Physics

posted by .

Lubricating oil, with a relative density of 0.79, flows around a 90¨¬ bend. The pipe diameter is 0.45m, and the oil has a pressure head of 7m and the flow is 1.7m3/s. Find the force exerted by the oil on the bend.

Oil density = 0.79 X 103
Volumetric mass flow rate = 1.7 m3/s
Pipe diameter = 0.45 m
Oil mass flow=density*Vol/sec
Mass flow=0.79X10^3*1.7
Mass flow=1343kg/sec

Oil velocity in the pipe:
Vel.*pir^2=1.7m^3/sec
vel.=1.7/pi*(0.45/2)^2
vel of oil=10.69m/s

Force(F1) on the bend due to oil flow:
F1=Oil mass flow*Oil velocity
F1=1343*10.69
F1=14356kgm/s^2 or 14.356kN

Force(F2) due to oil pressure:
p=7m*0.79X10^3kg/m^3*9.81m/s^2
p=54249kg/ms^2
F2=pA
F2=54249kg/ms^2*(0.7854X0.45^2)
F2=8627kgm/s^2 or 8.627kN

Total Force(Ft) acting on elbow:
Ft=F1+F2
Ft=14.3456kN+8.627kN
Ft=22.983kN (ans.)

Thanks for taking a look.

• Physics -

It was not clear to me if the "pressure head" of the fluid was in meters of mercury, water or the oil. Your assumption that it the fluid flowing (oil) makes sense.

I agree with your mass flow and velocity numbers. There are two components to the reaction force on the 90 degree bend. To change the direction of the momentum flow by 90 degrees, you need a force equal to the magnitude of the momentum change vector, which is sqrt2 times the flow scalar momentum. The force acts at 45 degrees to the two flow directions.

As you have noted, there may be an additional force due to the loss of pressure at the turn. The loss will be approximately equal to the pressure head for a 90 degree turn. I do not believe this is an exact rule. It seems to me that this should be treated as a vector also, since the two pressure forces before and after the bend act in perpendicular directions.

Similar Questions

1. Fluids in motion

Lubricating oil, with a relative density of 0.79, flows around a 90º bend. The pipe diameter is 0.45m, and the oil has a pressure head of 7m and the flow is 1.7m3/s. Find the force exerted by the oil on the bend.
2. physics

Lubricating oil, with a relative density of 0.79, flows around a 90¨¬ bend. The pipe diameter is 0.45m, and the oil has a pressure head of 7m and the flow is 1.7m3/s. Find the force exerted by the oil on the bend. Oil density = 0.79 …
3. Physics

Lubricating oil, with a relative density of 0.79, flows around a 90¨¬ bend. The pipe diameter is 0.45m, and the oil has a pressure head of 7m and the flow is 1.7m3/s. Find the force exerted by the oil on the bend. Oil density = 0.79 …
4. physics

A horizontal pipe of diameter 0.845 m has a smooth constriction to a section of diameter 0.507 m. The density of oil flowing in the pipe is 821 kg/m3 . If the pressure in the pipe is 8350 N/m2 and in the constricted section is 6262.5 …
5. physics

A horizontal pipe carries oil whose coefficient of viscosity is 0.00010 ns/ m^{2}}. The diameter of the pipe is 5.5 cm, and its length is 60 m. What pressure difference is required between the ends of this pipe if the oil is to flow …
6. Physics

A bucket is filled with a combination of water (density 1,000 kg/m3) and oil (density 700 kg/m3). These fluids do not mix. (The oil will float on top of the water.) If the layer of oil is 63 cm tall, what is the pressure at the interface …
7. PHYSICS!!!

A straight horizontal pipe with a diameter of 1.0 cm and a length of 46 m carries oil with a coefficient of viscosity of 0.11 N · s/m2. At the output of the pipe, the flow rate is 8.4 10-5 m3/s and the pressure is 1.0 atmosphere. …
8. physics

An oil gusher shoots crude oil 29.0 m into the air through a 0.100 m diameter pipe. Neglecting air resistance but not the resistance of the pipe, and assuming laminar flow, calculate the pressure at the entrance of the 55.0 m long …
9. physics

Two equally long 12-cm diameter pipelines have the same pressure difference between ends. One carries a ‘Type A’ oil (𝜂 = 0.091 Pa s) and the other a ‘Type B’ oil (𝜂 = 0.064 Pa s). If ‘Type …
10. Physics

1. A cylindrical disk of wood weighing 45.0N and having a diameter of 30.0 cm floats on a cylinder of oil of density 0.850 g/cm3. The cylinder of oil is 75.0 cm deep and has the same diameter of the wood. (a) What is the gauge pressure …

More Similar Questions