Bubble behaviors in a slowly rotating helium dewar in a Gravity Probe-B spacecraft experiment

Hung, R. J.; Tsao, Y. D.; Leslie, F. W.; Hong, Baoyu

doi:10.2514/3.26049

Cited by 69 publications

(9 citation statements)

References 8 publications

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“…The initial conditions for the liquid-vapour interface profiles were adopted from the steady state formulations for a rotating Dewar developed by Hung and Leslie 2 " and by Hung el a/. 7 . In response to a lateral impulse, the sloshing dynamics are responsible for the excitation of sloshing waves of higher frequency modes for Dewars with higher rotating speeds.…”

Section: Discussionmentioning

confidence: 99%

“…In the computation of the sloshing reaction forces, and the moments, viscous stress and angular momentum acting on the container wall of the spacecraft, one must consider those forces and moments in the inertial frame rather than in the non-inertial frame 16 1S . For the purpose of solving sloshing dynamic problems of liquid systems in orbital spacecraft under a microgravity environment, one must solve the governing equations' 7 accompanied by a set of initial and boundary conditions. A detailed illustration of these initial and boundary conditions concerning the sloshing dynamics of fluid systems in microgravity was precisely given in work by Hung and p ar) i6.i7 w j ne com p u tational algorithm applicable to cryogenic fluid management under microgravity has also been given earlier 17 " 19 .…”

Section: Non-inertial Frame Mathematical Formulation Of Fundamental Ementioning

confidence: 99%

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Effect of baffle on slosh reaction forces in rotating liquid helium subjected to a lateral impulse in microgravity

Hung

Long

1995

Cryogenics

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Sloshing dynamics within a partially filled rotating Dewar of superfluid He II are investigated in response to a lateral impulse. The study investigates several factors, including how the rotating bubble of superfluid He II reacts to the impulse in microgravity, how the amplitudes of slosh reaction forces act on the Dewar with various rotating speeds, how the frequencies of the sloshing modes excited differ in terms of differences in rotating speeds, and how the sloshing dynamics differ with and without a baffle. The numerical computation of sloshing dynamics is based on the non-inertial frame spacecraft-bound co-ordinate. Results of the simulations are illustrated.

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Section: Discussionmentioning

confidence: 99%

Section: Non-inertial Frame Mathematical Formulation Of Fundamental Ementioning

confidence: 99%

Effect of baffle on slosh reaction forces in rotating liquid helium subjected to a lateral impulse in microgravity

Hung

Long

1995

Cryogenics

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“…17 The equilibrium configurations of the helium bubble in a rotating dewar was studied. 5 They are relevant to the questions of fluid behavior in a microgravity environment raised by design and operational considerations for the GP-B experiment. For a spacecraft operating as designed, spacecraft drag will be balanced by the helium propulsion system.…”

mentioning

confidence: 99%

“…6 -14 At the interface between the liquid and the gaseous fluids, both the kinematic surface boundary condition and the interface stress conditions for components tangential and normal to the interface were applied. The initial condition of bubble profiles was adopted from the steady-state formulations, in which the computer algorithms have been developed by Hung and Leslie, 4 and Hung et al 5 in a rotating cylinder tank, and, also, by Hung et al 5 -15 in the coordinate of the GP-B Spacecraft. 2 Some of the steady-state formulations of bubble shapes, in particular, for bubbles intersecting the top wall of the cylinder, were compared with the available experiments carried out by Leslie 7 in a free-falling aircraft (KC-135).…”

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confidence: 99%

Response of gravity level fluctuations on the Gravity Probe-B spacecraft propellant system

Hung

Lee

Leslie

1991

Journal of Propulsion and Power

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The dynamical behavior of fluids, in particular, the effect of surface tension on partially filled fluids in a rotating dewar under microgravity environment, has been investigated. Results show that there is a group of wave trains, both in longitudinal and transverse modes, with various frequencies and wavelengths of slosh waves generated by the restoring force field of gravity jitters and centrifugal forces in this study. The longest wave periods of slosh waves, either the longitudinal or transverse modes, are responsible for the production of wave modes with the highest ratio of maximum wave amplitude to wavelength. Also, the lower frequency slosh waves are the wave modes with higher wave energy than that of the higher frequency slosh waves. Nomenclature a = radius of the circular cylinder f 0 = frequency of gravity jitters, defined by Eq. (13) g = gravitational acceleration g B = background gravity environment, defined by Eq. (13) go = normal Earth gravitational acceleration, 9.81 m/s 2 L = length of the cylinder Max(A/\) = ratio of maximum wave amplitude to wavelength n -unit vector normal to the interface P = pressure r = cylindrical coordinate along radial direction t = time u = velocity component along radial direction v = velocity component along axial direction z = cylindrical coordinate along axial direction 8 = Dirac delta function ( = viscous coefficient of the second kind 17 = profile of interface between gaseous and liquid fluids, defined by Eq. (7) 0 = cylindrical coordinate along circumferential direction fi = viscous coefficient of the first kind v = kinematic viscosity coefficient p = density <7 = surface tension of the interface T fJ = viscous stress tensor = tangent of interface, defined by Eq. (12) CD = rotating angular velocity of cylinder Subscripts G = gaseous fluid L = liquid fluid IntroductionT HE Gravity Probe-B (GP-B) Spacecraft (see Fig. 1) is designed to test the general theory of relativity through a long-term (1 year) monitoring of the procession of a set of gyros in free-fall around the Earth. 1 -2 Extraneous forces on these gyros must be kept at very low levels, corresponding to an acceleration of 10~1 0 g () (g 0 = 9.81 m/s 2 ) or less. This will require a drag-free (to 10 ~1 0 g 0 ) control system using a proof mass similar to the experiment gyros as its sensing element. The experiment uses superconducting sensors for gyro readout and maintains very low temperature for mechanical stability. The approaches to both cooling and control involve the use of superfluid liquid helium. The boil-off from the liquid helium dewar (Fig. 2) will be used as a propellant to maintain the attitude control and drag-free operation of the spacecraft. The requirement for an operational lifetime approaching one year means that a large quantity of liquid helium must be used, and that it will be gradually depleted over the lifetime of the experiment. This varying amount of liquid helium gives rise to the possibility of several problems that could degrade the GP-B experiment. The potential problems...

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“…18 " 22 It may be shown that with suitable electrode configurations, in the AES approach the liquids to be controlled may be pure dielectrics.…”

mentioning

confidence: 99%

Passive and active stabilization of liquid bridges in low gravity

Marston

Thiessen

Marr-Lyon

et al. 2001

2001 Conference and Exhibit on International Space Station Utilization

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Bubble behaviors in a slowly rotating helium dewar in a Gravity Probe-B spacecraft experiment

Cited by 69 publications

References 8 publications

Effect of baffle on slosh reaction forces in rotating liquid helium subjected to a lateral impulse in microgravity

Effect of baffle on slosh reaction forces in rotating liquid helium subjected to a lateral impulse in microgravity

Response of gravity level fluctuations on the Gravity Probe-B spacecraft propellant system

Passive and active stabilization of liquid bridges in low gravity

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