Recent content by kandelabr

I stick to Gulich's Centrifugal pumps. The recipe there is really just a recipe. A few examples: angle of incidence at inlet should be slightly larger than the flow angle. how exactly, is up to you, but somewhere between 1-5 degrees. there are two cones in meridian cross-section, one at the...

i managed to whip something up. the procedure is fairly straightforward: set inlet and outlet diameters. the former can be calculated directly, the latter can be corrected afterwards. calculate inlet and outlet velocities based on flow and head requirements. calculate acceleration components in...

Didn't have those in mind. I'm not an expert on Pelton wheels but the design of those looks more straightforward to me. That's the sort of keywords I've been lookng for :) I'll have a look. Thanks! That's why pumps usually have lower efficiencies than turbines. I'm obviously unlucky to be in...

I'm not trying to avoid CFD. I just wish to update the current (decades old) design recipes to get rid of some empirical equations. The airfoil approach can be used in propellers and axial/diagonal turbines with high flow and low head. High head, low flow are centrifugal machines and are...

That's a good point. Thinking about it now, there are two different extremes: The shortest path through impeller/turbine causes high accelerations/velocities and causes all kinds of turbulent losses. Blades are very short and the output angle is large. The longest path is the most gentle but...

Currently design of turbomachinery (impellers/turbines) is more a form of art than an engineering process. One has to guess a bunch of parameters and check if they are right in much later stages of design. I was thinking about designing the other way: we know the initial and the final velocity...

I actually tried that before - I chose random points and solved the system numerically with numpy, but the problem is that measurements have some noise and different points give different results. I even chose multiple sets of random selections of points and averaged the results, but it doesn't...

looks interesting, i'll check it out. thanks

what do you mean with "don't need an algorithm"? I'm solving overdetermined system of equations using least squares. am i missing something?

Whoa, sorry for late reply. Let me answer all of you at once. I have tried, and voila, it's much better. I have also found out that I can fix one parameter and only fit the other. That makes everything very simple. This is a calibration of a somewhat simplified capacitive displacement sensor...

I have a set of data points that I must fit to an inverse function like this: y(x) = a/(x+b) + c My problem is that least-squares fitting using this equation is extremely unstable and heavily dependent on initial guess. No matter how accurate parameters I start with, the algorithm often goes...

that's a good idea. let me try :) thanks, kandelabr

Hello, i've just got a home NAS and it has an option to use it as a FTP server, but if i want to use it as one, i need to set its ip to be the "DMZ computer" in router's settings. i know it's a security risk for computers, but is it also for a NAS? i can set the precise username and...

yeah, i thought this would be the explanation, and i neglected that bode plot is steady-state only. thanks!

OK, so i forgot G >> 20*log(G), and so the diagram is wrong, but still, the question remains the same - see this diagram: http://en.wikipedia.org/wiki/File:Bode_High-Pass.PNG