Diesel Electric?

[cabbage]

Tim. OK how would you like to try one at 67Cu Ft min ?

http://www.ebay.co.uk/itm/New-Case-Fan-12V-DC-50CFM-PC-CPU-Computer-Cooling-Sleeve-Bearing-3-Pin-80mm-25mm-/170889333366?pt=UK_Computing_Case_Fans&hash=item27c9cc4a76

This is the XP1700 heatsink (And cheaper too!)

http://www.ebay.co.uk/itm/AMD-XP-Aluminium-CPU-Cooler-Cooling-Heatsink-Fan-702430-/370529692567?pt=UK_Computing_Case_Fans&hash=item56454a6b97

Andrew. Yes the system is under steady state (ie with the bar and weight fitted to the output shaft on top of a work mate). The figure you have of 4.2:1 is the shaft rotation reduction and yes there is a separate cooling system for the water that is the working fluid using P2  CPU cooler. The original used Diesel fuel! How the torque varies under load I have no way of measuring as "Kitchen Sink Engineering" lacks the equipment. So all I can tell you is that at 4,000 RPM into the T/C I get 0.6Nm out of it. This feeds the gearbox which has a ratio of 90:1

Has anyone anymore questions before I go to bed???

regards

ralph

[Peaky 556]

Thanks for tip Ralph, I've ordered one at that price!  It's slow boat from China tho, so will report when it arrives in March!
Rgds, Tim

[andrewfoster]

. ..... "Kitchen Sink Engineering" lacks the equipment. So all I can tell you is that at 4,000 RPM into the T/C I get 0.6Nm out of it. This feeds the gearbox which has a ratio of 90:1

Has anyone anymore questions before I go to bed???

regards

ralph

OK - we're talking the same language, then! I also have impeccable kitchen sink engineering credentials, as well as a little of the other kind - just ask my long suffering wife.  It's a fascinating kind of project you've got going.

Andrew

[Peaky 556]

Tim. OK how would you like to try one at 67Cu Ft min ?

http://www.ebay.co.uk/itm/New-Case-Fan-12V-DC-50CFM-PC-CPU-Computer-Cooling-Sleeve-Bearing-3-Pin-80mm-25mm-/170889333366?pt=UK_Computing_Case_Fans&hash=item27c9cc4a76

This is the XP1700 heatsink (And cheaper too!)

My (claimed) 67 CFM cooling fan has arrived from China.  [It came by airmail, so how do they market this for £1.20 inc postage and make any profit?]  Short of testing in just a very subjective 'draft in the face' comparison with other fans I have, any ideas from anyone on how to demonstrate some comarative advantage?
Cheers, Tim

[cabbage]

Well the method used by my son for his fans does seem applicable here... A 10cm square of cornflakes packet hinged at the top with parcel tape on a coat hanger wire "football goal post frame". The distance needed to blow the square an inch off vertical is the measure used by him.

regards

ralph

[Peaky 556]

Well the Cabbage Mk2 air flow meter I constructed last night (see pic, modified with ballpoint pen as weight) shows that the new super-cheapo 67 CFM fan blows no harder than the 31 CFM fan I already have!  In fact there might be subtly less performance, and the package is bigger too at 25 mm thick cf. 15 mm.  Oh well, you get what you pay for...
Regards, Tim

[John Candy]

Do you think some of the airflow may be lost "radially" and not reaching the "gauge".

How about blowing it through a tube?

Centre of a fax machine paper roll/kitchen towel roll, etc.

Toilet roll centre may be too short.

John.

[John Candy]

Another suggestion (came to me while brushing my teeth)!

Why not mount the fan in a length of plastic waste pipe/drain pipe, then cut squares of card sufficiently large to cover the end.

Get some small weights (lead shot would be a good source) then glue differing weights to each card, then see how much "lift" each fan can generate in "vacuum cleaner" mode.

Perhaps not the ultimate test but could give a better (calibrated) result then the "flap" method.

John.

[454]

1) Make a duct.
2) Mount the fan.
3) In the duct make a hole for a tube to be normal to the flow.
4) make a tube like a hockey stick to sit in the flow, pointing into and inline with the flow.
5) Connect the "tappings"up to a bent glass tube filled with water.

Make a pair one for upstream of the fan and one for downstream of the fan if you are that keen.

The tapping in the wall normal to the flow measures the static pressure.
The tapping in the hockey stick tube pointing into the flow is the total pressure.

The differential separation distance of the water levels in the "water manometer" tube will be a guide to the flow.

6) You now have the basis for a mass flow meter. However, you will also need a thermometer
to measure the absolute temperature.

7) Find the barometric pressure of the day. The colder the air the greater the mass flow.

Total pressure minus static pressure is called "dynamic head".

Do a bit of a calculation & hey presto result mass flow.

Thats how it was done in the aeronautical industry, when I was a lad.

Don't ask me any embarrasing questions as I am now retired!

Cheers
Dave
454

[Peaky 556]

Hmmm....
I think I have a pitot tube liberated from the scrap heap!  Definitely not a bent bit of glass tube though.  I'll have a think if I really want to quantify the airflow, but in reality I just want to know which fan blows more...   I may next build the 'Candy-pipe' flow meter instead!
Regards, Tim