Experimental and Analytical Investigation of Squeeze Film Bearing Damper Forces Induced by Offset Circular Whirl Orbits

1978 ◽  
Vol 100 (3) ◽  
pp. 549-557 ◽  
Author(s):  
P. N. Bansal ◽  
D. H. Hibner
Keyword(s):  
Basic Research ◽  
Aircraft Engine ◽  
Analytical Investigation ◽  
Operating Conditions ◽  
Squeeze Film ◽  
Test Results ◽  
Simple Method ◽  
Oil Film ◽  
Pressure Transducers ◽  
Pressure Profiles

A basic research program was conducted to investigate the hydrodynamic forces of a squeeze film bearing damper. These forces were induced by controlled offset circular whirl orbits of the damper journal. The orbits were mechanically produced by eccentric damper rings and cams in a specially designed, end sealed test rig. Aircraft engine damper geometry and operating conditions were simulated. The instantaneous circumferential pressure profiles, for specific orbits, were measured by eight high response pressure transducers. From these data, twelve composite pressure plots were developed; each was numerically integrated to determine the damper forces corresponding to every 30 deg position of the damper center, i.e., 0–360 deg. The variations in oil film thickness data were monitored via two proximity probes. A numerical method which uses the proximity test data and the damper geometry to calculate the instantaneous values of damper center eccentricity (e), phase angle (φ), radial velocity (e˙), and whirl velocity (φ˙) is presented. These test values are required to compare theory with test. Since the data reduction for offset orbits is extremely complicated, this simple method was found to be very useful in analyzing the test results. Test results for pressure profiles as well as damper forces were compared with theoretical predictions. Agreement was good. The analysis is based on “long bearing” solution of Reynolds equation and includes the effect of inlet and cavitation pressures. For the cavitated oil film, inlet pressure was shown to have important effect on damper forces.

Investigation of Squeeze Film Damper Forces Produced by Circular Centered Orbits

1978 ◽  
Vol 100 (1) ◽  
pp. 15-21 ◽  
Author(s):  
E. Feder ◽  
P. N. Bansal ◽  
A. Blanco
Keyword(s):  
Aircraft Engine ◽  
Analytical Investigation ◽  
Operating Conditions ◽  
Squeeze Film ◽  
Oil Viscosity ◽  
Pressure Transducers ◽  
Pressure Distributions ◽  
Pressure Profiles ◽  
Force Components ◽  
Type Pressure

This paper presents the results of an experimental and analytical investigation of the dynamic forces generated by a squeeze film bearing damper constrained to move in circular centered orbits. These orbits were mechanically produced in a specially designed, end sealed, test rig. Aircraft engine damper geometry and operating conditions were simulated. The effect of journal speed, oil viscosity, inlet pressure, and eccentricity ratio on the damper performance was studied. The pressure distributions about the journal were measured for each test condition by high-response diaphragm-type pressure transducers. These pressure profiles were numerically integrated to determine the force components of the squeeze film. Experimental results were compared to an analysis which is summarized in this paper and included the effects of inlet and cavitation pressures. The “long bearing theory” was found to be reasonably accurate in predicting the shape and magnitude of the pressure distribution. Considerable emphasis was directed to the study of the circumferential pressure distributions between 180 deg and 360 deg since aircraft engine dampers generally operate in this region. For the cavitated film (i.e., pressure distributions less than 360 deg), accurate prediction of the damper forces was found to be critically dependent on the effect of inlet and cavitation pressures.

An Investigation into the Performance of Dynamically Loaded Journal Bearings: Theory

1966 ◽  
Vol 181 (2) ◽  
pp. 1-8 ◽  
Author(s):  
T. Lloyd ◽  
R. Horsnell ◽  
H. McCallion
Keyword(s):  
High Speed ◽  
Numerical Solutions ◽  
Rotational Velocity ◽  
Operating Conditions ◽  
Squeeze Film ◽  
Maximum Pressure ◽  
Oil Film ◽  
Pressure Distributions ◽  
Routine Design ◽  
Oil Flow

The main and big-end bearings in reciprocating machinery are subjected to loads varying both in magnitude and direction. At present the only guidance available to the designer of such bearings may be a comparison of bearing performance in similar engines and it is fundamental to the introduction of improved design criteria that a prediction of the journal locus, peak pressures, and oil flow be readily available for a proposed geometry and loading. In this paper a numerical method of solution of this problem, utilizing a high-speed digital computer with a large one-level store, is described. The method rests on the assumption of isothermal conditions in the oil film and on the unimportance of the inertia forces associated with the journal accelerations. Numerical solutions of the Reynolds equation are obtained and stored for both wedge and squeeze film terms, at a number of journal eccentricities, by using an iterative method. The oil film force and the derivatives of this force with respect to both the journal centre position and its velocity are then found by summing these pressure distributions in the required proportions. At intermediate eccentricities, the required pressure distributions are obtained by interpolation before they are summed. The journal centre locus is obtained from a step-by-step solution of two simultaneous, ordinary differential equations involving the oil film data and the external load. In addition to the locus, the maximum pressure at any instant, the oil flow, and the friction work are calculated. For big-end bearings, journal rotational velocity is not constant and this is allowed for in the analysis. The computer program described needs no input apart from the bearing geometry and operating conditions and, because of refinement of the iteration and the integration procedures, it is economic to use for routine design studies.

Calculated Rotordynamic Behaviour of a Twin Spool Engine and the Comparison With Test Results

1995 ◽  
Author(s):  
B. Domes ◽  
H. Hartmüller ◽  
G. Tokar ◽  
G. Wang
Keyword(s):  
Dynamic Behaviour ◽  
Complex Structure ◽  
Operating Conditions ◽  
Squeeze Film ◽  
Test Results ◽  
Engine Model ◽  
Damping Characteristics ◽  
Resonance Frequencies ◽  
Squeeze Film Dampers ◽  
Good Agreement

Abstract The new BR 700 series of twin spool engines, of the thrust class of 15,000 to 20,000 pounds, is being developed for business jets. In this paper the rotordynamic vibration analysis is performed with a detailed whole engine model including both rotors, bearings with oil squeeze film dampers and squirrel cages, the engine structure, the mounts and the fuselage. The analytical method is described and some calculated results are presented. The effectiveness of the oil squeeze film dampers on all main bearings will be demonstrated. The comparison of the analytical and the measured results gives a good agreement in the resonance frequencies and in the damping characteristics. It also shows that a linear analysis can describe with sufficient accuracy the dynamic behaviour of such a complex structure like a twin spool engine under normal operating conditions.

Investigation of the Response of an Air Blast Atomizer Combustion Chamber Configuration on Forced Modulation of Air Feed at Realistic Operating Conditions

2003 ◽  
Vol 125 (4) ◽  
pp. 872-878 ◽  
Author(s):  
C. Hassa ◽  
J. Heinze ◽  
K. Stursberg
Keyword(s):  
Combustion Chamber ◽  
Liquid Fuel ◽  
Aircraft Engine ◽  
Operating Conditions ◽  
Pressure Data ◽  
Pressure Transducers ◽  
Flame Tube ◽  
Elevated Pressures ◽  
Resonant Behavior ◽  
Burner Nozzle

DLR investigated forced combustion oscillations of two liquid fuel burners in a research combustion chamber at elevated pressures simulating idle conditions of aircraft engine combustors. The work was performed in collaboration with MTU Munich. An existing combustion chamber with optical access, capable to operate up to 20 bar, was upgraded with an air flow pulsator, that bypasses air from the combustor plenum to the exhaust with a sinusoidal massflow variation up to 700 Hz. Pressure transducers in the plenum and the flame tube monitored the forced disturbances. A photomultiplier recorded the OH* chemiluminescence of the flame. For the agreed operating conditions frequency scans of these values were registered. Additionally images of the OH* chemiluminescence were taken at selected frequencies and evaluated in a statistical manner, to separate turbulent and periodic behavior. From the analysis of the pressure data, it can be concluded, that serious thermoacoustic feedback was not observed for both burners. However, burner 2 with the flame detached from the wall exhibited a higher fluctuation level as burner 1 with the wall attached flame. A resonant behavior was observed near the characteristic frequency of the sound room comprised of plenum, flame tube, and burner nozzle as connecting passage. The chemiluminescence images show different modes of spatial fluctuation for the burners and for burner 2 they also vary with the operating condition.

Behavior of an Oscillating Oil Squeeze Film

1986 ◽  
Vol 108 (4) ◽  
pp. 639-644 ◽  
Author(s):  
D. W. Parkins ◽  
J. H. Woollam
Keyword(s):  
Film Thickness ◽  
Lower Surface ◽  
Squeeze Film ◽  
Oil Film ◽  
Pressure Transducers ◽  
Experimental Apparatus ◽  
Computer Controlled ◽  
Oscillatory Cycle ◽  
Steady Force ◽  
Oil Film Pressure

This paper records observations of the behavior of an oil film subject to an oscillatory squeeze motion of its containing surfaces. In the experimental apparatus, the square upper surface oscillated at a frequency within the range 5–45 Hz and contained two pressure transducers. A fixed transparent lower surface facilitated viewing of cavitation patterns and their position relative to the pressure transducers. A computer controlled technique enabled these patterns to be photographed at any selected point in the oscillatory cycle, and synchronized with the corresponding instantaneous oil film pressure and thickness. The effect is given of vibratory amplitude, frequency and initial oil film thickness upon the steady force generated by the oscillatory squeeze motion. A previously identified cavitation regime has been shown to be more complex than hitherto supposed. Four sub-regimes have been tentatively identified. Their characteristics are described, together with photographs of typical sequences of cavitation patterns in each subregime, at identified times in the pressure and film thickness cycle. The effects of surrounding oil depth upon the vibratory amplitude at which cavitation first appears, is described. Descriptions are given of the sub-regime appearing at onset, and any changes thereto appearing with further increases in vibratory amplitude.

Investigation of the Response of an Air Blast Atomiser Combustion Chamber Configuration on Forced Modulation of Air Feed at Realistic Operating Conditions

2002 ◽  
Author(s):  
Christoph Hassa ◽  
Johannes Heinze ◽  
Klaus Stursberg
Keyword(s):  
Combustion Chamber ◽  
Liquid Fuel ◽  
Aircraft Engine ◽  
Operating Conditions ◽  
Pressure Transducers ◽  
Flame Tube ◽  
Acoustic Feedback ◽  
Elevated Pressures ◽  
Periodic Behaviour ◽  
Burner Nozzle

DLR investigated forced combustion oscillations of two liquid fuel burners in a research combustion chamber at elevated pressures simulating idle conditions of aircraft engine combustors. The work was performed in collaboration with MTU Munich. An existing combustion chamber with optical access, capable to operate up to 20 bar, was upgraded with an air flow pulsator, that bypasses air from the combustor plenum to the exhaust with a sinusoidal massflow variation up to 700 Hz. Pressure transducers in the plenum and the flame tube monitored the forced disturbances. A photomultiplier recorded the OH* chemiluminescence of the flame. For the agreed operating conditions frequency scans of these values were registered. Additionally images of the OH* chemiluminescence were taken at selected frequencies and evaluated in a statistical manner, to separate turbulent and periodic behaviour. From the analysis of the pressure data, it can be concluded, that serious thermo-acoustic feedback was not observed for both burners. However burner 2 with the flame detached from the wall exhibited a higher fluctuation level as burner 1 with the wall attached flame. A resonant behaviour was observed near the characteristic frequency of the sound room comprised of plenum, flame tube and burner nozzle as connecting passage. The chemiluminescence images show different modes of spatial fluctuation for the burners and for burner 2 they also vary with the operating condition.

scholarly journals Optimal Tuner Selection for Kalman Filter-Based Aircraft Engine Performance Estimation

2009 ◽  
Vol 132 (3) ◽  
Author(s):  
Donald L. Simon ◽  
Sanjay Garg
Keyword(s):  
Kalman Filter ◽  
Estimation Error ◽  
Engine Performance ◽  
Aircraft Engine ◽  
Operating Conditions ◽  
Performance Estimation ◽  
Experimental Simulation ◽  
Tuning Parameter ◽  
Estimation Accuracy ◽  
On Line

A linear point design methodology for minimizing the error in on-line Kalman filter-based aircraft engine performance estimation applications is presented. This technique specifically addresses the underdetermined estimation problem, where there are more unknown parameters than available sensor measurements. A systematic approach is applied to produce a model tuning parameter vector of appropriate dimension to enable estimation by a Kalman filter, while minimizing the estimation error in the parameters of interest. Tuning parameter selection is performed using a multivariable iterative search routine that seeks to minimize the theoretical mean-squared estimation error. This paper derives theoretical Kalman filter estimation error bias and variance values at steady-state operating conditions, and presents the tuner selection routine applied to minimize these values. Results from the application of the technique to an aircraft engine simulation are presented and compared with the conventional approach of tuner selection. Experimental simulation results are found to be in agreement with theoretical predictions. The new methodology is shown to yield a significant improvement in on-line engine performance estimation accuracy.

Hysteresis loss of ultra-large off-the-road tire rubber compounds based on operating conditions at mine sites

2021 ◽  
pp. 095440702110155
Author(s):  
Shaosen Ma ◽  
Guangping Huang ◽  
Khaled Obaia ◽  
Soon Won Moon ◽  
Wei Victor Liu
Keyword(s):  
Large Strain ◽  
Tensile Tests ◽  
Operating Conditions ◽  
Hysteresis Loss ◽  
Strain Rates ◽  
Test Results ◽  
Tire Rubber ◽  
The Road ◽  
Rubber Compounds ◽  
Mine Sites

The objective of this study is to investigate the hysteresis loss of ultra-large off-the-road (OTR) tire rubber compounds based on typical operating conditions at mine sites. Cyclic tensile tests were conducted on tread and sidewall compounds at six strain levels ranging from 10% to 100%, eight strain rates from 10% to 500% s−1 and 14 rubber temperatures from −30°C to 100°C. The test results showed that a large strain level (e.g. 100%) increased the hysteresis loss of tire rubber compounds considerably. Hysteresis loss of tire rubber compounds increased with a rise of strain rates, and the increasing rates became greater at large strain levels (e.g. 100%). Moreover, a rise of rubber temperatures caused a decrease in hysteresis loss; however, the decrease became less significant when the rubber temperatures were above 10°C. Compared with tread compounds, sidewall compounds showed greater hysteresis loss values and more rapid increases in hysteresis loss with the rising strain rate.

scholarly journals Methodology for Selecting the Operating Conditions of a Vibration Generator Used in the Hot-Dip Galvanizing Process

Materials ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 2042
Author(s):  
Wojciech Kacalak ◽  
Igor Maciejewski ◽  
Dariusz Lipiński ◽  
Błażej Bałasz
Keyword(s):  
Simulation Model ◽  
Asynchronous Motor ◽  
Experimental Tests ◽  
Suspension System ◽  
Operating Conditions ◽  
Test Results ◽  
Forced Simulation

A simulation model and the results of experimental tests of a vibration generator in applications for the hot-dip galvanizing process are presented. The parameters of the work of the asynchronous motor forcing the system vibrations were determined, as well as the degree of unbalance enabling the vibrations of galvanized elements weighing up to 500 kg to be forced. Simulation and experimental tests of the designed and then constructed vibration generator were carried out at different intensities of the unbalanced rotating mass of the motor. Based on the obtained test results, the generator operating conditions were determined at which the highest values of the amplitude of vibrations transmitted through the suspension system to the galvanized elements were obtained.

Emission Reduction of Fuel Staged Aircraft Engine Combustor Using an Additional Premixed Fuel Nozzle

2012 ◽  
Author(s):  
Takeshi Yamamoto ◽  
Kazuo Shimodaira ◽  
Seiji Yoshida ◽  
Yoji Kurosawa
Keyword(s):  
Pressure Ratio ◽  
Aircraft Engine ◽  
Test Results ◽  
Drastic Reduction ◽  
Fuel Nozzle ◽  
Conducting Research ◽  
Japan Aerospace Exploration Agency ◽  
Co Emission ◽  
Fuel Burner ◽  
Additional Fuel

The Japan Aerospace Exploration Agency (JAXA) is conducting research and development on aircraft engine technologies to reduce environmental impact for the TechCLEAN project. As a part of the project, combustion technologies have been developed with an aggressive target that is an 80% reduction over the NOx threshold of the ICAO CAEP/4 standard. A staged fuel nozzle with a pilot mixer and a main mixer was developed and tested using a single-sector combustor under the target engine’s LTO cycle conditions with a rated output of 40 kN and an overall pressure ratio of 25.8. The test results showed a 77% reduction over the CAEP/4 NOx standard. A reduction in smoke was found under a higher thrust condition than the 30% MTO condition, and a reduction in CO emission was found under a lower thrust condition than the 85% MTO condition. In the present study, an additional fuel burner was designed and tested with the staged fuel nozzle in a single-sector combustor to control emissions. The test results show that the combustor enables an 82% reduction in NOx emissions relative to the ICAO CAEP/4 standard and a drastic reduction in smoke and CO emissions.

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