Experimental Evaluation of a Metal Mesh Bearing Damper

1999 ◽  
Author(s):  
Mark Zarzour ◽  
John Vance
Keyword(s):  
Elevated Temperatures ◽  
Test Facility ◽  
Squeeze Film ◽  
Gas Generator ◽  
Metal Mesh ◽  
Previous Investigator ◽  
Spreadsheet Program ◽  
Squirrel Cage ◽  
Power Turbine ◽  
Squeeze Film Dampers

Metal mesh is a commercially available material used in many applications including seals, heat shields, filters, gaskets, aircraft engine mounts, and vibration absorbers. This material has been tested by the authors as a bearing damper in a rotordynamic test rig. The test facility was originally used to support the design of a turboprop engine, developing squirrel cages and squeeze film dampers for both the gas generator and power turbine rotors. To design the metal mesh damper, static stiffness and dynamic rap test measurements were first made on metal mesh samples in a specially designed nonrotating test fixture. These property tests were performed on samples of various densities and press fits. One sample was also tested in an Instron machine as an ancillary and redundant way to determine the stiffness. Using the stiffness test results and equations derived by a previous investigator, a spreadsheet program was written and used to size metal mesh donuts that have the radial stiffness value required to replace the squirrel cage in the power turbine. The squirrel cage and squeeze film bearing damper developed for the power turbine rotor was then replaced by a metal mesh donut sized by the computer code. Coast down tests were conducted through the first critical speed of the power turbine. The results of the metal mesh tests are compared with those obtained from previous testing with the squeeze film damper and Show that the metal mesh damper has the same damping as the squeeze film at room temperature but does not lose its damping at elevated temperatures up to 103 °C. Experiments were run under several different conditions, including balanced rotor, unbalanced rotor, heated metal mesh, and wet (with oil) metal mesh. The creep, or sag, of the metal mesh supporting the rotor weight was also measured over a period of several weeks and found to be very small. Based on these tests, metal mesh dampers appear to be a viable and attractive substitute for squeeze film dampers in gas turbine engines. The advantages shown by these tests include less variation of damping with temperature, ability to handle large rotor unbalance, and the ability (if required) to operate effectively in an oil free environment. Additional testing is required to determine the endurance properties, the effect of high impact or maneuver loads, and the ability to sustain blade loss loads (which squeeze films cannot handle).

Experimental Evaluation of a Metal Mesh Bearing Damper

2000 ◽  
Vol 122 (2) ◽  
pp. 326-329 ◽  
Author(s):  
Mark Zarzour ◽  
John Vance
Keyword(s):  
Elevated Temperatures ◽  
Test Facility ◽  
Squeeze Film ◽  
Gas Generator ◽  
Metal Mesh ◽  
Previous Investigator ◽  
Spreadsheet Program ◽  
Squirrel Cage ◽  
Power Turbine ◽  
Squeeze Film Dampers

Metal mesh is a commercially available material used in many applications including seals, heat shields, filters, gaskets, aircraft engine mounts, and vibration absorbers. This material has been tested by the authors as a bearing damper in a rotordynamic test rig. The test facility was originally used to support the design of a turboprop engine, developing squirrel cages and squeeze film dampers for both the gas generator and power turbine rotors. To design the metal mesh damper, static stiffness and dynamic rap test measurements were first made on metal mesh samples in a specially designed nonrotating test fixture. These property tests were performed on samples of various densities and press fits. One sample was also tested in an Instron machine as an ancillary and redundant way to determine the stiffness. Using the stiffness test results and equations derived by a previous investigator, a spreadsheet program was written and used to size metal mesh donuts that have the radial stiffness value required to replace the squirrel cage in the power turbine. The squirrel cage and squeeze film bearing damper developed for the power turbine rotor was then replaced by a metal mesh donut sized by the computer code. Coast down tests were conducted through the first critical speed of the power turbine. The results of the metal mesh tests are compared with those obtained from previous testing with the squeeze film damper and show that the metal mesh damper has the same damping as the squeeze film at room temperature but does not lose its damping at elevated temperatures up to 103°C. Experiments were run under several different conditions, including balanced rotor, unbalanced rotor, heated metal mesh, and wet (with oil) metal mesh. The creep, or sag, of the metal mesh supporting the rotor weight was also measured over a period of several weeks and found to be very small. Based on these tests, metal mesh dampers appear to be a viable and attractive substitute for squeeze film dampers in gas turbine engines. The advantages shown by these tests include less variation of damping with temperature, ability to handle large rotor unbalance, and the ability (if required) to operate effectively in an oil free environment. Additional testing is required to determine the endurance properties, the effect of high impact or maneuver loads, and the ability to sustain blade loss loads (which squeeze films cannot handle). [S0742-4795(00)01002-4]

scholarly journals Coupling vibration analysis of turbine shared support rotor-bearing system with squeeze film dampers

2021 ◽  
Author(s):  
Jiaqi Han ◽  
Guihuo Luo ◽  
Fei Wang ◽  
Wei Chen ◽  
Lulu Liu ◽  
...  
Keyword(s):  
Turbine Rotor ◽  
Test System ◽  
Squeeze Film ◽  
Gas Generator ◽  
Support Structure ◽  
Coupling Vibration ◽  
Power Turbine ◽  
Squeeze Film Dampers ◽  
Rotor Bearing ◽  
Bearing System

Abstract The turbine shared support structure is used widely in aeroengines, but theoretical and experimental research on a rotor-bearing system containing a shared turbine support structure is lacking. This paper reports research into the coupling vibration response of a squeeze-film-damper rotor-bearing system that has two spools with different rotation speeds and is supported by a turbine shared support structure. The problem is addressed by means of rotor-bearing system tests and the finite-element method. Based on the features of a turboshaft engine with a turbine shared support structure, a rotor-bearing test system with a shared support structure is designed, and a dynamic model of the test system is built based on Timoshenko beam elements. The experimental and simulation results indicate that the unbalanced response of the rotor-bearing system with a shared support structure may involve either the sum or difference of the fundamental frequencies of the rotors of the gas generator and power turbine. The simulations show that the imbalance of the power turbine rotor, the radial and bending stiffnesses of the shared support structure, and the radial clearances of squeeze film dampers at the rear of the rotor-bearing system all affect the coupling response. The amplitude of the coupling response can be suppressed effectively by (i) selecting reasonable parameter values for the turbine shared support structure and (ii) exerting strict control over the spool imbalance.

Experimental Evaluation of a Metal Mesh Bearing Damper in Parallel With a Structural Support

2001 ◽  
Author(s):  
Eyad M. Al-Khateeb ◽  
John M. Vance
Keyword(s):  
Stainless Steel ◽  
Wire Mesh ◽  
Squeeze Film ◽  
Hysteretic Model ◽  
Metal Mesh ◽  
Critical Speeds ◽  
Squirrel Cage ◽  
Hysteretic Damping ◽  
Damping Model ◽  
Copper Mesh

In a previous ASME paper experiments were reported on metal mesh bearing dampers (MMD) that were tested in a power turbine rotor at speeds up to 12,000 rpm. They were made of 0.229 mm stainless steel 304 wire mesh, compressed to 57% density, which is close to the maximum density that was economically available. After balancing, a level of vibration was achieved similar to that previously observed with squeeze film dampers. These experiments showed that the MMD could suppress vibration amplitudes of the 22.7 kg rotor at critical speeds of 4,000 rpm and 9,300 rpm. Much of the testing showed the rotor having little or no response to unbalance on coastdown through the critical speeds. The donut-shaped MMD in those tests were the only bearing supports; no squirrel cages were used. A question was raised about the feasibility of using MMD in parallel with a squirrel cage bearing support so that the stiffness can be controlled independently of the damping. This paper presents experimental results for metal mesh dampers with a squirrel cage as a parallel bearing support. Experiments with copper mesh as seal elements (on another project) had indicated that copper mesh has higher damping than stainless steel, so copper was chosen for these experiments. Both a linear viscous damping model and a hysteretic damping model were investigated. Some hysteretic damping models predict that damping depends on stiffness. A different hysteretic model turned out to be useful and promising as a prediction model for two reasons: a) it fits the measured data, and b) it predicts that the damping is not lost if the MMD is put in parallel with a steel structure such as a squirrel cage bearing support. The measurements reported here support the validity of that prediction.

Unbalance Response of a Two Spool Gas Turbine Engine With Squeeze Film Bearings

1981 ◽  
Author(s):  
E. J. Gunter ◽  
D. F. Li ◽  
L. E. Barrett
Keyword(s):  
Gas Turbine ◽  
Nonlinear Effects ◽  
Forced Response ◽  
Squeeze Film ◽  
Gas Generator ◽  
Main Bearing ◽  
Resonant Condition ◽  
Turbine Engine ◽  
Generator Rotor ◽  
Power Turbine

This paper presents a dynamic analysis of a two-spool gas turbine helicopter engine incorporating intershaft rolling element bearings between the gas generator and power turbine rotors. The analysis includes the nonlinear effects of a squeeze film bearing incorporated on the gas generator rotor. The analysis includes critical speeds and forced response of the system and indicates that substantial dynamic loads may be imposed on the intershaft bearings and main bearing supports with an improperly designed squeeze film bearing. A comparison of theoretical and experimental gas generator rotor response is presented illustrating the nonlinear characteristics of the squeeze film bearing. It was found that large intershaft bearing forces may occur even though the engine is not operating at a resonant condition.

Design Equations for Wire Mesh Bearing Dampers in Turbomachinery

2005 ◽  
Author(s):  
Vivek V. Choudhry ◽  
John M. Vance
Keyword(s):  
Turbine Rotor ◽  
Wire Mesh ◽  
Squeeze Film ◽  
Operational Parameters ◽  
Temperature Changes ◽  
Turbine Oil ◽  
Power Turbine ◽  
Squeeze Film Dampers ◽  
Stiffness And Damping ◽  
Asme Paper

In a previous ASME paper the second author reported experiments on wire mesh bearing dampers (WMD) incorporated in a power turbine rotor-bearing system in order to enable a direct comparison between WMD and squeeze film dampers (SFD). The results showed that both WMD and SFD perform equally well for reducing the rotordynamic amplitudes of vibration. Moreover the WMD were found to have significant advantages over SFD. The damping provided by the wire mesh is independent of temperature changes and presence of turbine oil. Experiments by another investigator showed that WMD are capable of sustaining more than twice the unbalance as compared to SFD, which promises possible application to withstand blade loss loads. This paper presents empirically developed non-dimensional design equations for WMD, capable of predicting stiffness and damping for a wire mesh ‘donut’ subject to changes in various design, installation, and operational parameters.

scholarly journals Development and Field Experience of a New 29000 HP Gas Turbine

1980 ◽  
Author(s):  
J. K. Hubbard ◽  
C. Austin
Keyword(s):  
Gas Turbine ◽  
Field Experience ◽  
Performance Test ◽  
High Efficiency ◽  
Test Facility ◽  
Gas Generator ◽  
Initial Field ◽  
Power Turbine ◽  
Exhaust Heat ◽  
Gas Turbine Exhaust

The paper describes the development and initial field experience with a new high efficiency 26,000/30,000 hp gas turbine. Exhaust heat from the power turbine was used to boost the installation thermal efficiency and provide icing protection for the inlet. Wherever possible, proven power turbine design concepts were combined with the advances of a “second generation” aircraft derivative gas generator to produce a reliable machine which was introduced with a minimum of development time. To assure field success, a special test facility was constructed and the unit subjected to a full load mechanical and performance test under simulated field condition.

A Theoretical and Experimental Investigation of a Gas Operated Bearing Damper for Turbomachinery: Part I — Theoretical Model and Predictions

1993 ◽  
Author(s):  
Padmanabhan Sundararajan ◽  
John M. Vance
Keyword(s):  
Theoretical Model ◽  
Squeeze Film ◽  
Working Fluid ◽  
Previous Theory ◽  
Damping Characteristics ◽  
Squirrel Cage ◽  
Squeeze Film Dampers ◽  
Theoretical Predictions ◽  
Current Design ◽  
Gas Damper

Abstract This is the first (Part I) of two papers describing recent results of a research program directed at developing a vibration damper suitable for high temperature turbomachinery applications. It is expected that such dampers will replace squeeze-film dampers that use oil as the working fluid and have limitations at higher temperatures. A novel gas operated bearing damper has been analytically and experimentally evaluated for its damping characteristics. Theory that is based on the isentropic assumptions predicts the damper performance characteristics reasonably well. A maximum damping level of 13.2 lb-s/in at a frequency of 100 hz was measured with a single actuator of the gas damper and, since many such actuators can be placed circumferentially around the squirrel cage, considerable damping levels can be realized. The study also shows that significantly higher damping levels can be achieved by modifying the current design. Part I describes the theoretical model that has been developed based on isentropic assumptions. This model is an improved version of the previous theory [1,2] and includes the supply groove effects, dynamic area changes of the inlet feeding holes and the effects of flow choking on damper behavior. The governing equations are derived and theoretical predictions using these equations have been made for the three hardwares that were experimentally investigated (see Part II).

scholarly journals Design and Development of a 12,500-Hp Gas Turbine

1971 ◽  
Author(s):  
C. Austin
Keyword(s):  
Gas Turbine ◽  
Electrical Power ◽  
Load Test ◽  
Test Facility ◽  
Gas Generator ◽  
Design Concepts ◽  
Power Turbine ◽  
Gas Generators ◽  
Design Speed ◽  
Simulated Field

This paper outlines the major design considerations and development experience of a 12,500-hp dual-shaft gas turbine. The unit uses an aircraft derivative gas turbine as the gas generator and is designed to operate in an attended or unattended station without external electrical power above 60 per cent of design speed. Proven power turbine design concepts were combined with the advantages of a variety of highly developed gas generators to produce a reliable machine which could be introduced with a minimum of development time. A special test facility was constructed to subject the unit to a full load test under conditions which simulated field operation.

Development of High Efficient 30MW Class Gas Turbine: The Kawasaki L30A

2012 ◽  
Author(s):  
Ryozo Tanaka ◽  
Take Koji ◽  
Masanori Ryu ◽  
Akinori Matsuoka ◽  
Atsushi Okuto
Keyword(s):  
Gas Turbine ◽  
Pressure Ratio ◽  
Test Facility ◽  
Gas Generator ◽  
Pressure Losses ◽  
Power Turbine ◽  
High Efficient ◽  
Cooling Design ◽  
Power Application ◽  
Technical Features

Kawasaki Heavy Industries (KHI) will launch the first unit of the L30A gas turbine, rated output of 30.9MW, and 41.2% of thermal efficiency. The L30A is a twin-shaft gas turbine designed for combined heat and power application (CHP) with lower emissions. The newly developed 14-stage compressor has a pressure ratio of 24.5 with an air flow of 86.5 kg/sec. KHI’s proven dry low emission (DLE) technologies are adapted to the combustion design, and NOx emission of 15 ppm (15% = O2) has been achieved. Also, the newly designed 2-stage gas generator turbine (GGT) employs the proven cooling design with conjugate heat transfer and flow (CHT) analysis, and 3-stage power turbine (PT) has the inter-locking type tip shroud which reduces vibration level for wide operating range of PT with lower pressure losses. The in-house verification tests have been conducted since 2010, to confirm design targets such as performance, emission, vibrations and temperatures were verified in exclusive test facility for the L30A. This paper describes the technical features of the L30A, the development activities and some verification test results.

Dynamic Modeling of a Dual Clearance Squeeze Film Damper: Part III

2005 ◽  
Author(s):  
L. Moraru ◽  
F. Dimofte ◽  
S. Cioc ◽  
T. G. Keith ◽  
D. P. Fleming
Keyword(s):  
Experimental Data ◽  
High Speed ◽  
Rotating Machinery ◽  
Operating Conditions ◽  
Squeeze Film ◽  
Squeeze Film Damper ◽  
Squirrel Cage ◽  
Squeeze Film Dampers ◽  
Abnormal Operating Conditions ◽  
Oil Films

Squeeze film dampers (SFD) are devices utilized to control vibrations of the shafts of high-speed rotating machinery. A dual squeeze film damper (DSFD) consists of two squeeze film bearings that are separated by a sleeve, which is released when the rotor experiences abnormal operating conditions. In this part of our study of DSFD we analyze the case when both the inner and the outer oil films are active and the separating sleeve is supported by a squirrel cage. Numerical results are compared with the experimental data.

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