Freestream Behavior of Water in Microgravity NASA Student Flight Reduced Gravity Opportunities Program

Research Advisor: Dr. Eugene UngarStudent Lead: Timothy Havard

Christie Carlile, Geoff Meier, Samina Bhatia, Derek Peterson

California Space Grant Consortium, Department of Mechanical and Aerospace Engineering

BackgroundDesigning a non-contact urine collection device (UCD) for use in space has been a complicated engineering problem since the beginning of the space program. There has been little research done on urine stream breakup, in microgravity. The urine receptacle assembly (URA) was critical hardware designed to collect urine in missions after Apollo 8. However, the URA's design resulted in splashback resulting in contamination on and around the hardware. Now that NASA has decided to go back to the moon, a lightweight UCD is needed in the capsule. In order to improve the URA, and account for women astronauts, further study of urine freestream flow is required.

Program OverviewThe Reduced Gravity Program is a NASA university program that accepted 20 undergraduate teams nationwide to fly research projects on a Zero-G ® Aircraft. The aircraft simulates microgravity by flying parabolic trajectories. The project proposal was submitted in November, participants were selected in January and will fly in late March.

Results to DateSeveral ground tests have been preformed using preliminary hardware to determine baseline data for continued testing (see above). Flight Hardware is currently being assembled and will be used to do further ground testing as a control. The final stage of data collection will come when the apparatus is flown on the microgravity simulating aircraft.

Flight ApparatusThe flow through the simulated urethras is controlled using a piston powered by a DC motor. This motor is controlled using a LabView interface and which is set up in a feedback loop with the flow meter. Primary data taken in testing is location of stream breakup and water droplet size. This data is obtained using orthogonal video cameras and grids. The apparatus will utilize a wire grid, to allow water to flow down and back into the piston during the 2-g portion of the flight. Flow data is also taken using a flowmeter.

Sponsors

Water bridge

Break up point

Droplets

Ground Testing

C-9 during flight

References[1] S. P. Lin. Breakup of Liquid Sheets and Jets. Cambridge University Press. 2003.

Diagram of C-9 flight Path

Dimensional Analysis

d = diameter of stream [l]σ = surface tension [mt-2]g = gravity [lt-2]v = freestream velocity [lt-1]ρ = density [ml-3]μ = viscosity [ml-1t -1]Lbu = breakup distance [l]

We = Weber Number = ρv2d / σFr = Froude Number = v / √(Lg)Re = Reynold’s Number = ρvd / μ

In this problem the length where the column of fluid breaks up is a key research point and depends on many factors [1]:

Lbu = f( d, σ, g, v, ρ, μ )

This can be reduced to one dimensionless number which depends on three:

Lbu/d = f( We, Fr, Re )

Lbu

d

v

Modeled Urethra(surgical tubing)

MethodFirst ground testing will be preformed to gather data on wide range of parameters (see Dimensional Analysis). Primary data taken will be position of freestream break up and average flow velocity. Temperature, droplet and water bridge size will also be recorded. Initial testing will give a wide range of points to sample data during flight. Two simplified urethras, modeling a male and female, and will be flown.

Water Stream Breakup at Different Flow Rates

3

4

5

6

7

8

9

0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8

Flow Rate (L/min)

Length of Stream before Breakup Lbu (in)

Female ID 0.125"

Female ID 0.156"

Female ID 0.17"

Female ID 0.1875"

Male ID 0.125"