AFAIK You cannot calculate anything from the information you have provided. I find it very odd that you have a five blade, sixteen foot long propeller fan but your tank is dimensioned in metric units. Also the longest dimension of this tank is less than the length of one of these propeller blades.

Giving you the benefit of the doubt on the fan diameter and your units soup, do you really expect us to believe that the fan is turning at 1,500 RPM's?

Ask your instructor for a different, simpler, project.

Your tank is going airborne.

After it ejects 10.35 m3 of water

The water velocity is zero; a fan moves air.

Give the guy a break. Water is composed of two gasses. Maybe this is fuzzy physics.

I think you have the correct number but for the wrong reason. As long as the water remains in the tank, the velocity of the water will be zero. The fan and tank dimensions are just red herrings. There is nothing to calculate.

If it is actually a propeller (or impeller), we need to know its theoretical pitch and efficiency in order to calculate the water velocity.

So-called "square" propellers have a pitch equal to their diameter, and their efficiencies could be around 0.65. This information can enable at least a rough estimate of water velocity. I suspect that the 16' was actually intended to be 16", but I don't know.

Lay a few yardsticks end to end, drop die at prop, use stopwatch, time die movement 1 second, take picture at 1 second, measure for velocity ft per sec....

or you could just buy one of these....

http://www.globalw.com/products/flowprobe.html

v = pnη

(Exercise for reader to match up equation terms w/ verbal terms in earlier post.)

what i understand what you meant in your statement is that the tank is rectangular and on one side there's a fan inside the tank coupled to the driver motor outside having an rpm of 1,500. And your asking what could be the velocity of the fan.

well, if my description is correct, the fan is just for agitation not for pumping water. And for the fan rpm, it is very impossible to directly couple the fan to the motor since the result would damage the motor because it needs more torque (unless for air). the fan could be indirectly driven by a belt and pulley, chain and sprocket or a gearbox (reducing gear). so for the velocity of the water after it hits the fan blade, then there are things you have to consider. The angle of the blades, the speed of the blade, etc.

but if the water is flowing to a pipe, then you can calculate V = Q/A, where Q is the volume flow rate and A for cross sectional area A=(pi x pipe dia (squared))/4. to get Q just fill any container and use stop watch to time how long it fills the container and calculate the volume of the container then you have the flow rate. then you can get the velocity of the water passing through the pipe.