Download or read book Preliminary Investigation of the Dynamic Force Response Coefficients for Squeeze Film Bearing Dampers written by and published by . This book was released on 1974 with total page 97 pages. Available in PDF, EPUB and Kindle. Book excerpt: An experimental study of the hydrodynamic force response of a squeeze film bearing damper with end seals was carried out. Measurements of the pressure distribution about a journal constrained to more in a circular orbit were made for the journal orbit centered in the annular clearance and offset from the center of the annular clearance. The effects of cyclic flow in a radial inlet were studied for the case of the journal orbit centered in the annular clearance.
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1995 with total page 704 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book An Investigation Into Squeeze film Dampers written by and published by . This book was released on 1981 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Rotordynamics of Turbomachinery written by John M. Vance and published by John Wiley & Sons. This book was released on 1991-01-16 with total page 404 pages. Available in PDF, EPUB and Kindle. Book excerpt: Describes the rotordynamic considerations that are important to the successful design or troubleshooting of a turbomachine. Shows how bearing design, fluid seals, and rotor geometry affect rotordynamic behavior (vibration, shaft whirling, bearing loads, and critical speeds), and describes two successful computational methods for rotordynamic analysis in terms that can be understood by practicing engineers. Gives descriptive accounts of the state of the art in several areas of the field and presents important mathematical or computational concepts, describing equations and formulas in physical terms for better understanding. Also offers tips for troubleshooting unstable machines and provides practical interpretations of vibration measurements.
Download or read book Performance of an Open Ends Squeeze Film Damper Operating with Large Amplitude Orbital Motions written by Sung Hwa Jeung and published by . This book was released on 2014 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Squeeze Film Dampers (SFDs) aid to suppress rotor vibrations and enhance the stability of high-speed rotor-bearing systems. A SFD is a simple oil lubricated film between a stationary housing and a precessing (whirling) journal. Aircraft engines use SFDs as the only means to provide damping to otherwise rigid ball bearing supports. This thesis presents experimental results for the dynamic forced performance of a test open ends SFD operating with large amplitude whirl motions, centered and off centered within the bearing clearance. The test rig comprises of an elastically supported bearing with a damper section having two parallel film lands separated by a feed groove. A film land is 25.4 mm long, with diameter 127 mm and nominal radial clearance c=0.251 mm. Two orthogonally placed shakers apply dynamic loads on the bearing to induce circular orbit motions at prescribed whirl frequencies. A static loader, 45° away from each shaker, pulls the bearing to a static eccentric position. Circular orbit tests were performed (10-100 Hz frequency range) for eight increasing orbit amplitudes (r=0.08c to ~0.71c) and under four static eccentricities (e[subscript s]=0.0c to ~0.76c). An identification method estimates the test damper force coefficients from transfer functions in the frequency domain. The analysis shows that the SFD damping force coefficients increase with the static eccentricity (e[subscript s]) increase. On the other hand, the damper inertia coefficients decrease as the orbit amplitude (r) becomes large and also increase modestly with the static eccentricity (e[subscript s]). Predictions from a physical model show good agreement with the test dynamic force coefficients. The accuracy of the linearized SFD force coefficients (K, C, M)[subscript SFD] is evaluated from comparing the differences in mechanical work performed by actual and linear SFD reaction forces. The difference in mechanical work (E[subscript diff]) increases with increasing static eccentricity (e[subscript s]) and orbit amplitude (r). However, for most test conditions (r/c≤0.4,e[subscript s]/c≤0.25), E[subscript diff] is less than ~5%, thus showing the linearized SFD force coefficients represent well the forced response of the actual test SFD system. The test and predicted force coefficients as well as the analysis of the pressure fields contribute to a better understanding of the kinetics of SFDs operating with moderate tolarge amplitude size whirl motions, centered and off-centered. The electronic version of this dissertation is accessible from http://hdl.handle.net/1969.1/151648
Download or read book Study of Hydrodynamic Force Coefficients for a Grooved Squeeze Film Damper written by Jia Xin Zhang and published by . This book was released on 1994 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book ASME Technical Papers written by and published by . This book was released on 1999 with total page 556 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book EIES Research Report written by University of Florida. Engineering and Industrial Experiment Station and published by . This book was released on 1977 with total page 238 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Investigation of an Aero engine Squeeze film Damper written by Muzaffer Doğan and published by . This book was released on 1983 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Nonlinear analysis of squeeze film dampers design and application for aircraft engines written by Edgar J. Gunter and published by . This book was released on 1976 with total page 100 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Experimental Dynamic Forced Performance of a Centrally Grooved End Sealed Squeeze Film Damper written by Lady Paola Mahecha Mojica and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Squeeze film dampers (SFDs) provide viscous damping to attenuate excessive vibrations and enhance system stability in turbomachinery. SFDs are of special importance in aircraft engines which use rolling element support bearings that, by themselves, do not provide enough damping to ensure safe operation. A modular test rig capable of simulating actual operating conditions in aircraft jet engines is used to test two centrally grooved, end sealed, SFDs. Both SFDs have diameter D and nominal radial clearance c and consist of two parallel squeeze film lands separated by a deep circumferential groove of length LG and depth dG. A short length damper with film land lengths L and a long damper with land lengths 2L are tested. Piston rings seal the damper lands. An ISO VG2 lubricant is supplied to the SFD via three radial holes that discharge lubricant into the central groove. The lubricant passes through the damper lands and across the piston ring seals to finally exit the damper at ambient pressure. Circular orbit tests of amplitude ~0.5c and for static eccentricities varying from 0 to ~0.36c are conducted on the two sealed dampers. The instrumental variable filter method (IVFM) serves to identify the SFD dynamic force coefficients. The parameter identification range is 50Hz to 210Hz for the short damper and 110Hz to 250Hz for the long damper. Large amplitude dynamic pressures measured in the central groove demonstrate that the central groove does not divide the damper in two separate film lands, but the lubricant in the groove interacts with the squeeze film lands, hence contributing significantly to the SFD forced response. Dynamic pressures in the film lands and in the central groove reveal that both dampers operate free of air ingestion or cavitation for the tested static eccentricities and amplitudes of motion. Comparisons to test results for the same SFD configurations but with open ends demonstrate the effectiveness of the end seals on increasing the direct damping coefficients. For the sealed ends short length damper, the added mass coefficients are ~2 times larger and the damping coefficients are ~3.8 times larger than the respective coefficients of the open ends long damper. For the sealed ends long damper, the damping coefficients are ~2.8 times, and the added mass coefficients are ~3.1 times larger than coefficients from the open ends configuration. The identified SFD direct stiffness coefficients are nearly zero except at the maximum static eccentricity for the long damper. Predictions from a novel computational model that include the effects of the central groove, the lubricant feed holes and the end seals are in excellent agreement with results from the short length damper. For the long damper, the predicted damping coefficients are in good agreement with the test results, while the added mass coefficients are under predicted by ~25 percent. Experimental results from the two sealed SFD configurations lead to a better understanding of the effects of end seals as well as central feed groves on the SFD forced performance. The results presented in this thesis will help improve the effectiveness of SFDs aircraft jet engines.
Download or read book Performance of a Short Open End Squeeze Film Damper With Feed Holes written by Gary Daniel Bradley and published by . This book was released on 2013 with total page 116 pages. Available in PDF, EPUB and Kindle. Book excerpt: With increasing rotor flexibility and shaft speeds, turbomachinery undergoes large dynamic loads and displacements. Squeeze film dampers (SFDs) are a type of fluid film bearing used in rotating machinery to attenuate rotor vibration, provide mechanical isolation, and/or to tune the placement of system critical speeds. Industry has a keen interest in designing SFDs that are small, lightweight, and mechanically simple. To achieve this, one must have a full understanding of how various design features affect the SFD forced performance. This thesis presents a comprehensive analysis, experimental and theoretical, of a short (L=25.4 mm) open ends SFD design incorporating three lubricant feed holes (without a circumferential feed groove). The damper radial clearance (c=127 [mu]m), L/D ratio (0.2), and lubricant (ISO VG2) have similar dimensions and properties as in actual SFDs for aircraft engine applications. The work presents the identification of experimental force coefficients (K, C, M) from a 2-DOF system model for circular and elliptical orbit tests over the frequency range [omega]=10-250Hz. The whirl amplitudes range from r=0.05c-0.6c, while the static eccentricity ranges from eS=0-0.5c. Analysis of the measured film land pressures evidence that the deep end grooves (provisions for installation of end seals) contribute to the generation of dynamic pressures in an almost purely inertial fashion. Film land dynamic pressures show both viscous and inertial effects. Experimental pressure traces show the occurrence of significant air ingestion for orbits with amplitudes r>0.4c, and lubricant vapor cavitation when pressures drop to the lubricant saturation pressure (PSAT~0 bar). Identified force coefficients show the damper configuration offers direct damping coefficients that are more sensitive to increases in static eccentricity (eS) than to increases in amplitude of whirl (r). On the other hand, SFD inertia coefficients are more sensitive to increases in the amplitude of whirl than to increases in static eccentricity. For small amplitude motions, the added or virtual mass of the damper is as large as 27% of the bearing cartridge mass (MBC=15.15 kg). The identified force coefficients are shown to be insensitive to the orbit type (circular or elliptical) and the number of open feed holes (3, 2, or 1). Comparisons of damping coefficients between a damper employing a circumferential feed groove1 and the current damper employing feed holes (no groove), show that both dampers offer similar damping coefficients, irrespective of the orbit amplitude or static eccentricity. On the other hand, the grooved damper shows much larger inertia force coefficients, at least ~60% more. Predictions from a physics based model agree well with the experimental damping coefficients, however for large orbit motion, over predict inertia coefficients due to the model neglecting convective inertia effects. Credence is given to the validity of the linearized force coefficients by comparing the actual dissipated energy to the estimated dissipated energy derived from the identified force coefficients. The percent difference is below 25% for all test conditions, and in fact is shown to be less than 5% for certain combinations of orbit amplitude (r), static eccentricity (eS), and whirl frequency ([omega]). The electronic version of this dissertation is accessible from http://hdl.handle.net/1969.1/151179
Download or read book Government Reports Annual Index written by and published by . This book was released on 1975 with total page 882 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Influence of Oil squeeze film Damping on Steady state Response of Flexible Rotor Operating to Supercritical Speeds written by Robert E. Cunningham and published by . This book was released on 1977 with total page 52 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Journal of Engineering for Power written by and published by . This book was released on 1983 with total page 976 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Paper written by and published by . This book was released on 1987 with total page 614 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Journal of Lubrication Technology written by and published by . This book was released on 1980 with total page 598 pages. Available in PDF, EPUB and Kindle. Book excerpt:
