Jet pump lab
Lab L9
Prepared for:
Department of Mechanical and Aerospace
Carleton University
Prepared by:
Ephraim Inyang
101146896
ephraiminyang87@icloud.com
Lab Performed: November 4th 2021
Lab Submitted: November 22nd 2021
Table of Content
1. Abstract - (3)
2. Introduction - (3)
3. Procedure - (4)
4. Results and Discussion - (6-11)
5. Conclusion - 11
6. Appendices/References - (12-17)
Abstract
Jet pump is a device in which a primary stream of flow is injected with a certain pressure and
velocity into a tube with a larger cross-sectional area than that of the source of flow. The Jet
Pump even though less efficient as alternatives provides a way to move fluids at high pressures
with no moving parts, there is a high velocity primary stream that gets injected to pump fluids in
a tube. While mixing, a secondary stream is accelerated and has its pressure elevated, from there,
a jet pump is used to pump water from a small transparent container into a bucket. One objective
of this experiment is to compare the performance of the apparatus with a corresponding
theoretical analysis of the flow.
Introduction
With conventional pumps that have moving parts, fluids that have damaging properties (i.e.
corrosiveness, slurries with sediments, or abrasive fluids) can damage those parts. An alternative
option for pumping hazardous fluids without the risk of damage is the Jet Pump. The Jet pump is
a simple device that has no functioning parts; Although having an absence of functioning parts
may affect the efficiency of the pumping process compared to other pumps, the Jet pump is a
safe way to pump fluids that are otherwise detrimental to the machinery of conventional pumps.
The jet pump is able to function by having a high velocity fluid (Primary Stream) that is forced
into a slower moving fluid (Secondary Stream). Because the primary stream is a high velocity
fluid, the pressure of the fluid is lower than that of the secondary stream. As a result, the lower
pressure fluid creates a suction like effect that drags the higher-pressure fluid into the intake and
through the tube in which they mix and get transported to a desired area. The objective of this lab
is to analyze the behavior of the air that is pumped through the pump and to perform a theoretical
analysis of the flow using control volume and momentum principles
Procedures
In this experiment, the apparatus consisted of a primary stream with high velocity, low pressure
air at the intake of a Bell mouth connected to a mixing tube. The Bell mouth intake provided a
secondary stream at slower velocity, higher pressure air, which created suction in the tube,
mixing the different streams of air and transporting it to the desired location past the throttling
valve. Located at the exit point of the tube, the throttling valve served the purpose of changing
the cross-sectional area of the end of the tube, and resulted in a changing pressure and flow rate
throughout. Through the apparatus, there were three manometers, one tall vertical manometer
and two manometer banks. One of the manometer banks was connected to a petit-tube rake with
19 taps and an atmospheric reference tap, used in order to calculate the stagnation
pressure. The second manometer bank was connected to 17 static taps spaced sequentially along
the apparatus and an atmospheric reference tap, in order to calculate the static pressure in the
tube. A vertical manometer was connected to a pressure tap just after the pressure regulator.
For the purpose of this experiment, the valve was opened to let air flow from the primary stream
into the mixing tube. As the air travelled through the mixing tube, the manometer taps began to
read the different measurements at the desired locations. When it was observed that the
manometer readings were steady and no longer fluctuating, the values displayed were noted.
After recording the measurements on each of the manometers at eye level, and at the bottom of
the meniscus, the throttling valve was then shifted to a different location at the end of the mixing
tube, and the experiment was carried out again. Utilizing the measurements of the manometers,
essential measurements along the apparatus were recorded for calculations.
Flow Analysis
(1) Pc1= Patm – ρ*g*ΔhPC1 – Simplified Bernoulli’s Equation for calculating
pressure differences with respect to changing height of fluid.
(2) Pstatic = Patm – ρ*g*Δhstatic
(3) Vp = sqrt((2Cq (PC1 – PC2)/density of air)
(4) Q = V*A (A = π*r^2) – Volumetric flowrate, how much fluid is passing
through a unit volume per second.
(5) Vs = sqrt((2(Patm - Ps)
(6) V r = sqrt((2*(P stgn - P static))/ density of air )
Results that were calculated using formulae discussed produced the values given above. For flow
1, the primary and secondary flows were 96.78 m/s and 4.04 m/s respectively. The exit velocity
was 10.23 m/s while the secondary, primary and outward pressure were 101315.19 Pa,
101219.836 Pa and 104316.52 Pa respectively. For flow 2, the primary, secondary and outward
velocity were 97.11 m/s, 20.61 m/s and 18.55 m/s respectively. The primary. Secondary and
outward pressure were 100950.11, 101069.94 and 102354.41 respectively. All pressures in the
tube are below atmospheric which makes sense because as velocity increases, pressure
decreases.
Static Pressure Vs Inlet Values
let
Figure 1: Change in static pressure vs inlet valves
The graph above represents the change of static pressure vs the inlet values. In this graph, it
is clear that as you move along the inlet valves towards the end the pressure increases, this
increase is more notable in the closed flow scenario. The theoretical values have a higher
pressure than the actual static pressures, this could be a result of the fact that friction is
ignored in the theoretical. The slope of the graph towards the end is very low and almost
looks flat. This is because they have reached the end of the mixing region where both flows
have been mixed, therefore the mixing process was completing by the end of the tube.
Figure 2: Outlet velocity against radius
This graph demonstrates the trend of outlet velocity at different points on the radius. Even
though rictional force at the walls were neglected, it’s somewhat hard to say that the velocity is
completely uniform simply by looking at the graph. But, the trend seems to suggest that velocity
for the open valve scenario is becoming stable. However, in this case uniform flow wasn’t
satisfied and could be due to experimental or human errors which occurred during the
experiment.
Conclusion
For this experiment, we were required to apply theory previously learnt in this course. We
executed linear momentum and continuity equations among others to calculate static pressure for
different scenarios, as well as the velocities at different instances for the jet pump. Even though
the experimental data doesn’t exactly complement the theoretical data. Comparing both the
theoretical data appears more accurate for the flower with higher constant speed. Possible
sources of error for this experiment are: the equations used did not account for the frictional
forces on the wall of the tube that may have hindered the flow of the mixing air and heat loss was
not accounted for as well.
Appendix
Table 1: Throttled flow pressure values
Table 2: Open flow pressure values
Table 3: Throttled flow measured vs predicted velocity
Table 4: Open flow measured vs predicted velocity
Table 5: Throttled flow, velocity from radius
Table 6: Open flow velocity from radius
References
[1] MAAE 2300 Fluid Mechanics I