Can i get valuable information from a wind tunnel with almost nothing straightening the current?

All i have straightening the current are 8 cups, wide end facing the fan. The end is cut out to let the air flow and all the cups are pointed slightly inward to the stand holding my design.

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Get a packet of drinking straws, open both ends, and blow the flow through them, to get a close to laminar flow as you can manage.

Steve
rickharris7 years ago
To answer you question you could measure and calculate the drag factor - Or by putting the model on a spring scale measure the relative drag between different design changes - To get meaningful air flow indications (the bit that do with smoke trails or lots of bits of wool stuck to the model to show how smooth or not the air flow is you do need a smooth flow - For that Steve is right on the button. It's not that difficult - we built one at school fairly quickly.
What kind of cross section was your tunnel Rick ?

Steve
Square (easy to manufacture and use) about 2000x 500 x 500 and powered from a large floor fan we happened to have - we used the straws to linearise the flow although we only did drag calculations in it.

It seemed to work considering that the gap between making models and then recreating the best model full sized was huge.

Thinking about it further, and in answer to this question ) (Campaign signs), over here in the UK, they are often made of corrugated plastic. You could cut and stack strips of them, and make flow straighteners.

Steve
kelseymh7 years ago
What Steve said (he should get Best Answer). Your design will give fairly turbulent flow, and you won't get much in the way of good data. Take a look at the replies to this same (almost) question. Doing an I'ble search for "wind tunnel" should help, also.