,

    Filipe

  • Thanks for the clarification. I apologize that my initial response was oriented toward a beginner.

    Because this looks like a tree shaped (rather than looped system), you may not need to include pipes beyond the tanks in the model.

    Tanks are important for the way that they reflect the transient waves. You should treat them as tanks, not as junctions which reflect waves differently.

    However, the demand downstream of the tanks is not nearly as important as the tank water levels when determining the initial flows and the transient behavior.

    If I understand your question correctly, therefore, tanks will reflect/absorb the transient and unless there is a loop or bypass around them, the transient wave will not get around the tanks. Demand between the pumps and the tanks are important unless they are tiny. The flow distribution between the reservoirs is determined by the tank levels (HGL)  and pipe sizes.

    Answer Verified By: Sushma Choure 

  • I agree with Tom. You do not need to add a demand at the tank or at a junction next to or in place of the tank - flow will enter the tank based on energy balance. The tank Initial Elevations establish the known hydraulic grade at those points in the network, along with the known hydraulic grade at the reservoir that I assume you have upstream of your pumps. Based on this, and the pump characteristic curve (and pipe physical characteristics), HAMMER will be able to compute the initial conditions flow, velocity, pressure etc. The flow into the tanks will be the flow necessary for those known hydraulic grades to be true. 

    This all assumes that the pipes connect to the bottom of the tank. If the pipes connect to the top of the tank and water spills into it, then you can model them using the Discharge-to-Atmosphere. You can find some guidance on that here (see paragraph at bottom):

    Modeling top fill tanks and throttling inlet valves

    You can then configure the pump's transient properties as you have done before, to establish the transient event.


    Regards,

    Jesse Dringoli
    Technical Support Manager, OpenFlows
    Bentley Communities Site Administrator
    Bentley Systems, Inc.