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Estimation of Dynamic Force Coefficients from a Wet (Foamy) Annular Seal

Progress Year 1 May 2013

33rd Turbomachinery Research Consortium Meeting

Gary Bradley M.S. Student

TRC Project 32513/1519NS

Luis San Andrés Mast-Childs Professor

$ 44,984

Bubbly mixture annular seals

As oil fields deplete compressors work off-design with liquid in gas mixtures, mostly inhomogeneous.

Similarly, oil compression station pumps operate with gas in liquid mixtures.

The flow condition affects compressor or pump overall efficiency and reliability.

Little is known about seals operating under 2-phase conditions, except that the mixture affects seal leakage and system reliability.

JustificationSeals operate with either liquids or gases, but not both…..

San Andrés, L., 2012, “Rotordynamic Force Coefficients of Bubbly Mixture Annular Pressure Seals, ”ASME J. Eng. Gas Turbines Power, vol. 134 (Feb), 022503

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Proposed Work (Year 1)

• Prepare test rig for measurements (50%)• Seal test rig (100%)• Center journal/bearing, calibrate instrumentation, install

shakers (100%)• Prepare motor to run up to 6000 rpm (50%)• Prepare oil supply/return system (50%)

• Make air/oil mixing fixture that will produce consistent wet (foamy) mixtures (50%)• Fabricate mixing device• Prepare mixing device for supply pressure up to 100 psig • Construct de-aeration device

• Perform initial dynamic load measurements and devise a procedure to extract the characteristic force coefficients (0%)

$ 44,984

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Revamped vertical SFD rig

Air Inlet

Oil Inlet(ISO VG 10)

Test seal section

Valves

ValvesSparger (mixing) element

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Test Rig PreparationSeal section is currently assembled and air tight with no leaks

Oil supply/return pumps all currently in working order

Air supply in working order (awaiting air flow meter calibration)

Mixing (sparger) element currently producing mixtures (homogeneity of mixture to be checked)

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Test Seal Section

Top Plate 1

Top Plate 2

Plexiglas bearing

Journal (inside)

Bottom Plate

Gasket

O-ring

O-ring

Seal dimensionsClearance, c=5 milLength, L=1.0 inchDiameter, D=5.0 inch

Difficulties•Too many sealing surfaces•Sensor placement not ideal

•Plexiglas threads easily stripped and cracked

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New Design Test Seal Cartridge

Top Plate

Bearing (steel)

Journal

Rotor

O-ring

Seal dimensionsClearance, c=5-15 mil

Length, L=0.5-1.75 inchDiameter, D=5.0 inch

Advantages•Fewer sealing surfaces

•Sensor placement as needed•Made of steel (no cracking/stripping

of material)

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Progress through Year 1August 2012 – January 2013•Ph.D. student funded

• Worked to seal test rig – Did not finish• Quit in January of 2013

January 2013 – April 2013•Project went without progress (no student)

April 2013 – Present•Undergraduate student worker w/ supervision of grad student

• Sealed test rig (air tight, no leaks)• Centered test rig• Designed simpler test seal section (for future manufacture)• Working to separate air from foamy mixture

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Outlook for Year 2June 2013 – August 2013•Finish preparing test rig•Estimation of mixture properties (air/oil %, density, viscosity, etc.)•Find new graduate student to take over project

August 2013 – December 2013•Prepare data acquisition system•Make initial measurements

January 2014 – May 2014•Identification of seal force coefficients for a number of operating conditions•Write comprehensive TRC report and proposal for future work

No more funding is sought for 2013-14.