Inducted cool air 12v electric turbine questions

A cool air turbine with a tubular duct that runs from its exhaust to its intake. 

Would the air speed in the duct be faster due to vacuum force rather than being open ended?

Would the turning force on another inline turbine introduced into the duct system be greater or less?

Would the air speed decrease after the added inline turbine to the duct system?

This is not homework help its things that I have been thinking about due to a hobby project I been woking on but have no way of measuring air speed or turning force. 

I think it would increase airspeed and turning force on second turbine. I also think once the second turbine has spooled up too speed the air speed after second turbine wouldn't be decreased. I am thinking pushing force and vacuum force in the duct system would over come loss of air speed due to turning force.

Btw I dont get paid to think. The above is the reason why so.

 If you can honestly help me anwser my questions it would be helpful. Do not bother replying if you lack tact in your reply.

Edited November 25, 20178 yr by Schizo@play
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