Hydraflow Storm Sewers 2014 HGL Problem

[ashroads]

I'm running C3D 2014 and using Hydraflow Storm Sewers

I have an existing storm drain system consisting of Outfall --> MH --> MH --> Bend --> Inlet. I have a Qpeak of 258 cfs determined from another source (I am only entering Known Q values, not entering any information for Q=CiA). All I want to do is determine the HGL for this existing system (I am not using any design aspects of the program).

When I run the model, I get no errors, but my energy loss from friction is zero and my depth seems to default to critical depth. I have changed my Starting HGL while solving to normal, critical & (dc+D)/2, but nothing changes. If I shrink my downstream pipe sizes to force pressurized flow, the friction slope populates, but that is the only way I can get it to calculate.

Any thoughts or suggestions? I attached the file... had to change the extension to .txt to upload. Change it back to .stm to open.

Thanks!

[fcernst]

I wouldn't trust that. Hydraflow is just carrying the same HGL elevation across the structure when Inlet Control is checked. See first image.

The second image below shows the system in StormCAD with only 200 cfs. You can see the inlet control headwater being created and the subsequent hydraulic jumps.

In StormCAD I didn't have to manually select to check Inlet Control either.

 

[Matt.Anderson]

Fred -

Thanks for posting the StormCAD results.

In both cases, StormCAD and Hydraflow is calculating the pipe to be a supercritical flow condition.  It appears we slightly disagree with that value at the upstream end (within 0.01 feet in either case)

FHWA HEC-22 guidelines suggests "If supercritical Flow occurs, pipe and access losses are not carried upstream".  This is why there is no junction loss in his model.

StormCAD appears to add the junction losses in.

Hydraflow will show something different will be in the profile of the pipe.  It currently draws the critical depth in the pipe until it hits the hydraulic jump.  The supercritical depth is not shown.

[fcernst]

Matt,

Hydraflow is giving varying results if I choose "Correct EGL Discrepancies" in the Design Codes:

The first image below shows the profile with the HGL values from yesterday. It just flatlines across the structures, not picking up any Inlet Control headwater.

The second and third image shows the profile and HGL values with "Correct EGL Discrepancies" enabled in the Design Codes.

1

[ashroads]

Thanks for the replies Matt and Fred. Here is what I can gather so far:

• The friction and junction losses not carried upstream during supercritical flow - this is OK and what the program is supposed to do per HEC-22.
• The program is using critical depth everywhere (except for control point at outlet) - I don't understand why it is doing this... per HEC-22 (see steps 8, 9, 10) normal depth should be assumed and then continue calculations. The attached screenshot is the only thing I can find in the help related to this, however I do not know if it applies (I have no indication from the program that the energy equation is not balanced and it doesn't look like the program calculated a supercritical profile).

I have support and have opened a ticket with Autodesk, but haven't had a firm answer yet. Will keep you guys updated.

Andrew

[fcernst]

The StormCAD profile seems to more resemble the situation shown and discussed in the attached research paper.

[fcernst]

My fear and concern has been confirmed by Autodesk Support today.

Hydraflow is not using the correct HEC-22 methodology. Support states that the software uses the 2001 proceudre. The HEC 22 EGL/HGL analysis procedure was significantly updated in 2009 with HEC 22 Version 3.  That was five years ago now. This is unacceptable.  Why has this not been addressed?

Secondly, HDS 5 is not the correct Inlet Control methodology to use for storm sewers due to manholes and structures posing different entrance scenarios than culverts. The 2009 HEC 22 contains the correct Inlet Control equations, based off of extensive laboratory studies and research conducted to update the procedure,  to use to test for submerged and unsubmerged inlet control. The update was required due to the failure of the old method to address situations where there is supercritical flow in the outflow conduit. That is the exactly case here with the OP's model scenario.

Lastly, Hydraflow doesn't do anything when its HDS 5 inlet control method is activated in Design Codes. It simply just translates Critical Depth across the manhole. It does this even at the almost 90 degree deflection angle at the bottom of this sewer run.  The engineer needs to especially determine at this location if this is a dangerous flow condition resulting in geyser action at this manhole.

Support now confirms that the Inlet Control option is not working in the software. Again, this is still the incorrect Inlet Control method to use.

These type of items are what our Subscription dollars are supoose to be addressing for us.

Please give your feedback to management here:

http://usa.autodesk.com/adsk/servlet/index?siteID=123112&id=1109794

[ashroads]

Just to expand on what Fred has contributed... here is the email from Autodesk Support. It appears that there are quite a few things that need to be remedied/updated with the software for this situation and that many of them have been escalated to development:

Dear Andrew,

Thank you for your patience and for the various inputs and comments. It appears your issues and model are the same with that of Fred Ernst of Ernst Engineering and likewise I have informed him that;

We have reviewed our concerns further and figured that, Step 16 he mentioned is from the 2009 version of HEC-22. However, Hydraflow has not been updated to comply with 2009.

Energy Loss computations are rooted in the 2001 version of HEC-22, and the Composite Energy Loss Method which assumes critical depth in the junction when supercritical flow occurs.

With regards to the Junction HW elevation when Inlet Control is selected, we have also found some issue with that and I will document and escalate it to development for correction.

Further, the supercritical warnings is available in the Interactive Feature however, I will also document and escalate the lack of supercritical depth to the development team.

I apologize for the inconvenience this may cause, however as per process I will be closing this case and this does not mean your case is forgotten, but it is in pending status while the development team works on this issue. Please do not hesitate to contact us in the future with any and all questions you may have.

[sturner7277]

Has this been issue been resolved in the 2017 version??