Turbomachinery velocity triangle problem

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The discussion revolves around determining the outlet absolute velocity direction of air flowing across a rotor, given that the fluid exerts no torque on the rotor. The user calculates the tangential velocity at the outlet using Euler's Torque equation, concluding that the device is likely a pump since the fluid does not perform work on the rotor. There is uncertainty about the direction of the outlet velocity, which needs to be confirmed using velocity triangles. A suggestion is made to apply the Pythagorean theorem to complete the velocity triangle and find the angle. The conversation emphasizes the importance of understanding the relationship between velocity and torque in turbomachinery analysis.
MacLaddy
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Homework Statement



Air (assumed incompressible) flows across the rotor shown in the figure such that the magnitude of the absolute velocity increases from 15 m/s to 25 m/s. Measurements indicate that the absolute velocity at the inlet is in the direction shown. Determine the direction of the absolute velocity at the outlet if the fluid puts no torque on the rotor. Is the rotation CW or CCW? Is this device a pump or a turbine?

Homework Equations



Euler's Torque equation

T=\dot{m}(r_2V_{\theta2}-r_1V_{\theta1})

The Attempt at a Solution


[/B]
As torque = 0

T=\dot{m}(r_2V_{\theta2}-r_1V_{\theta1})=0

(r_2V_{\theta2})=(r_1V_{\theta1})

V_{\theta2}=V_{\theta1}*\frac{r_1}{r_2}=15\sin{60}*\frac{1.9}{1.2}=20.57 m/s

No idea where to take it from here. I can't tell from the problem statement if the direction of V_2 is as indicated.

If there is no torque, as indicated, then I would assume that this must be a pump--as the fluid isn't doing any work on the rotor. However, I believe I need to prove this with velocity triangles and the like.

Any help would be appreciated.
Mac
 
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It looks like you found the velocity in the same direction as V1. The problem gives you the full velocity. You can complete the triangle using the Pythagorean thm, and find the angle from that.
 

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