Models and experiments are developed to investigate how a small amount of gas can cause large rectified motion of a piston in a vibrated liquid-filled housing when piston drag depends on piston position so that damping is nonlinear even for viscous flow. Two bellows serve as surrogates for the upper and lower gas regions maintained by Bjerknes forces. Without the bellows, piston motion is highly damped. With the bellows, the piston, the liquid, and the two bellows move together so that almost no liquid is forced through the gaps between the piston and the housing. This Couette mode has low damping and a strong resonance: the piston and the liquid vibrate against the spring formed by the two bellows (like the pneumatic spring formed by the gas regions). Near this resonance, the piston motion becomes large, and the nonlinear damping produces a large rectified force that pushes the piston downward against its spring suspension. A recently developed model based on quasi-steady Stokes flow is applied to this system. A drift model is developed from the full model and used to determine the equilibrium piston position as a function of vibration amplitude and frequency. Corresponding experiments are performed for two different systems. In the two-spring system, the piston is suspended against gravity between upper and lower springs. In the spring-stop system, the piston is pushed up against a stop by a lower spring. Model and experimental results agree closely for both systems and for different bellows properties.
Gas-Induced Motion of a Piston in a Vibrated Liquid-Filled Housing
This paper has been authored by National Technology and Engineering Solutions of Sandia, LLC, under Contract No. DE-NA0003525 with the U.S. Department of Energy. The U.S. Government retains and the publisher, by accepting the article for publication, acknowledges that the U.S. Government retains a nonexclusive, paid-up, irrevocable, world-wide license to publish or reproduce the published form of this paper, or allow others to do so, for U.S. Government purposes.Contributed by the Fluids Engineering Division of ASME for publication in the JOURNAL OF FLUIDS ENGINEERING. Manuscript received August 28, 2018; final manuscript received January 28, 2019; published online March 25, 2019. Assoc. Editor: Wayne Strasser.
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Torczynski, J. R., O'Hern, T. J., Clausen, J. R., and Koehler, T. P. (March 25, 2019). "Gas-Induced Motion of a Piston in a Vibrated Liquid-Filled Housing." ASME. J. Fluids Eng. September 2019; 141(9): 091106. https://doi.org/10.1115/1.4042757
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