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MarkL

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Hi Guys,
I have been approached to look at vibration monitoring on a Hydro turbine, this is a Bulb type Kaplan turbine, there are three points which we have identified possibly taking signal;s from but the issue I have is this, we can get a waterproof accelerometer, but I have concerns about noise, as in the turbine Oem suggest the three points are on the outer casing of the turbine as close to the bearings as physics will allow us, but the sensors will be submerged in a 3metre chamber that has 12 m3  per second  flowing through it! I am concerned will this turbulence have an effect on the accelerometers readings and create loads of spurious background noise?

Have any of you come across a similar application, see image attached of a similar type unit. 

1st Image the gearbox which has the propellor mounted on the left of the image shown, the vertical flange has the generator 500kw with rolling element bearings in it.
[108031-3587747] 

That gearbox is inside the green shroud in the image shown below Propellor is at the downstream end of the shroud, and you can see the generator above it(Blue)

[maxresdefault]

 My biggest concern is noise from the turbulent flow around the sensors when we have them bolted to the gearbox casing.  

Your thoughts and input appreciated.
OLi

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I have naturally only experience from MC velocity probes... We have a lot of these various "submarine" devices in some cases monitored since 30-40 years or more. I have seen no problems with flow noise (unless flow is obstructed so it cavitate) . Just cover the transducer with the black guck they use to cover these things and all is fine, sometime a piece of timber or ice may hit and destroy a sensor but it is quite rare. Have fun. Olov
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MarkL

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Reply with quote  #3 
Oli, 
Your use of the work Guck made me smile...where I come from its a slang for crap.. but I guess you mean the same thing in Sweden!

Thats a great Idea though, I will have a go and see how that works out, sometimes the simplest approaches are the best.
OLi

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Well our languages have a common root and things like that may have had the same meaning the last couple of thousand years, at least in water connected items.....[wink] You know who is claimed to founded Dublin? I think you can look at bearing problems as usual, including gbx's in hydro do add some maintenance so watch the trending...... It makes them closer to wind turbines. Olov
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Good Vibrations since early 1950's, first patented vibrometer 1956 in the US.
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RustyCas

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Reply with quote  #5 
In the field I have found sensors are pretty much immune to background noise. I like OLi's idea about coating them over with some sort of tar or rubber based goop that is somewhat pliable (stays somewhat soft), but very tenacious (sticks tight). This would inhibit transmission of any "noise" in the flow stream.
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