The discussion revolves around the behavior of a compressible fluid passing through a convergent-divergent nozzle, specifically focusing on the velocity of the fluid at the outlet given certain inlet conditions and pressure ratios. The conversation touches on theoretical aspects of fluid dynamics, including compressible flow, shock waves, and the implications of various parameters on flow characteristics.
Participants express multiple competing views regarding the expected outlet velocity and the feasibility of achieving it under the given conditions. There is no consensus on the calculations or assumptions presented, and the discussion remains unresolved regarding the specific outcomes and implications of the nozzle setup.
Limitations include the undefined fluid type, temperature, and the ambiguity surrounding the parameters of the problem. The discussion highlights the complexities of compressible flow and the need for precise definitions to arrive at a solvable scenario.
This discussion may be of interest to those studying fluid dynamics, particularly in the context of compressible flow and nozzle design, as well as engineers and researchers working with fluid systems in various applications.
Right.T C said:Especially when the velocity at the throat is choked and inlet pressure is sufficient, right?
russ_watters said:Note that he said divergent only this time, so for this to be true you have to assume there's still/also a convergent section and a large enough reservoir feeding it. And the 5bar is the pressure at the throat, not the reservoir.
The OP didn't say the throat flow was choked in the scenario given in post #21 (or even the original scenario).boneh3ad said:No you don't. If the throat is choked, how it got that way is effectively irrelevant to what happens downstream of the choke point.
I'm aware; a hole in the wall of a pressure vessel is effectively a poor efficiency converging nozzle.You can just have a hole in the wall of a pressure vessel and attach a divergent nozzle to it to create supersonic flow.
russ_watters said:The OP didn't say the throat flow was choked in the scenario given in post #21 (or even the original scenario).
I'm aware; a hole in the wall of a pressure vessel is effectively a poor efficiency converging nozzle.
Agreed.boneh3ad said:My point is that literally anything can be used as an inefficient converging section.
Maybe, but when I pressed on what was most important to him in the original scenario, he said his specified inlet velocity, which would yield a very, very subsonic throat velocity. Given this member's history, it's entirely possible he really thinks you can get a velocity increase on both sides of the throat, even in fully subsonic flow. After all, that's what he predicted his original scenario would do.And the OP's implication was that the flow was choked since his goal was to continue accelerating the flow.
Agreed, which is why I caution against making assumptions that make sense about what he wants in the scenario. It's entirely possible (and often reality) that he is envisioning something that doesn't make sense. I often try to let go or correct and move on from little errors in the setup of a scenario, but for this user those little issues often contain landmines.The problem is that he doesn't seem to understand the physical principles involved.
How to determine the effective area for such pressure level?boneh3ad said:Now, you likely will have separation and therefore a different effective area ratio than the actual physical nozzle, but the fundamental principles remain the same.
T C said:How to determine the effective area for such pressure level?