Stack design_STS-1
Stack design_STS-1
(OP)
Hello everyone,
For stack, designed as per STS-1, i am in a situation that critical velocity is lower than design velocity.
So far i know by introducing helical strakes or other attachments, critical velocity can be increased.
But my question is how to evaluate critical velocity after introducing strakes.
Please provide your opinion/ guidance on same.
Izzy
For stack, designed as per STS-1, i am in a situation that critical velocity is lower than design velocity.
So far i know by introducing helical strakes or other attachments, critical velocity can be increased.
But my question is how to evaluate critical velocity after introducing strakes.
Please provide your opinion/ guidance on same.
Izzy





RE: Stack design_STS-1
In Dennis Moss, Chapter 6: special designs, it says that Vortex shedding can be eliminated by introducing helical strakes upto top 1/3 portion of stack.
As per above, does it mean that by introducing strakes there is no need to check for vortex shedding.
If so than how to validate it on paper.
Izzy
RE: Stack design_STS-1
You have asked the same question twice - this is not the done thing.
As regards you question. Introducing strakes does not negate the nedd to check for resonance. How do you know how many - their width- the spacing of these strakes? I think you should employ a qualified stack design engineer.
RE: Stack design_STS-1
RE: Stack design_STS-1
To investigate further for the cause of failure, I checked ovalling frequency.
But I found that ovalling frequency is more than natural frequency of vessel even with less thickness of shell components. See the attachment.
Still, I am not able to conclude the reason for failure.
I request you to explain the same if possible.
Thanks.
RE: Stack design_STS-1
Exactly, i do agree with you.
But i am not able to understand the reason for statement in Dennis Moss (See the attachment- Extract from Dennis Moss).
RE: Stack design_STS-1
Have you contacted the people who developed the computer program (COADE) that you are using ?
What did they have to say ?
MJCronin
Sr. Process Engineer