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Stiffler, A. K.

Publications and source records attributed to Stiffler, A. K..

8 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1979

Amplitude effects on the dynamic performance of hydrostatic gas thrust bearings

A strip gas film bearing with inherently compensated inlets is analyzed to determine the effect of disturbance amplitude on its dynamic performance. The governing Reynolds' equation is solved using finite-difference techniques. The time dependent load capacity is represented by a Fourier series up to and including the third harmonics. For the range of amplitudes investigated the linear stiffness was independent of the amplitude, and the linear damping was inversely proportional to (1 - epsilon-squared) to the 1.5 power where epsilon is the amplitude relative to the film thickness.

Stiffler, A. K.↗
NASA NTRS1978

Dynamics of gas-thrust bearings

Computer program calculates load coefficients, up to third harmonic, for hydrostatic gas thrust bearings. Program is useful in identification of industrial situations where gas-thrust bearings have potential applications.

Stiffler, A. K.↗
NASA NTRS1977

A pressurized gas squeeze film journal damper

A lumped parameter model is developed to determine the stiffness and damping characteristics of inherently compensated gas film bearings. The model relies on the average static pressure over a one dimensional strip bearing. Results of the model are compared with known computer solutions for the distributed strip and a two dimensional square bearing. The results for the stiffness agree well with the computer solutions although the model proved to be inadequate for predicting the film damping.

Stiffler, A. K.↗
NASA NTRS1975

Amplitude effects on the dynamic performance of a hydrostatic gas thrust bearing

The Reynolds' equation is applied to a strip gas thrust bearing to analyze amplitude disturbance effects on its dynamic performance. The Reynolds' equation is numerically approximated using finite difference techniques. The time dependent load carrying capacity is represented by a Fourier series up to and including the third harmonics. Design curves for the load capacity and the linear stiffness and damping are presented as a function of inlet location, restrictor coefficient, supply pressure, amplitude of oscillation, and squeeze number. For the range of amplitudes investigated the dimensionless load capacity, stiffness and damping does not exhibit an appreciable change in magnitude; thus, only one design curve is needed to represent each relationship. A design methodology is presented.

Stiffler, A. K.↗
NASA NTRS1975

Studies on the dynamic characteristics of gas film bearings and dampers

The dynamic characteristics of inherently compensated gas film bearings have been investigated for small excursion ratios. Both circular and rectangular cases have been solved for the stiffness and damping as a function of supply pressure, restrictor coefficient, and squeeze number. The effect of disturbance amplitude has been studied for the inherently compensated strip. Analytical solutions for the simple gas film damper problem have established the effect of disturbance amplitude at low squeeze numbers. These results are applicable to pressurized bearings as limiting case of the restrictor coefficient.

Stiffler, A. K.↗
NASA NTRS1975

Squeeze film dampers - Amplitude effects at low squeeze numbers

Gaseous squeeze film dampers are analyzed to determine the effect of periodic disturbance amplitude on the dynamic performance. Both circular and rectangular parallel surfaces are investigated. A solution of the nonlinear Reynolds equation is obtained by expanding the pressure in powers of the squeeze number, retaining up to and including terms of the order of the square of the squeeze number. The time dependent load characteristics are found. The effect of disturbance amplitude on the film stiffness and damping is given.

Sadd, M. H.↗
NASA NTRS1975

Signal transit velocities in a turbulent plane jet

A turbulent jet is perturbed transverse to the flow direction by periodic pressure gradients near the nozzle exit. Transit velocities are defined in terms of the measured signal time delay for stations 8, 12, 16 nozzle widths downstream of the nozzle exit. Excitation frequencies to 800 cps are considered. Transit velocities are found to be much less than the jet centerline velocity. The results are related to the convection velocity of turbulence.

Stiffler, A. K.↗