Question of loop simulation in PWR using THM #28116
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Hi all, I'm simulating a very simple PWR loop using THM. The loop does not contain the heat source. The distribution of pressure and velocity is shown below. The input file is simple_pwr_loop.txt. As in typical PWR, the pressure drop through the pump should be 0.5MPa, which is good in this simulation. But the velocity in the loop should be 5m/s. In this simulation, it is only 0.5 m/s. I do not know the reason. I tried to change the area of the pipe, but the results did not change. How to let the pressure drop keep at 0.5MPa, and increase the velocity to 5m/s at the same time? Thanks! |
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Replies: 3 comments 10 replies
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Could you please kindly give me some suggestions? Thanks! |
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Not sure there is an easy solution there. The pressure drop is tied to the velocity since it partially comes from friction. You could mess with the pipe friction factors, maybe use a different model for the roughness, to reduce pressure drop. The area of the pipe is a variable as well. Maybe plot the results of pressure_drop as a function of velocity and see if some part of the curve works for you |
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It appears you are not running close to a steady state. I see that the pressure drops sharply at the junction of your loop with the pressurizer, and this is overshadowing any of the other pressure drops in your system, like by gravity and friction. Running longer decreases this pressure drop. See if you can get to steady state. Perhaps you can try ramping the pump head from zero to your end value to ease the transient. Ultimately, your pressure drops in your loop need to sum to your pump head. Contributions will be from friction, junctions, and gravity, so your ability to change the steady velocity will be based on the friction factor, since that's the only one you can change. |
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I wouldn't necessarily adjust the friction factor to eliminate that pressure drop at the junction. Just model your system as closely as you're able to your actual reference system: