3 replies to this topic

[stevenbueno]

A tank is submerged into a larger tank of gasoline which is open to the atmosphere. The submerged tank has water 30 ft of water and has a pressue of 20 psi of air. What is the velocity at the outlet of the tank if the outlet has a diameter of 0.2 in. Here is a link to the drawing. http://imgur.com/QN3TOz9

I really need the method to solve this question. It's going to be on my quiz on Monday. Please Help.

[samayaraj]

Hi,

 

You failed to provide the cross sectional area of both the tank. But, I can help you to solve this by considering the water level, air pressure over the tank and gaseoline level remains constant.

 

First calculate the head acting at the center orifice for

 

1. Pressure of air + head of water = Hw 

2. Head of gaeloine = H

 

Driving force for fluid h = Hw - h

 

Note: Hw > H

 

For velocity, v = Sqrt(2 x g x h) x Coeff of discharge of orifice.

 

Flow rate q = CSA of orifice x Velocity

 

 

Hope this is clear.

 

#Samayaraj

[breizh]

Hi ,

My advice,

Use the Bernouilli Theorem , apply it between the free surface of the submerged tank (reference 1) and the discharge point (outlet of the tank) (reference 2).  H+P/(Ro*g)+V^2/2g =cte

H1+ P1/(Ro*g)+V1^2/2g = H2 +P2/(Ro*g)+V2^2/2g + hl

 

hl :head loss through the drain.

 

Because the storage diameter is much larger than the outlet , the term V1^2/g <<<< V2^2/2g  , V1^2/2g can be cancelled .

 

Hope this helps.

 

Breizh

[Art Montemayor]

stevenbueno:

 

This Forum is not here to solve your assigned problems for you so that you can get full credit and graduate.  That is cheating - cheating against the system that is supposed to teach, guide, grade, and certify you as a future engineer.  Anyone that cheats in our profession can't be trusted with a serious and potentially hazardous project.  That is why our members should not do or help you on a examination problem.  Homework is something else.  Formal examinations are for determining if you are fit for certification.  If you are not fit after being taught and doing all the assigned homework you are supposed to do, then it is only proper that you fail the course.

 

How are you able to know what will be on your upcoming examination?  This is not the normal way of testing students.  And even when you have previously acquired the problem to be answered on the exam, you still can't resolve it???   Something is seriously wrong with your preparation, your studying, and homework.