Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
  • F01D—NON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES
  • F01D11/00—Preventing or minimising internal leakage of working-fluid, e.g. between stages
  • F01D11/08—Preventing or minimising internal leakage of working-fluid, e.g. between stages for sealing space between rotor blade tips and stator
  • F01D11/12—Preventing or minimising internal leakage of working-fluid, e.g. between stages for sealing space between rotor blade tips and stator using a rubstrip, e.g. erodible. deformable or resiliently-biased part
  • F01D11/122—Preventing or minimising internal leakage of working-fluid, e.g. between stages for sealing space between rotor blade tips and stator using a rubstrip, e.g. erodible. deformable or resiliently-biased part with erodable or abradable material
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
  • F04D—NON-POSITIVE-DISPLACEMENT PUMPS
  • F04D29/00—Details, component parts, or accessories
  • F04D29/08—Sealings
  • F04D29/16—Sealings between pressure and suction sides
  • F04D29/161—Sealings between pressure and suction sides especially adapted for elastic fluid pumps
  • F04D29/164—Sealings between pressure and suction sides especially adapted for elastic fluid pumps of an axial flow wheel
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
  • F05D—INDEXING SCHEME FOR ASPECTS RELATING TO NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES, GAS-TURBINES OR JET-PROPULSION PLANTS
  • F05D2300/00—Materials; Properties thereof
  • F05D2300/40—Organic materials
  • F05D2300/43—Synthetic polymers, e.g. plastics; Rubber
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
  • F05D—INDEXING SCHEME FOR ASPECTS RELATING TO NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES, GAS-TURBINES OR JET-PROPULSION PLANTS
  • F05D2300/00—Materials; Properties thereof
  • F05D2300/60—Properties or characteristics given to material by treatment or manufacturing
  • F05D2300/603—Composites; e.g. fibre-reinforced
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
  • F05D—INDEXING SCHEME FOR ASPECTS RELATING TO NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES, GAS-TURBINES OR JET-PROPULSION PLANTS
  • F05D2300/00—Materials; Properties thereof
  • F05D2300/70—Treatment or modification of materials
  • F05D2300/702—Reinforcement

Definitions

• This invention relates to resilient composite abradable materials, and particularly to abradable materials for use in the compressor sections of gas turbine engines, and particularly in the low compressor section of such engines.
• Modern large gas turbine engines have axial flow compressors which include multiple circular airfoil arrays mounted at the periphery of rotatable disks. Adjacent each set of moving compressor airfoils is an array of stationary airfoils. The efficiency of such a compressor is strongly affected by air which leaks around the ends of the moving airfoils. The typical approach to minimize such leakage is to provide an abradable air seal with which the compressor airfoil outer ends interact to minimize leakage.
• U.S. patent 3,575,427 describes the abradable seal materials similar to those which are currently in use in engines produced by the present applicant.
• the seal material of U.S. patent 3,575,427 comprises a resilient matrix material containing a dispersion of friable hollow glass microspheres.
• an object of this invention to describe an abradable material for use in modern high temperature gas turbine engines. It is another objective of the invention to describe an abradable material which whose constituents will not subsequently adhere to combustor and turbine components. It is yet another object of the invention to describe a compressor of abradable material which exhibits higher erosion resistance over temperatures ranging from room temperature to 400° F (204°C) than the currently used material and is usable in temperatures up to 450° F (232°C), and exhibits desirable abradability characteristics.
• the invention comprises a high temperature resilient material comprising a high temperature capable silicone polymeric material which contains a dispersion of high temperature capable organic particles.
• the particles are preferably selected from a material which is stable to at least 400° F (204°C).
• the particles are preferably present in the seal in an amount of about 10 wt %.
• the silicone polymeric matrix is selected so as to be thermally stable at temperatures in excess of 300° F (149°C) and preferably in excess of 450° F (232°C). Most preferably the silicone polymeric matrix can withstand short temperature spikes of up to 550° F (288°C) without undue deterioration.
• the invention provides an abradable material which comprises: from about 5 to about 20 weight percent of Abradable Organic Filler Particles (AOFP) in an Abradable Silicone Polymer Matrix (ASPM).
• AOFP Abradable Organic Filler Particles
• APM Abradable Silicone Polymer Matrix
• This invention in various embodiments comprises a matrix containing a particle or low aspect ratio ( ⁇ 10:1) fiber dispersion.
• abradable silicone polymer matrix or ASPM is used herein as a defined term for a material that is a resilient one or two part silicone polymer preferably catalyzed by a precious metal selected from the group consisting of Ru, Rh, Pd, Os, Ir, Pt and mixtures thereof, which is thermally stable at at least 300° F (149°C).
• the cured ASPM material preferably has a room temperature tensile strength of greater than 400 PSI (2.76 Nmm -2 ), an elongation to failure of greater than 100%, and a Shore A (Durometer) hardness of from 15-75, more preferably 15-50.
• ASPM material is a dimethyl or methyl phenyl silicone.
• the ASPM material contains a transition metal oxide selected from the group consisting of oxides of V, Cr, Ce, Mn, Fe, Co, Ni, or other transition metal and mixtures thereof with iron oxide being particularly preferred.
• the transition metal oxide acts as a thermal or thermal oxidative stabilizer.
• the ASPM material is produced from a mixture of a vinyl terminated polymer having a molecular weight of 1,000 g/mol to 1,000,000 g/mol; a silane crosslinker having a molecular weight of 300 g/mol to 10,000 g/mol and a precious metal catalyst, most preferably Pt.
• the ASPM may also contain a reinforcing file such as fumed silica.
• the room temperature tensile strength of the cured ASPM material exceeds 1,000 PSI (6.9 Nmm -2 ).
• the room temperature elongation to failure of the cured ASPM material exceeds 800%.
• the Shore A Durometer hardness of the cured ASPM material is from about 15 to about 40.
• the cured ASPM material is oxidation resistant, exhibiting less than 2% weight loss after 100 hours (using a 1" x 1" x 1 ⁇ 4" (25.4 mm x 25.4 mm x 6.3 mm) sample) at 300° F (149°C), and most preferably at 400° F (204°C) exposure in air.
• the cured ASPM material is thermally stable, losing less than 20% of its tensile strength after 100 hours at 300° F (149°C), and preferably 400° F (204°C).
• abradable organic filler particles or AOFP is used herein as a defined term meaning a material that is hard, organic, and that retains useful properties at 300° F (149°C).
• the AOFP material must contain less than about 2% S to ensure proper curing of the ASPM material.
• the AOFP material must have a glass transition temperature which exceeds 300° F (149°C) and a room temperature impact strength in excess of .5 ft-lb/in to reduce the likelihood of particle breakage during abrading conditions in engine operation.
• the AOFP material retains useful mechanical properties at temperatures in excess of 500° F (260°C).
• the AOFP material contains less than about 2 wt% F so that the products of AOFP material combustion are not corrosive to gas turbine materials.
• the AOFP material contains less than about 1 wt% S and less than about 1 wt% F.
• the AOFP material produces only gaseous combustion products when combusted in a gas turbine engine at temperatures in excess of 2,000° F (1093°C) generally oxidizing conditions.
• Non combustable fillers preferably have a particle size of less than 1 mil (0.025 mm).
• the AOFP material has a glass transition temperature exceeds about 400° F (204°C).
• the AOFP material has a Deflection Temperature, measured according to ASTM D 648, at 1.8 MPa, which exceeds about 400° F (204°C), and preferably exceeds 500° F (260°C)
• the AOFP material has a room temperature tensile strength which exceeds 10 ksi (68.9 Nmm -2 ).
• the AOFP material has a room temperature elongation to failure which exceeds 1%.
• the AOFP material has a room temperature Izod impact strength which exceeds 1.0 ft-lb/in.
• the particles which are added to the matrix material serve to slightly weaken the matrix material, and make it more abradable. It is well within the ability of one skilled in the art to select the proper amount of particulate material for a matrix material having particular qualities to achieve the desired degree of abradability. We prefer to use from about 5 to about 20 weight percent particles.
• the particles are preferably selected from the group consisting of polyamides, polyimides, polyamide-imides, as well as other thermoplastic and thermoset materials which are stable in the gas turbine compressor operating environment.
• Torlon 4000 which is available from the BP Amoco Company of Chicago, Illinois.
• Torlon 4000 which is available from the BP Amoco Company of Chicago, Illinois.
• 90% of particles have a size which is less than about 150 micrometers and that 90% of the particles fall in the size range of 10 to 125 micrometers.
• ASPM materials include:
• Exemplary APM materials include:
• Torlon 4000 available from BP-Amoco.
• the seal material will generally be located on the radially interior surface of a ring, which is located in the engine so that it circumscribes the tips of the moving airfoils, and the abradable seal will preferably be located in a shallow groove or depression in the ring.
• the depression will have a width which is comparable to and somewhat greater than the width of the compressor blades which will interact with the seal, for example 35-75 mm, and a depth of from 1 to 5 millimeters.
• the ring will be metallic, typically aluminum or titanium, and may be formed in segments.
• the seal material is applied to the groove in the ring or ring segment as follows.
• the groove is cleaned using conventional techniques. We prefer to anodize the cleaned groove surface when producing new parts, when overhauling parts, we have used chromate conversion coating such as Iridite 14-2 from the MacDermid Company in Wallingford, CT on the groove surfaces. Anodizing and chromate conversion are preferred but may not be required for all applications.
• primer material will generally be supplied or specified by the silicone matrix supplier, typical generally useful primers include DC-1200 primer from Dow Coming Company of Midland MI, Visilox V-06 from the Rhodia Corporation of Troy NY and SP270 from the NuSil Corporation of Carpenteria, CA.
• the ring or ring segment is provided with a mandrel which conforms to the inner surface of the ring sealing the groove and leaving an annular cavity to accept the particle filled silicone sealer of the invention.
• the mandrel has one or more apertures through which the silicone polymeric particle containing material can be injected.
• the silicone polymeric particle containing material is injected into and fills the annular cavity. After the annular cavity is filled the apertures through which the material has been injected are closed and the filled ring or ring segment (along with the mandrel) is placed in an oven for curing. Curing is typically performed at temperatures between 300° F (149°C) and 400° F (204°C) for times of one to two hours or as otherwise recommended by the silicone producer.
• the ring and mandrel are removed from the oven, the mandrel is removed, and the ring segment with the groove containing the silicone/particulate abradable rather may be further heat cured as appropriate.
• LSR 5820 or LSR 5830 (produced by the NuSil Corporation; LSR 5820 and LSR 5830 have Shore A Durometer hardnesses of about 20 and 30 respectively after curing) which has been thermally modified with iron oxide is combined with 10 weight per cent of Torlon 4000TF particles having an average size of 55 ⁇ m, and the filled silicone material is processed and cured as previously described, 2 hours at 300° F (149°C) and 2 hours at 400° F (204°C).
• the system is available as R3-2160 from the NuSil Corporation.
• Typical properties for the cured R3-2160 are a Shore A hardness of 32, a tensile strength of 680 psi (4.69 Nmm -2 ) and a tensile elongation of 600%.
• Seals fabricated from the resulting product provide equivalent abradability and 1.9 and 2.4 times the erosion life of current abradable seal materials (containing glass microballoons and as generally described in US 3,575,427) when tested at room temperature and 400° F (204°C) respectively, in a laboratory erosion apparatus using 50-70 mesh Ottawa sand at 800 feet per second (244 ms -1 ) and a 20° incidence angle.
• the term particle as used herein also encompasses low aspect ratio ( ⁇ 10:1) fibre dispersions.

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Structures Of Non-Positive Displacement Pumps (AREA)
• Compositions Of Macromolecular Compounds (AREA)
• Sealing Material Composition (AREA)

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Cited By (7)

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• 2000
  • 2000-11-13 SG SG200006567A patent/SG90198A1/en unknown
  • 2000-12-05 EP EP20000310811 patent/EP1111194B1/fr not_active Expired - Lifetime
  • 2000-12-20 MX MXPA00012937 patent/MXPA00012937A/es active IP Right Grant
  • 2000-12-22 JP JP2000389790A patent/JP2001240745A/ja active Pending
  • 2000-12-22 BR BR0006373A patent/BR0006373A/pt not_active Application Discontinuation
  • 2000-12-23 CN CNB001310526A patent/CN1189519C/zh not_active Expired - Fee Related

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