Recent content by sgc7of7

Wow - heaps of info there, thanks. I'm just going to pick on one or two points at this stage though... First, I've looked at AC motors, but the mount needs to run from a portable power source. The addition of inverters etc makes things a little expensive. So onto the DC motor comment...

Ahh, I thought you were talking about modifying an old wall clock!

I can't use stepper motors because the guy I'm building this for has said "NO STEPPERS". Which is unfortunate... Clocks though, eh? Good suggestion, although as Danger said, I may need a little more torque than that required by the hour hand of a clock :) Will look into it though. I have...

Thanks for the tip Danger - I'll have a look into epicyclic gear trains. I've managed to find some good info on the Pittman website, and it seems that slowest you can run any of their servo-motors is about 500rpm, which means I still need a reduction of around 700 000:1. If I were to use a...

Hi everyone. I'm in the process of designing a telescope mount, and am now trying to figure out how to drive the thing. Ideally I would like to go with an off the shelf dc motor and gearhead setup, as this appears to be the cheapest option. My problem is, that I don't know how slowly you...

Thanks for the replies russ... Bugger, so that puts a hole in my assumption that putting a turbine in will reduce the amount of air extracted. Hang on, you mean that they are constant throughout the tunnel, but the flow rate for the case with the turbine will be lower than the case without...

Hi everyone, another question for you…. I have attached something that I’m calling a ‘flow power analysis’, which just states the power at each point of the air flow through the tunnel, and also the power into the fan and out of the turbine. There are three situations – the first with no...

Something that always confuses me is how the pressure affects the flow rate... If the pressure drops after the turbine, then does the fluid become less dense leading to a change in flow rate? Ahh, hang on...if the mass flow rate is constant, a change in pressure will lead to a change in...

Yep, a weird thing it is. I get what you have said, however, if I can't somehow show that the volume flow through the tunnel is affected by the turbine, then there is essentially no reason to increase the power to the exhaust fans. So in that respect, you kind of would be getting energy for...

Some more info that people may find useful - the flow through the tunnel is actually driven by fans that are downstream of the turbine. Sounds like an inefficient way to generate power I know, but that's the whole point - I want to be able to show why. Especially if the flow rate throught the...

Thanks for the help guys; your points have been noted. At this stage I’m not really concerned about the exact type of fan/turbine though (that will come later), I’m mainly interested in the effect that having the fan in the middle of the tunnel will have on the air flow rate through the...

Hi everyone…. I’m trying to evaluate the feasibility of putting what is essentially a wind turbine inside a horizontal exhaust shaft. I have a feeling that this would affect the volume flow rate through the shaft, but am having difficulty proving it. I have found plenty of textbook examples...