Final_REU_Poster
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The TAMU Turbomachinery Lab conducted research on wet annular seals subjected to two-phase flow. Their existing test rig assessed the dynamic force performance of these seals but had issues with shaker movement. To address this, they designed and constructed rigidly mounted shaker frames for the X and Y directions. Vibration testing found the natural frequencies of both mounts to be over 300 Hz, outside the 10-200 Hz excitation range, resolving the shaker movement issue.
![Introduction
Since 2003, the TAMU Turbomachinery Lab has conducted research
on the effects of two phase flow on certain wet annular seals. The
research produces reliable force coefficients (stiffness and damping)
for wet annular seals and is essential in designing reliable electrical
submersible pump systems [1]. An existing test rig assesses the effect
of varying gas/liquid volume fraction on the dynamic forced
performance of a wet gas (two-phase flow) seals [2]. In the original
design, the shakers are flexibly mounted in an effort to shift the
structural natural frequency below the shaker excitation frequency
range. However, early testing showed the system to be highly damped
and revealed shaker motion due to dynamic excitations.
Rigidly Mounted Shaker Frames
Basic Principle
A box frame model is chosen in order to maximize simplicity and
fabrication efficiency while still accomplishing the design criteria. Steel
channel and ½ in. steel plating is used in part due to material available in
shop, but also meets lifelong durability. Anti-vibration matting sits between
the trunnion and frame, as well as, the frame and the table in order to
improve damping. The strut channel is in line with the intended load
direction to allow for additional structural stiffness in the event that
structure does not meet excitation frequency requirements. Guide posts
with additional holes allow for thumb screws to contact at four points on
the frame. These thumb screws can be adjusted, thus changing the angle
position of the structure. Step clamps constrain the structure once in place.
“X-Mount”
Shown above, the X-mount is constructed first in order to test the basic
model. Vibration testing determined the system’s natural frequency to be
at 312 and 328 Hz, both well above the 10-200 Hz. range. After validating
that the initial design meets our parameters, work can continue on the Y-
mount.
“Y-Mount”
Figure A shows the Y-mount’s design obstacles around the existing test
rig. The same dimensions used for the X-mount are valid for the space
provided, however, a ¼ in. is taken out of the main frame vertically in
order to make room for ¼ in. steel plating on the bottom. These plates act
as spacers around the base of the test rig’s diagonal supports.
Vibration Testing Data
Design Objective
Construct two rigid shaker mounts (X and Y directions) in order to
eliminate shaker movement emanating from a softly mounted system.
Shaker assemblies must interface with the existing test rig and have a
natural frequency above the test rig’s frequency range of 10-200 Hz.
Procedure
1. Assess space parameters and materials currently available.
2. Based on constraints, design two shaker mounts (X and Y directions) using
SolidWorks.
3. Fabricate in-house and assemble.
4. Preliminary align shaker assemblies to test rig and drill holes for table
mounting.
5. Once constrained, preform vibration testing in order to determine system’s
natural frequency; confirm natural frequency is outside excitation range.
References
[1] San Andrés, L., Liu, Q., Lu, X., 2015, “Leakage and Force Coefficients in a Wet Annular Seal:
Influence of Journal Rotation Speed,” Continuation Proposal to the TAMU Turbomachinery
Research Consortium, May.
[2] San Andrés, L., Updated 2008, “Identification of Force Coefficients in a Squeeze Film Damper
with a Mechanical Seal,” from http://rotorlab.tamu.edu/tribgroup/default.htm.
[3]San Andrés, L., Liu, Q., Lu, X., 2015, “Measurements of Leakage and Force Coefficients in a
Short Length Annular Seal Operating with a Gas in Oil Mixture,” Extended Abstract, Proceedings
of the 2015 STLE Annual Meeting & Exhibition, Dallas, TX.
[4]San Andrés, L., 2008, “TRC Squeeze Film Damper Test Rig,” from
http://rotorlab.tamu.edu/tribgroup/default.htm
`
1. “Stinger”
2. Pneumatic Shaker
3. Trunnion
4. Anti-Vibration Matting
5. Structure Frame
6. Step Clamp
7. Guide Posts
Redesign of Two Electromagnetic
Shaker Mounts: Rigid Mounts for
Vibration Testing
Final Progress Overview
Summer 2015
Mentor: Dr. Luis San Andrés
Undergraduate Presenter: Christopher Cruz
REU Program & Turbomachinery Laboratory
Texas A&M University
6
4
1
2 3
5
7
Sparger
Mixture
Pipe
Top
Plate
Support
Pipe
Transparent Seal Cartridge
Two Phase Flow Annular Seal
Basic Principle
A journal spins at high speeds within the seal cartridge (radial
clearance = 127 μm) to which an oil/air mixture is fed. Two
externally mounted shakers (100 lbf), orthogonally mounted, deliver
dynamic loads to the test rig while two eddy current sensors and load
cells record the displacement and load, respectively.
Wet Seal Test Rig
Deep sea compression systems must
work under strenuous conditions
with gas and liquid mixtures, mostly
inhomogeneous. This test rig
characterizes the leakage and
dynamic force coefficients of a short
length
annular seal operating under various
flow regimes ranging from pure gas,
to bubbly
(liquid in gas), to foamy (gas in
liquid), to pure liquid. [3]
Softly Mounted System
Two orthogonally mounted electromagnetic
shakers (X and Y directions) excite the cartridge
with periodic (single frequency) forces spanning
a wide frequency range
(10-200 Hz.). In this design
the structural natural
frequency of the system was
to be below the shaker
excitation frequency range.
Early testing showed the
system to be highly damped
and revealed shaker support
motion due to dynamic
load excitations.
Wet seal test rig [1]
Softly mounted system [4]
Vibration Testing
Once fabrication is completed and structure
is assembled and mounted to the table,
vibration testing can then begin. A thin layer
of wax attaches a 1 gram piezoelectric
accelerometer to the center of the back plate
on the shaker. Cables connect the
accelerometer to a dynamic signal analyzer.
A small rubber mallet strikes the trunnion
on the back side of the frame in line with
the mounting bolts. The dynamic signal
analyzer shows a peak amplitude of
acceleration, which corresponds to the
natural frequency of the assembly. The
dynamic signal analyzer measures four set
averages of 20 impacts. The first set of two
tests are conducted with the stinger
disconnected from the testing rig; the
second set are conducted while connected
as shown in figure below.
X-Mount Data
Y-Mount Data
A) Original Test Rig Obstacles B) Y-Mount
Oil Pan
Diagonal
Supports
Support
Base
Spacer
Plates
Peaks at 312 and 328
Hz. Gray represents test
data while stinger is
connected, blue is data
while stinger
disconnected.
Peak observed at 304
Hz. Orange represents
test data while stinger is
connected, purple
represents test data
while stinger is
disconnected.
Stinger Disconnected
Stinger Connected
X-Mount Design and Finished Product](https://image.slidesharecdn.com/a69350ff-09f0-4749-8f3e-b2cc61d4d48b-150921001324-lva1-app6892/85/Final_REU_Poster-1-320.jpg)
Final_REU_Poster
- 1. Introduction Since 2003, the TAMU Turbomachinery Lab has conducted research on the effects of two phase flow on certain wet annular seals. The research produces reliable force coefficients (stiffness and damping) for wet annular seals and is essential in designing reliable electrical submersible pump systems [1]. An existing test rig assesses the effect of varying gas/liquid volume fraction on the dynamic forced performance of a wet gas (two-phase flow) seals [2]. In the original design, the shakers are flexibly mounted in an effort to shift the structural natural frequency below the shaker excitation frequency range. However, early testing showed the system to be highly damped and revealed shaker motion due to dynamic excitations. Rigidly Mounted Shaker Frames Basic Principle A box frame model is chosen in order to maximize simplicity and fabrication efficiency while still accomplishing the design criteria. Steel channel and ½ in. steel plating is used in part due to material available in shop, but also meets lifelong durability. Anti-vibration matting sits between the trunnion and frame, as well as, the frame and the table in order to improve damping. The strut channel is in line with the intended load direction to allow for additional structural stiffness in the event that structure does not meet excitation frequency requirements. Guide posts with additional holes allow for thumb screws to contact at four points on the frame. These thumb screws can be adjusted, thus changing the angle position of the structure. Step clamps constrain the structure once in place. “X-Mount” Shown above, the X-mount is constructed first in order to test the basic model. Vibration testing determined the system’s natural frequency to be at 312 and 328 Hz, both well above the 10-200 Hz. range. After validating that the initial design meets our parameters, work can continue on the Y- mount. “Y-Mount” Figure A shows the Y-mount’s design obstacles around the existing test rig. The same dimensions used for the X-mount are valid for the space provided, however, a ¼ in. is taken out of the main frame vertically in order to make room for ¼ in. steel plating on the bottom. These plates act as spacers around the base of the test rig’s diagonal supports. Vibration Testing Data Design Objective Construct two rigid shaker mounts (X and Y directions) in order to eliminate shaker movement emanating from a softly mounted system. Shaker assemblies must interface with the existing test rig and have a natural frequency above the test rig’s frequency range of 10-200 Hz. Procedure 1. Assess space parameters and materials currently available. 2. Based on constraints, design two shaker mounts (X and Y directions) using SolidWorks. 3. Fabricate in-house and assemble. 4. Preliminary align shaker assemblies to test rig and drill holes for table mounting. 5. Once constrained, preform vibration testing in order to determine system’s natural frequency; confirm natural frequency is outside excitation range. References [1] San Andrés, L., Liu, Q., Lu, X., 2015, “Leakage and Force Coefficients in a Wet Annular Seal: Influence of Journal Rotation Speed,” Continuation Proposal to the TAMU Turbomachinery Research Consortium, May. [2] San Andrés, L., Updated 2008, “Identification of Force Coefficients in a Squeeze Film Damper with a Mechanical Seal,” from http://rotorlab.tamu.edu/tribgroup/default.htm. [3]San Andrés, L., Liu, Q., Lu, X., 2015, “Measurements of Leakage and Force Coefficients in a Short Length Annular Seal Operating with a Gas in Oil Mixture,” Extended Abstract, Proceedings of the 2015 STLE Annual Meeting & Exhibition, Dallas, TX. [4]San Andrés, L., 2008, “TRC Squeeze Film Damper Test Rig,” from http://rotorlab.tamu.edu/tribgroup/default.htm ` 1. “Stinger” 2. Pneumatic Shaker 3. Trunnion 4. Anti-Vibration Matting 5. Structure Frame 6. Step Clamp 7. Guide Posts Redesign of Two Electromagnetic Shaker Mounts: Rigid Mounts for Vibration Testing Final Progress Overview Summer 2015 Mentor: Dr. Luis San Andrés Undergraduate Presenter: Christopher Cruz REU Program & Turbomachinery Laboratory Texas A&M University 6 4 1 2 3 5 7 Sparger Mixture Pipe Top Plate Support Pipe Transparent Seal Cartridge Two Phase Flow Annular Seal Basic Principle A journal spins at high speeds within the seal cartridge (radial clearance = 127 μm) to which an oil/air mixture is fed. Two externally mounted shakers (100 lbf), orthogonally mounted, deliver dynamic loads to the test rig while two eddy current sensors and load cells record the displacement and load, respectively. Wet Seal Test Rig Deep sea compression systems must work under strenuous conditions with gas and liquid mixtures, mostly inhomogeneous. This test rig characterizes the leakage and dynamic force coefficients of a short length annular seal operating under various flow regimes ranging from pure gas, to bubbly (liquid in gas), to foamy (gas in liquid), to pure liquid. [3] Softly Mounted System Two orthogonally mounted electromagnetic shakers (X and Y directions) excite the cartridge with periodic (single frequency) forces spanning a wide frequency range (10-200 Hz.). In this design the structural natural frequency of the system was to be below the shaker excitation frequency range. Early testing showed the system to be highly damped and revealed shaker support motion due to dynamic load excitations. Wet seal test rig [1] Softly mounted system [4] Vibration Testing Once fabrication is completed and structure is assembled and mounted to the table, vibration testing can then begin. A thin layer of wax attaches a 1 gram piezoelectric accelerometer to the center of the back plate on the shaker. Cables connect the accelerometer to a dynamic signal analyzer. A small rubber mallet strikes the trunnion on the back side of the frame in line with the mounting bolts. The dynamic signal analyzer shows a peak amplitude of acceleration, which corresponds to the natural frequency of the assembly. The dynamic signal analyzer measures four set averages of 20 impacts. The first set of two tests are conducted with the stinger disconnected from the testing rig; the second set are conducted while connected as shown in figure below. X-Mount Data Y-Mount Data A) Original Test Rig Obstacles B) Y-Mount Oil Pan Diagonal Supports Support Base Spacer Plates Peaks at 312 and 328 Hz. Gray represents test data while stinger is connected, blue is data while stinger disconnected. Peak observed at 304 Hz. Orange represents test data while stinger is connected, purple represents test data while stinger is disconnected. Stinger Disconnected Stinger Connected X-Mount Design and Finished Product