Abstract: A dual-film damper has a housing defining an annular damper fluidly connected to a source of pressurized oil. First and second damper rings are coaxially nested within the damper cavity. A first set of spacers allows for the formation of a first oil film annulus between the first and second damper rings. A second set of spacers allows for the formation of a second oil film annulus between the second damper ring and the housing. The first and second oil film annuli have a thickness-to-length ratio (T/L) selected to provide a desired damping capacity.

Abstract: A dual-film damper has a housing defining an annular damper fluidly connected to a source of pressurized oil. First and second damper rings are coaxially nested within the damper cavity. A first set of spacers allows for the formation of a first oil film annulus between the first and second damper rings. A second set of spacers allows for the formation of a second oil film annulus between the second damper ring and the housing. The first and second oil film annuli have a thickness-to-length ratio (T/L) selected to provide a desired damping capacity.

Abstract: A multi-film oil damper has an annular damper cavity defined within a housing between a radially outward wall, a first radially extending side wall and a second radially extending side wall. Nested damper rings are disposed within the annular damper cavity for defining squeeze film annuli therebetween. The squeeze film annuli are fluidly connected in parallel to an inlet gallery.

Abstract: A multi-film oil damper has a housing defining an annular damper cavity between a radially outward wall and radially extending side walls. The annular damper cavity has an oil inlet configured for connection to a source of pressurized oil. A closure ring defines a radially inward boundary of the annular damper cavity. First and second damper rings are nested together coaxially within the annular damper cavity. At least one of the first damper ring and the second damper ring has an axial end radial thickness less than an intermediate-portion radial thickness.

Abstract: A multi-film oil damper for accommodating radial movement of a rotary shaft bearing relative to a bearing housing, the multi-film oil damper comprising: an annular damper cavity defined within the bearing housing between a radially outward wall, a first radially extending side wall and a second radially extending side wall, the annular damper cavity having an oil inlet in the radially outward wall, the oil inlet being in communication with a source of pressurized oil; an inner damper ring having axial ends abutting the first and second radially extending side walls of the annular damper cavity; a plurality of outer damper rings coaxially nested between the inner damper ring and the radially outward wall, each outer damper ring having axial ends adjacent the first and second radially outward walls of the annular damper cavity, each outer damper ring having a first cylindrical surface and a second cylindrical surface; a spacer ring disposed at each axial end of the plurality of outer damper rings, a contact sur

Abstract: A multi-film oil damper has a housing defining an annular damper cavity having an oil inlet in communication with a source of pressurized oil. A plurality of nested damper rings is disposed within the annular damper cavity, the plurality of nested damper rings defining a plurality of squeeze film annuli. Spacer rings are disposed adjacent opposed ends of the damper rings. A contact surface of the spacer rings extends radially beyond a first cylindrical surface of an associated damper ring for engaging a second cylindrical surface of an adjacent damper ring. Recesses are defined in the second cylindrical surface of the damper rings, the recesses fluidly communicating between the squeeze film annuli and the oil inlet.

Abstract: A multi-film oil damper for accommodating radial movement of a rotary shaft bearing relative to a bearing housing, the multi-film oil damper comprising: an annular damper cavity defined within the bearing housing between a radially outward wall, a first radially extending side wall and a second radially extending side wall, the annular damper cavity having an oil inlet in the radially outward wall, the oil inlet being in communication with a source of pressurized oil; an inner damper ring having axial ends abutting the first and second radially extending side walls of the annular damper cavity; a plurality of outer damper rings coaxially nested between the inner damper ring and the radially outward wall, each outer damper ring having axial ends adjacent the first and second radially outward walls of the annular damper cavity, each outer damper ring having a first cylindrical surface and a second cylindrical surface; a spacer ring disposed at each axial end of the plurality of outer damper rings, a contact sur

Abstract: A multi-film oil damper has a housing defining an annular damper cavity having an oil inlet in communication with a source of pressurized oil. A plurality of nested damper rings is disposed within the annular damper cavity, the plurality of nested damper rings defining a plurality of squeeze film annuli. Spacer rings are disposed adjacent opposed ends of the damper rings. A contact surface of the spacer rings extends radially beyond a first cylindrical surface of an associated damper ring for engaging a second cylindrical surface of an adjacent damper ring. Recesses are defined in the second cylindrical surface of the damper rings, the recesses fluidly communicating between the squeeze film annuli and the oil inlet.

Abstract: A multi-film oil damper for accommodating radial movement of a rotary shaft bearing relative to a bearing housing, the multi-film oil damper comprising: an annular damper cavity defined within the bearing housing between a radially outward wall, a first radially extending side wall and a second radially extending side wall, the annular damper cavity having an oil inlet in the radially outward wall, the oil inlet being in communication with a source of pressurized oil; an inner damper ring having axial ends abutting the first and second radially extending side walls of the annular damper cavity; a plurality of outer damper rings coaxially nested between the inner damper ring and the radially outward wall, each outer damper ring having axial ends adjacent the first and second radially outward walls of the annular damper cavity, each outer damper ring having a first cylindrical surface and a second cylindrical surface; a plurality of spacer bosses circumferentially spaced apart at each axial end of the plurality

Abstract: A multi-film oil damper for accommodating radial movement of a rotary shaft bearing relative to a bearing housing, the multi-film oil damper comprising: an annular damper cavity defined within the bearing housing between a radially outward wall, a first radially extending side wall and a second radially extending side wall, the annular damper cavity having an oil inlet in the radially outward wall, the oil inlet being in communication with a source of pressurized oil; an inner damper ring having axial ends abutting the first and second radially extending side walls of the annular damper cavity; a plurality of outer damper rings coaxially nested between the inner damper ring and the radially outward wall, each outer damper ring having axial ends adjacent the first and second radially outward walls of the annular damper cavity, each outer damper ring having a first cylindrical surface and a second cylindrical surface; a plurality of spacer bosses circumferentially spaced apart at each axial end of the plurality

Abstract: A multi-film oil damper suited for accommodating radial movement of a rotary shaft bearing relative to a bearing housing, the multi-film oil damper comprising: an annular damper cavity defined within the bearing housing between a radially outward wall and radially extending side walls; an inner damper ring; an outer damper ring disposed between the inner damper ring and the radially outward wall of the annular damper cavity; wherein the annular damper cavity has an oil inlet in communication with a source of pressurized oil; and wherein a radial thickness of the inner damper ring exceeds a radial thickness of the outer damper ring.

Abstract: A multi-film oil damper has an annular damper cavity defined within a housing between a radially outward wall, a first radially extending side wall and a second radially extending side wall. Nested damper rings are disposed within the annular damper cavity for defining squeeze film annuli therebetween. The squeeze film annuli are fluidly connected in parallel to an inlet gallery.

Abstract: A multi-film oil damper has a housing defining an annular damper cavity between a radially outward wall and radially extending side walls. The annular damper cavity has an oil inlet configured for connection to a source of pressurized oil. A closure ring defines a radially inward boundary of the annular damper cavity. First and second damper rings are nested together coaxially within the annular damper cavity. At least one of the first damper ring and the second damper ring has an axial end radial thickness less than an intermediate-portion radial thickness.

Abstract: A multi-film oil damper suited for accommodating radial movement of a rotary shaft bearing relative to a bearing housing, the multi-film oil damper comprising: an annular damper cavity defined within the bearing housing between a radially outward wall and radially extending side walls; an inner damper ring; an outer damper ring disposed between the inner damper ring and the radially outward wall of the annular damper cavity; wherein the annular damper cavity has an oil inlet in communication with a source of pressurized oil; and wherein a radial thickness of the inner damper ring exceeds a radial thickness of the outer damper ring.

Abstract: A method of balancing a spool of a gas turbine engine, the spool including a forward rotor assembly and an aft rotor assembly separated by a spacer, the method comprising: balancing the forward rotor assembly and the aft rotor assembly independently from one another using conventional balancing techniques; and mathematically modeling the spool; applying a modeled axial load to the modeled spool to determine a trim weight which would balance the spool when subjected to the modeled axial load; and physically placing the trim weight to one of the forward rotor assembly and the aft rotor assembly.

Abstract: A method of balancing a spool of a gas turbine engine, the spool including a forward rotor assembly and an aft rotor assembly separated by a spacer, the method comprising: balancing the forward rotor assembly and the aft rotor assembly independently from one another using conventional balancing techniques; and mathematically modeling the spool; applying a modeled axial load to the modeled spool to determine a trim weight which would balance the spool when subjected to the modeled axial load; and physically placing the trim weight to one of the forward rotor assembly and the aft rotor assembly.

Abstract: Disclosed is a measurement system for measuring subsurface resistivity. The surfaces of interest are, for example, engineered surfaces such as roads and dams, and non-engineered surfaces such as greenfield sites. The measurement system may also be used on biological materials. The system includes signal input electrodes for inputting an input signal into subsurface material by capacitive coupling. Pairs of signal detection electrodes allow capacitive coupling detection of a detectable signal caused by the input signal in at least some of the subsurface material. A phase-sensitive meter such as a lock-in amplifier is provided to measure the amplitude and phase of the detectable signal.

Abstract: Disclosed is a measurement system for measuring subsurface resistivity. The surfaces of interest are, for example, engineered surfaces such as roads and dams, and non-engineered surfaces such as greenfield sites. The measurement system may also be used on biological materials. The system includes signal input electrodes for inputting an input signal into subsurface material by capacitive coupling. Pairs of signal detection electrodes allow capacitive coupling detection of a detectable signal caused by the input signal in at least some of the subsurface material. A phase-sensitive meter such as a lock-in amplifier is provided to measure the amplitude and phase of the detectable signal.