Transient Analysis for hydropower project

Hello Amits,

The headloss through the "orifice between pipes" is based on the pair of pressure drop and corresponding flow, which translate to a discharge coefficient behind the scenes. You would normally select a flow that's in the range of what you'd typically see through the valve, and the corresponding pressure drop that you'd see at that flow. If you have the orifice diameter, perhaps you could calculate the pressure drop (in terms of feet or meters) using the orifice equation for that selected flow.

This is a new problem in Hammer. I have modelled an orifice between two pipes which are in a branch line. The main input parameters for orifice are pressure drop and flow through the orifice.  In practical terms, how do i specify the dia of the orifice for that pressure drop to take place. The branch pipe line has a valve at the end and i want to restrict the maximum pressure at the valve during load rejection in the main line.

It sounds like the software can't find a solution for the model setup you have. You should submit the model to tech support so that they can help you figure out why: appsnet.bentley.com/srmanager

Regards,

Mal

Another small issue with theabove model in Hammer. I have modelled the turbines as GPV for a combination case of load acceptance followed by load rejection. When i input the load acceptance time as 250 sec, the model runs fine. But reducing the load acceptance time to 20 sec gives an error-                                                         " 45523 "Base" "Surge Tank" "52" "ST-1" (N/A) "The root sought is not obtained for iteration 1." Transient Engine

Can you pl. let me know the reason for this error and what exactly does it mean?

Thanks Mal!!

Hi,

You can find this information in the detailed output report. To see these results you should:

1. Open the Properties pane for the surge tank and set the "Report Period (Transient)" value to a number greater than zero (10 is a good starting point)

2. Make sure that 'Generate Detailed Reports' is TRUE in the Transient Solver calculation options

4. Still in the calculation options, make sure that the surge tank is included in the set of "Report Points"

3. Compute

4. Click Report > Transient Analysis Reports > Transient Analysis Detailed Report. Towards the end of the report you will see detailed results for the surge tank (time, water level, head, inflow, spill rate).

(Note: we are planning to make these results a little more accessible in a future release).

Regards,

Mal

I have modelled a simple circular Surge Tank with an orifice as a surge protection device in the water conductor system. The results of the transient simulation gives pressure and maximum head at the surge tank node. However i am more interested in the maximum or minimum surge levels. The pressure head at the surge tank node shall ideally be equal to the maximum surge level but may not be same depending on the orifice size selected. Software such as WHAMO gives the maximum pressure and also the maximum surge level.

My question is - How to know the surge levels in the surge tank and whether the maximum head at surge tank node is equal to maximum upsurge level?