Comparison of the Dynamic Characteristics of Smooth Annular Seals and Damping Seals

1999 ◽  
Vol 123 (4) ◽  
pp. 857-863 ◽  
Author(s):  
J. M. Darden ◽  
E. M. Earhart ◽  
G. T. Flowers
Keyword(s):  
Experimental Data ◽  
High Speed ◽  
Rocket Engine ◽  
Rotating Machinery ◽  
Test Rig ◽  
Stability Margins ◽  
Annular Seal ◽  
Theoretical Predictions ◽  
High Fluid ◽  
Annular Seals

Annular seals are known to enhance rotordynamic stability margins and minimize vibration response levels in high-speed rotating machinery. Theoretical predictions for the rotordynamic characteristics of annular seals exist but additional experimental data is needed to properly anchor these results. NASA’s Marshall Space Flight Center (MSFC) has developed an annular seal test rig and facility to experimentally characterize axially fed annular seals. Annular seals with deliberately roughened stators (i.e., damping seals) have been shown analytically to increase stability margins of rocket engine turbomachinery by reducing the seal’s whirl frequency ratio. The capabilities of MSFC’s annular seal test rig have been enhanced to allow high fluid inlet preswirl testing that is more representative of actual turbopump seal boundary conditions. The purpose of this paper is to describe the effect of this realistic preswirl on the stabilizing capability of both damping and smooth seals. Centered seal results are presented for both a smooth annular seal and a damping seal. These results were obtained for a range of seal pressure differentials, shaft rotational speeds, and two levels of inlet fluid preswirl.

scholarly journals Comparison of the Dynamic Characteristics of Smooth Annular Seals and Damping Seals

1999 ◽  
Author(s):  
J. Mark Darden ◽  
Eric M. Earhart ◽  
George T. Flowers
Keyword(s):  
Experimental Data ◽  
High Speed ◽  
Rocket Engine ◽  
Rotating Machinery ◽  
Test Rig ◽  
Stability Margins ◽  
Annular Seal ◽  
Theoretical Predictions ◽  
High Fluid ◽  
Annular Seals

Annular seals are known to enhance rotordynamic stability margins and minimize vibration response levels in high-speed rotating machinery. Theoretical predictions for the rotordynamic characteristics of annular seals exist but additional experimental data is needed to properly anchor these results. NASA’s Marshall Space Flight Center (MSFC) has developed an annular seal test rig and facility to experimentally characterize axially-fed annular seals. Annular seals with deliberately roughened stators (i.e. damping seals) have been shown analyticalty to increase stability margins of rocket engine turbomachinery by reducing the seal’s whirl frequency ratio. The capabilities of MSFC’s annular seal test rig have been enhanced to allow high fluid inlet preswirl testing that is more representative of actual turbopump seal bounder conditions. The purpose of this paper is to describe the effect of this realistic preswirl on the stabilizing capability of both damping and smooth seals. Centered seal results are presented for both a smooth annular seal and a damping seal. These results were obtained for a range of seal pressure differentials, shaft rotational speeds, and two levels of inlet fluid preswirl.

scholarly journals Experimental Rotordynamic Characterization of Annular Seals: Facility and Methodology

1998 ◽  
Author(s):  
J. Mark Darden ◽  
Eric M. Earhart ◽  
George T. Flowers
Keyword(s):  
High Speed ◽  
Quality Data ◽  
Test Rig ◽  
Stability Margins ◽  
Rotordynamic Coefficients ◽  
Annular Seal ◽  
Theoretical Predictions ◽  
High Reynolds ◽  
Annular Seals

Annular seals are known to enhance rotordynamic stability margins and minimize vibration response levels in high-speed rotating machinery. Theoretical predictions for the rotordynamic characteristics of annular seals exist but additional experimental data is needed to properly anchor these results. NASA’s Marshall Space Flight Center (MSFC) has developed an annular seal test rig and facility to experimentally characterize axially-fed annular seals. The objective of MSFC’s annular seal test rig is to obtain the rotordynamic coefficients (direct and cross-coupled stiffness, damping, and added mass) for a variety of high Reynolds number annular seals. The MSFC test rig supports centered-seal testing with inlet pressures up to 138 bars (2000 psi) and flow rates of over 946 liters per minute (250 gpm). The rig’s shaft is powered by a 186 kilowatt (250 horsepower) steam turbine capable of rotational speeds of over 20,000 revolutions per minute (rpm). A description of the identification process used to obtain rotordynamic coefficients is given as well as procedures for ensuring quality data. Experimental results for a smooth annular seal with an L/D = 0.5 is presented. Excellent agreement between experimental and theoretical results is obtained.

Experimental Rotordynamic Characterization of Annular Seals: Facility and Methodology

1999 ◽  
Vol 121 (2) ◽  
pp. 349-354 ◽  
Author(s):  
J. M. Darden ◽  
E. M. Earhart ◽  
G. T. Flowers
Keyword(s):  
High Speed ◽  
Quality Data ◽  
Test Rig ◽  
Stability Margins ◽  
Rotordynamic Coefficients ◽  
Annular Seal ◽  
Theoretical Predictions ◽  
High Reynolds ◽  
Annular Seals

Annular seals are known to enhance rotordynamic stability margins and minimize vibration response levels in high-speed rotating machinery. Theoretical predictions for the rotordynamic characteristics of annular seals exist but additional experimental data is needed to properly anchor these results. NASA’s Marshall Space Flight Center (MSFC) has developed an annular seal test rig and facility to experimentally characterize axially fed annular seals. The objective of MSFC’s annular seal test rig is to obtain the rotordynamic coefficients (direct and cross-coupled stiffness, damping, and added mass) for a variety of high Reynolds number annular seals. The MSFC test rig supports centered-seal testing with inlet pressures up to 138 bars (2000 psi) and flow rates of over 946 liters per minute (250 gpm). The rig’s shaft is powered by a 186 kilowatt (250 horsepower) steam turbine capable of rotational speeds of over 20,000 revolutions per minute (rpm). A description of the identification process used to obtain rotordynamic coefficients is given as well as procedures for ensuring quality data. Experimental results for a smooth annular seal with an L/D =0.5 is presented. Excellent agreement between experimental and theoretical results is obtained.

An experimental investigation of a microturbine simulated rotor supported on multileaf gas foil bearings with backing bump foils

2017 ◽  
Vol 232 (9) ◽  
pp. 1169-1180 ◽  
Author(s):  
Bo Zhang ◽  
Shemiao Qi ◽  
Sheng Feng ◽  
Haipeng Geng ◽  
Yanhua Sun ◽  
...  
Keyword(s):  
High Speed ◽  
Preliminary Test ◽  
Journal Bearings ◽  
Rotating Machinery ◽  
System Stability ◽  
Test Rig ◽  
Thrust Bearings ◽  
Foil Bearings ◽  
Simulated System ◽  
First Time

Two multileaf gas foil journal bearings with backing bump foils and one set of gas foil thrust bearings were designed, fabricated, and used in a 100 kW class microturbine simulated rotor system to ensure stability of the system. Meanwhile, a preliminary test rig had been built to verify the simulated system stability. The rotor synchronous and subsynchronous responses were well controlled by using of the gas foil bearings. It is on the multileaf gas foil bearings with backing bump foils that the test was conducted and verified for the first time in open literatures. The success in the experiments shows that the design and fabrication of the rotor and the gas foil bearings can provide a useful guide to the development of the advanced high speed rotating machinery.

Eccentricity Effects on the Rotordynamic Coefficients of Plain Annular Seals: Theory Versus Experiment

1997 ◽  
Vol 119 (3) ◽  
pp. 443-447 ◽  
Author(s):  
O. R. Marquette ◽  
D. W. Childs ◽  
L. San Andres
Keyword(s):  
High Speed ◽  
Small Motion ◽  
Rotordynamic Coefficients ◽  
Annular Seal ◽  
Theory Versus ◽  
High Speed Data ◽  
Static Eccentricity ◽  
Good Signal ◽  
Good Agreement ◽  
Annular Seals

Reliable high-speed data are presented for leakage and rotordynamic coefficients of a plain annular seal at centered and eccentric positions. A seal with L/D = 0.45 was tested, and measured results have good signal-to-noise ratios. The influence on rotordynamic coefficients of pressure drop, running speed, and static eccentricity was investigated. There is an excellent agreement between experimental and theoretical results in the centered position, even for direct inertia terms, which have not shown good agreement with predictions in past studies. However, the rotordynamic coefficients are more sensitive to changes in eccentricity than predicted. These results suggest that, in some cases, annular seals for pumps may need to be treated more like hydrodynamic bearings, with rotordynamic coefficients which are valid for small motion about a static equilibrium position versus the present eccentricity-independent coefficients.

scholarly journals ПАРАМЕТРИЧНІ КОЛИВАННЯ РОТОРУ ТУРБОНАСОСНОГО АГРЕГАТУ НА ШАРИКОПІДШИПНИКАХ

2018 ◽  
pp. 56-61
Author(s):  
Яков Николаевич Иванов ◽  
Олег Петрович Бадун ◽  
Сергей Алексеевич Дешевых ◽  
Александр Юрьевич Стрельченко
Keyword(s):  
Experimental Data ◽  
High Speed ◽  
Rocket Engine ◽  
Final Analysis ◽  
Oscillatory System ◽  
Radial Clearance ◽  
Engineering Practice ◽  
Ball Bearings ◽  
Cooling Liquid ◽  
Bearing Race

This work is dedicated to the problem of ball bearings capacity on the turbopump assembly rotor. Many publications and books have been devoted to solve this problem. The result of research is benefit for designers, technologists and operatives. However, many important questions, which are concerning of ball bearings work, in engineering practice are not sufficiently disclosed. In favor of this is telling the statistic of development of high-speed rotor assemblies. In the total mass of turbopump assembly defects, which appear at the phase of developmental design, more the half of them are belong to the friction nodes, which are including the ball bearings too. The authors are present their own results of the experimental data, which were accumulated as result of the ball bearings tests on the special installation and as part of the turbopump assembly from a Liquid-Propellant Rocket Engine. The defects of ball bearings parts were described and analyzed. The main factors which are worsening the service life of ball bearings in consisting of the turbopump assembly were examined. The kinematics and force interaction of balls with bearing race were examined.In the final analysis was advanced the version of the cause of increased wear of ball bearings high-speed rotor, which consists of the assumption on that during the operation of the bearing, in the radial clearance mode, axial displacements of the balls occur, under the influence of the axial force generated by the flow of the cooling liquid. Also this article shows how these movements of the balls affect the load distribution between the bearing parts and their deterioration.It is assumed that in this mode of operation, in the system "rotor - ball bearing - body" may arise forced axial oscillations. These oscillations are suitable for the term perametric ocillations, since the energy is introduced to the oscillatory system by the periodically changing parameters of the system. In this case, this is the movement of balls, which is expended the energy of rotor rotation or the energy of the flow of cooling liquid.In support of the advanced version, the experimental data on the state of bearings №207Ю and №205Ю were given after the tests with different values of the flow of cooling liquid.

Improving Traditional Balancing Methods for High-Speed Rotors

1996 ◽  
Vol 118 (1) ◽  
pp. 95-99 ◽  
Author(s):  
J. Ling ◽  
Y. Cao
Keyword(s):  
Experimental Data ◽  
Frequency Response ◽  
Frequency Response Function ◽  
High Speed ◽  
Rotating Machinery ◽  
Response Functions ◽  
Frequency Response Functions ◽  
Influence Coefficients ◽  
Mathematical Equations ◽  
Rotor Balancing

This paper introduces frequency response functions, analyzes the relationships between the frequency response functions and influence coefficients theoretically, and derives corresponding mathematical equations for high-speed rotor balancing. The relationships between the imbalance masses on the rotor and frequency response functions are also analyzed based upon the modal balancing method, and the equations related to the static and dynamic imbalance masses and the frequency response function are obtained. Experiments on a high-speed rotor balancing rig were performed to verify the theory, and the experimental data agree satisfactorily with the analytical solutions. The improvement on the traditional balancing method proposed in this paper will substantially reduce the number of rotor startups required during the balancing process of rotating machinery.

scholarly journals Design and development of a modular vibration test rig for combination types of fault in rotating machinery health diagnosis

2019 ◽  
Vol 13 (3) ◽  
pp. 5323-5333
Author(s):  
S. M. Silahuddin ◽  
A. M. Aizuddin ◽  
S. Mohamaddan ◽  
S. T. Syed Shazali ◽  
M. S. Z. M. Suffian ◽  
...  
Keyword(s):  
Experimental Data ◽  
Educational Environment ◽  
Rotating Machinery ◽  
Vibration Test ◽  
Deformation Pattern ◽  
Test Rig ◽  
Final Design ◽  
Multiple Configurations ◽  
Health Diagnosis ◽  
Rotating Machineries

As a basis to real application of rotating machineries operation, a test rig imitating the operation is designed for the research environment. The purpose of this study is to design a modular test rig which is able to facilitate different fault component combinations and evaluate the deformation pattern of the fabricated test rig. Rotating machineries face the probability of having simultaneous different faults and the study of this condition is limited. The designed test rig could be arranged into multiple configurations by adding or excluding desired components due to its modularity. This will be useful to study the response of each component during operation as well as the response of combinations of fault components. Included in this study is the analysis of the design, the components of the test rig and the final design as well as the experimental data results of the fabricated test rig. This test rig is beneficial for understanding the vibrational behavior of components especially in educational environment.

Numerical Modeling of Rotordynamic Coefficients for Deliberately Roughened Stator Gas Annular Seals

2006 ◽  
Vol 129 (2) ◽  
pp. 424-429 ◽  
Author(s):  
Gocha Chochua ◽  
Thomas A. Soulas
Keyword(s):  
Transient Analysis ◽  
Test Rig ◽  
One Dimensional ◽  
Design And Optimization ◽  
Rotordynamic Coefficients ◽  
Seal Design ◽  
Annular Seal ◽  
Rotor Surface ◽  
Good Agreement ◽  
Annular Seals

A method is proposed for computations of rotordynamic coefficients of deliberately roughened stator gas annular seals using computational fluid dynamics. The method is based on a transient analysis with deforming mesh. Frequency-dependent direct and cross-coupled rotordynamic coefficients are determined as a response to an assigned rotor surface periodic motion. The obtained numerical results are found to be in good agreement with the available test data and one-dimensional tool predictions. The method can be used as a research tool or as a virtual annular seal test rig for seal design and optimization.

scholarly journals Transient Behavior of a Radial Vaneless Diffuser

2011 ◽  
Author(s):  
Antoine Dazin ◽  
Patrick Dupont ◽  
Guy Caignaert ◽  
Ge´rard Bois
Keyword(s):  
Experimental Data ◽  
High Speed ◽  
Laser Sheet ◽  
High Repetition Rate ◽  
Optical Methods ◽  
Pressure Measurements ◽  
Vaneless Diffuser ◽  
Test Rig ◽  
Unsteady Pressure ◽  
Unsteady Pressure Measurements

The paper refers to the behavior of a radial flow pump vaneless diffuser during a starting period. Results obtained with a 1D numerical model are compared with some new experimental data which have been obtained using 2D/3C High repetition rate PIV within the diffuser coupled with unsteady pressure measurements. These tests have been performed on a test rig with a radial impeller matched with a vaneless diffuser. They have been made in air, on a test rig well adapted for studies on interactions between impeller and diffuser, as well as for the use of optical methods and especially Particle Image Velocimetry (PIV) as there is no volute downstream of the diffuser. The present study refers to new experiments combining pressure measurements and 2D/3C High Speed PIV at partial flow rates within a vaneless diffuser with a large outlet radius. Four Bru¨el & Kjaer condenser microphones are used for the unsteady pressure measurements. They were flush mounted on the shroud side of the diffuser wall and on the suction pipe of the pump. The sampling frequency was 2048 Hz. For PIV measurements, the laser sheet was generated by a Darwin PIV ND:YLF Laser at three heights within the diffuser. PIV snapshots have been recorded by two identical CMOS cameras. A home made software has been used for the images treatment. The results consist in fields of 80 × 120 mm2 and 81 × 125 velocity vectors with a temporal resolution of 250 velocity maps per second. For each flow rate and each laser sheet height in the diffuser, two acquisitions of about 1500 velocity maps have been realised. The experimental data are compared with the ones provided by a 1D transient model of the flow within the diffuser.

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