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Thanks everyone. With all of the mentioned things in mind I'll go over the standard once more. Maybe also some of the answers I'm looking for are in ISO 5459, I'll give that a second read too.

pmarc, Indeed there would be an infinite number of solutions (assuming the former practice of the leader lines is somehow insufficient). Then I ask, how does B specify the orientation of the tolerance zones? The one might be at 0 degrees and the other at 90. Or the one might be at 90 degrees and...

3DDave, Ah yes, the orientation of the measurement, I see that now. Do you agree then that in the first case B is not used for the orientation of the tolerance zones wrt the work piece? This is what I was trying to figure out: How does B constrain the tolerance zone? Answer: It doesn't. Thanks.

Thanks 3DDave, the figure is indeed from section 8 and reading it doesn't clarify how it works for me. My confusion lies in how the relationship is implied. I will expand a bit. I understand that the parallelism symbol relates the tolerance zone orientation to datum A. I think the parallelism...

By second, do you mean b) 3D? Then the first one being a) 2D, I don't mind machine readable. - Is it correct? (It's straight from the standard) - How does it constrain the tolerance zone further? Edit: It being datum B. - Where is this rule printed in ISO 1101:2012? - Given that leader lines...

Hi, I'm trying to understand how previous editions of ISO 1101 specified the orientation of tolerance zones in the 2D case. Datum A indicates the center of the larger hole and both tolerance zones are parallel to it. Is B now the orientation plane? How does it constrain the tolerance zone...

Hello, Axial flow machines (compressors, turbines, fans) may be designed for a number of vortex distributions such as free vortex and forced vortex. In "Fluid mechanics and thermodynamics of turbomachinery" by S. L. Dixon another distribution is suggested that results from a constant specific...

Hi, I'm trying to scale up an existing air expansion turbine using similatiry laws, specifically getting the same non-dimension mass flow parameter for the scaled up turbine. I know various conditions for the existing turbine and the power requirement for the scaled up turbine. 01 = stagnation...

Pre-swirl will shift surge to the left. Head rise to surge will increase at the expense of maximum flow.

Btw, while centrifugal gas compressors are typically mechanically tested at vacuum conditions, I'll have to agree with jbattershell because things like load and density sometimes have profound effects of the rotordynamics.

The purpose of a mech running test is not to test the mechanical losses. It would be a meaningless number since "vacuum" will actually be ~0.1 bar causing the compressor to do a few (10-100) kW of gas power. Varying the oil temperature is done mainly to demonstrate rotordynamic stability over a...

Hello, I have the "Fan Handbook" by Frank P. Bleier. This book is ok as a primer but somewhat limited for detailed selection, let alone design. If you have any book recommendations covering things like -fan geometry beyond the outer diameter (number of blades, angle etc) -the resulting...

Thanks TERIO. That looks very usefull to my problem.

> that's called pulling something out of your butt Absolutely. > you should be able develop a more meaningful stiffness > and stress distribution with good akward modeling and > proper interpretation of the results. I was hoping to steer clear of FEA for one because I currently don't have...

TERIO, that's what I mean. Your sketch illustrates it nicely.

Thanks for your input. > Why do you think that calculating the stiffness of the > middle segment as K_2=G*J_2/L_2 in inappropriate? While that formula works for a shaft with one radius I think I read somewhere that a shaft segment has less stiffness than its nominal value if neighboring...

But how can you find an appropriate stiffness for the middle segment? I was thinking something along these lines: r1 300 l1 300 r2 900 l2 300 r2_effective = r1 + l2/2 = 450 mm and use r2_effective to calculate the stiffness of the middle segment. Would that do? Thanks.

Hello, I'm writing some code to do rotor dynamic analysis(compressor trains). The rotor is read from a file and stiffness is calculated as follows: k = G*I/(l/1000) # /1000 because input is in mm But given the following rotor (all mm) dia len 300 300 900 300 400 300 the calculated stiffness of...

katmar, Thanks for your input. I thought 5% to be a bit much as well. Perhaps there's an error in my program, I'll need to go through it again.

No, just structured. Though the chemical part of natural gas compression is not my strongest point. We have Design2 but it doesn't integrate well into some of the in-house tools. I'm looking for a reasonable alternative to speed tasks such as orifice sizing and generally get a better...