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Kirk, R. G.

Publications and source records attributed to Kirk, R. G..

13 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1993

Active magnetic bearings applied to industrial compressors

The design and shop test results are given for a high-speed eight-stage centrifugal compressor supported by active magnetic bearings. A brief summary of the basic operation of active magnetic bearings and the required rotor dynamics analysis are presented with specific attention given to design considerations for optimum rotor stability. The concerns for retrofits of magnetic bearings in existing machinery are discussed with supporting analysis of a four-stage centrifugal compressor. The current status of industrial machinery in North America using this new support system is presented and recommendations are given on design and analysis requirements for successful machinery operation of either retrofit or new design turbomachinery.

Kirk, R. G.↗
NASA NTRS1988

Oceanographic wide field sensor

The Oceanographic Wide Field Sensor (SeaWiFS) science project will provide measurements of ocean color from space to which will support research into: (1) the character of ocean physical and biological processes; (2) to assess the global oceanic biomass; and (3) to better understand the role of oceanic processes in modulating the Earth's biogeochemical cycles, including the CO2 cycle as it is affected by fossil fuel combustion. The present work extends previous work to study the feasibility of an ocean color mission using the proposed compact Wide-Field Sensor (SeaWiFS) and the EOSAT Corporation's LANDSAT-6 satellite. A Phase A study was conducted which defines a NASA Facility Data System and accompanying Science Program for the EOSAT Company's commercial ocean color instrument called SeaWiFS to be launched on board LANDSAT-6 in 1991.

Kirk, R. G.↗
NASA NTRS1985

Full load shop testing of 18,000-hp gas turbine driven centrifugal compressor for offshore platform service: Evaluation of rotor dynamics performance

The results for in-plant full load testing of a 13.4 MW (18000 HP) gas turbine driven centrifugal compressor are presented and compared to analytical predictions of compressor rotor stability. Unique problems from both oil seals and labyrinth gas seals were encountered during the testing. The successful resolution of these problems are summarized.

Kirk, R. G.↗
NASA NTRS1985

Active magnetic bearings for optimum turbomachinery design

The design and shop test results are given for a high speed eight stage centrifugal compressor supported by active magnetic bearings. A brief summary of the rotor dynamics analysis is presented with specific attention given to design considerations for optimum rotor stability. The concerns for retrofit of magnetic bearings in existing machinery are discussed with supporting analysis of a four stage centrifugal compressor. Recommendations are given on design and analysis requirements for successful machinery operation of either retrofit or new design turbomachinery.

Hustak, J.↗
NASA NTRS1982

Instabilities of geared couplings: Theory and practice

The use of couplings for high speed turbocompressors or pumps is essential to transmit power from the driver. Typical couplings are either of the lubricated gear or dry diaphragm type design. Gear couplings have been the standard design for many years and recent advances in power and speed requirements have pushed the standard design criteria to the limit. Recent test stand and field data on continuous lube gear type couplings have forced a closer examination of design tolerances and concepts to avoid operational instabilities. Two types of mechanical instabilities are reviewed in this paper: (1) entrapped fluid, and (2) gear mesh instability resulting in spacer throw-out onset. Test stand results of these types of instabilities and other directly related problems are presented together with criteria for proper coupling design to avoid these conditions. An additional test case discussed shows the importance of proper material selection and processing and what can happen to an otherwise good design.

Kirk, R. G.↗
NASA NTRS1980

Analysis and identification of subsynchronous vibration for a high pressure parallel flow centrifugal compressor

The summary of a complete analytical design evaluation of an existing parallel flow compressor is presented and a field vibration problem that manifested itself as a subsynchronous vibration that tracked at approximately 2/3 of compressor speed is reviewed. The comparison of predicted and observed peak response speeds, frequency spectrum content, and the performance of the bearing-seal systems are presented as the events of the field problem are reviewed. Conclusions and recommendations are made as to the degree of accuracy of the analytical techniques used to evaluate the compressor design.

Kirk, R. G.↗
NASA NTRS1975

Stability and transient motion of a plain journal mounted in flexible damped supports

Results are presented for an extensive study of the influence of damped flexible supports on the stability-threshold speed of a symmetric rotor mounted in nonlinear fluid-film bearings. A stability analysis is conducted by applying the Routh criteria and calculating the damped eigenvalues of the system. Stability maps are given in dimensionless form for a range of support stiffness, damping, and mass ratios. The effect of rotor imbalance on the stability of rotor systems is examined, and it is shown that time transient orbits of shaft and support motions clearly indicate their dynamic behavior for both stable and unstable operating speeds. Simple design criteria are proposed for choosing the support stiffness and damping on the basis of rotor weight and journal clearance to promote optimum stability. It is concluded that the use of a flexible damped support system may increase the stability threshold of a plain journal bearing and that damper supports should promote smoother and quieter machine operation by suppressing oil whirl and attenuating unbalanced rotational forces.

Kirk, R. G.↗
NASA NTRS1973

Nonlinear transient analysis of multi-mass flexible rotors - theory and applications

The equations of motion necessary to compute the transient response of multi-mass flexible rotors are formulated to include unbalance, rotor acceleration, and flexible damped nonlinear bearing stations. A method of calculating the unbalance response of flexible rotors from a modified Myklestad-Prohl technique is discussed in connection with the method of solution for the transient response. Several special cases of simplified rotor-bearing systems are presented and analyzed for steady-state response, stability, and transient behavior. These simplified rotor models produce extensive design information necessary to insure stable performance to elastic mounted rotor-bearing systems under varying levels and forms of excitation. The nonlinear journal bearing force expressions derived from the short bearing approximation are utilized in the study of the stability and transient response of the floating bush squeeze damper support system. Both rigid and flexible rotor models are studied, and results indicate that the stability of flexible rotors supported by journal bearings can be greatly improved by the use of squeeze damper supports. Results from linearized stability studies of flexible rotors indicate that a tuned support system can greatly improve the performance of the units from the standpoint of unbalanced response and impact loading. Extensive stability and design charts may be readily produced for given rotor specifications by the computer codes presented in this analysis.

Kirk, R. G.↗
NASA NTRS1973

Transient response of rotor-bearing systems.

The equations of motion necessary to calculate the transient response of a multimass flexible rotor supported by nonlinear, damped bearings are derived from energy principles. Rotor excitation may be the result of imbalance, internal friction, rotor acceleration, nonlinear forces due to any number of bearing or seal stations, and gyroscopic couples developed from skewed disk effects. The method of solution for transient response simulation is discussed in detail and is based on extensive evaluation of numerical methods available for transient analysis. Examples of the application of transient response for the analysis of rotor bearing systems are presented and compared to actual machine performance. Recommendations for the use and extension of the present system simulation model are discussed.

Kirk, R. G.↗
NASA NTRS1972

Effect of support flexibilty and damping on the dynamic response of a single mass flexible rotor in elastic bearings

A steady state analysis of the shaft and the bearing housing motion was made by assuming synchronous precession of the system. The conditions under which the support system would act as a dynamic vibration absorber at the rotor critical speed were studied; plots of the rotor and support amplitudes, phase angles, and forces transmitted were evaluated by the computer, and the performance curves were automatically plotted by a CalComp plotter unit. Curves are presented on the optimization of the support housing characteristics to attenuate the rotor unbalance response over the entire rotor speed range. The complete transient motion including rotor unbalance was examined by integrating the equations of motion numerically using a modified fourth order Runge-Kutta procedure, and the resulting whirl orbits were plotted by the CalComp plotter unit. The results of the transient analysis are discussed with regards to the design optimization procedure derived from the steady-state analysis.

Kirk, R. G.↗
NASA NTRS1972

The effect of support flexibility and damping on the dynamic response of a single mass flexible rotor in elastic bearings

The dynamic unabalance response and transient motion of the single mass Jeffcott rotor in elastic bearings mounted on damped, flexible supports are discussed. A steady state analysis of the shaft and the bearing housing motion was made by assuming synchronous precession of the system. The conditions under which the support system would act as a dynamic vibration absorber at the rotor critical speed were studied. Plots of the rotor and support amplitudes, phase angles, and forces transmitted were evaluated by the computer and the performance curves were plotted by an automatic plotter unit. Curves are presented on the optimization of the support housing characteristics of attenuate the rotor synchronous unbalance response.

Kirk, R. G.↗