Florida Institute of TechnologyFlorida Institute of Technology

Department of Mechanical and Aerospace Department of Mechanical and Aerospace EngineeringEngineering

Dr. Daniel KirkDr. Daniel KirkDr. Hector GutierrezDr. Hector Gutierrez

Tank Fluid Dynamics TeamTank Fluid Dynamics Team

NASA Kennedy Space CenterNASA Kennedy Space Center

Expendable Launch Vehicle / Mission Expendable Launch Vehicle / Mission Analysis BranchAnalysis Branch

Paul SchallhornPaul SchallhornLaurie WallsLaurie Walls

Mike CampbellMike CampbellSukhdeep ChaseSukhdeep Chase

Modeling Slosh Dynamics in Cryogenic Fuel Tanks under Microgravity

•• Fuel in a multiFuel in a multi--stage rocket experiences stage rocket experiences cyclic changes in temperature due to solar cyclic changes in temperature due to solar heating heating pressure relief vents are needed pressure relief vents are needed

•• Low gravity at high altitudes + orbital Low gravity at high altitudes + orbital maneuvers may lead to liquid slosh reaching maneuvers may lead to liquid slosh reaching the pressure relief ventsthe pressure relief vents

•• Loss of liquid mass Loss of liquid mass dynamic instability dynamic instability possible mission failure due to loss of possible mission failure due to loss of

proper orbital altitude proper orbital altitude

•• Correct prediction of the slosh dynamics is Correct prediction of the slosh dynamics is critical for spacecraft stability and controlcritical for spacecraft stability and control

•• Clear Acrylic Tank: 10Clear Acrylic Tank: 10”” OD x OD x 9.59.5”” ID x 9.5ID x 9.5”” H H

•• Flat End / Spherical Dome Flat End / Spherical Dome ConfigurationConfiguration

•• Mounted on 1Mounted on 1--DOF computerDOF computer--controlled vibration table controlled vibration table

•• Tank moves according to userTank moves according to user--specified amplitude and frequencyspecified amplitude and frequency

•• Orthogonal cameras are used to Orthogonal cameras are used to record slosh data record slosh data

1 DOF motion

EXPERIMENTAL SLOSH IMAGES: INERTIAL FRAME

EXAMPLES OF MATLAB IMAGE EXTRACTION

Tank images are used to generate a 3D model Tank images are used to generate a 3D model of liquid slosh (position on tankof liquid slosh (position on tank’’s wall, s wall, maximum height, and percent of wall maximum height, and percent of wall coveragecoverage))

Results are mapped over varying combinations of amplitude and Results are mapped over varying combinations of amplitude and frequency to determine turbulent and steadyfrequency to determine turbulent and steady--state slosh patternsstate slosh patterns

•• Development of experimental framework for characterization of Development of experimental framework for characterization of

liquid slosh in microgravityliquid slosh in microgravity

•• MultiMulti--axis motion controlaxis motion control

•• MultiMulti--axis vision system and instrumentationaxis vision system and instrumentation

•• Development of a CFD model that can predict liquid sloshing for Development of a CFD model that can predict liquid sloshing for

varying parameters such as tank geometry, liquid density, and varying parameters such as tank geometry, liquid density, and

gravitygravity

•• Acquisition of multiAcquisition of multi--DOF slosh data in microgravity that can be DOF slosh data in microgravity that can be

shared by researchers from NASA, academia, and industryshared by researchers from NASA, academia, and industry

OBJECTIVES

•• At 24,000ft the DC9 begins 8,000ft At 24,000ft the DC9 begins 8,000ft climb at 1.8gclimb at 1.8g’’s. s. •• At 31,000ft At 31,000ft start Zerostart Zero--G climbG climb•• Zero gravity ~ 20Zero gravity ~ 20--25 seconds25 seconds•• After weightlessness, the DC9 After weightlessness, the DC9 cruises back down to 24,000ft.cruises back down to 24,000ft.•• Typically 40 parabolas per day Typically 40 parabolas per day ––800 to 1000 seconds of total test 800 to 1000 seconds of total test time.time.•• Over a 5 day test period: 66.7Over a 5 day test period: 66.7--83.3 83.3 minutes of test dataminutes of test data

9

SLOSH EXPERIMENT - NASA’S ZERO-GRAVITY AIRCRAFTSUMMER 2008

Two independent Two independent orthogonal axes of orthogonal axes of motion (72motion (72”” and 41and 41””travel)travel)

Three cameras record Three cameras record liquid slosh relative to liquid slosh relative to tanktank’’s frame (X, Y, Z s frame (X, Y, Z axes)axes)

Tanks of various Tanks of various geometries can be tested geometries can be tested (16(16”” Sphere, 10 x 10Sphere, 10 x 10””Cylinder, 20Cylinder, 20”” x 10x 10”” Pill)Pill)

Tank

Axial drive motorand lead screw assembly

Transverse drive motorand lead screw assembly

Path with controlled position, velocity and acceleration

2-DOF Slosh Experiment

4-DOF Zero-Gravity Slosh Experiment

Four independent degrees of freedom using 4-axis CNC motion controller

XY translation stageRotary stage in Z axisPivoting arm holding tank (top stage)

Arbitrary trajectories (position, velocity, acceleration) can be programmed on each DOF to simulate orbital maneuversAll experiments can be exactly programmed and played back as CNC code

4-DOF Zero-Gravity Slosh Experiment

PIVOT-ARMMOTOR

SLOSH TANK

x

y

4 Independent Programmable Axes of Motion with Encoder feedbackData acquisition PC, sensors and cameras attached to top stage

θz

PIVOT-ARMROTARY STAGE

X-YMOTORS

θy

Instrumentation

Accurate encoder-based measurements of position, velocity and acceleration of each DOFTwo tri-axial accelerometers in slosh tankThree orthogonal cameras attached to tank’s frame3-DOF acceleration of plane relative to ground available for simultaneous recordingAll data acquisition synchronized by hardware trigger

ConclusionProblem of great relevance to NASA and Aerospace IndustryNovel experimental framework for characterization of slosh dynamicsScaling to full size fuel tanks achieved by use of non-dimensional numbers and scaling lawsData to be obtained will be used by NASA and other researchers to benchmark:

Analytical slosh modelsComputational (CFD) slosh models and simulationsExperiment-based Design tools to model slosh