Code UG Weekly Notes 7-11-02

Physical Sciences Division
Weekly Highlights for Week Ending 7/11/2002

*** Indicates item is appropriate for the HQ senior staff and may appear
on the OBPR Web site: http://spaceresearch.nasa.gov

GENERAL

RICE GROUP FEATURED IN NATURE NEWS ARTICLE: The work of the group of Randy Hulet at Rice University on ultra-cold fermion gases was featured in a recent article in Nature Magazine, including a photo of the team. In the June 27 issue, Mark Haw describes the efforts of Hulet’s team and other groups to obtain a phase transition into a new state of matter, the fermion condensate state. Numerous applications of these fermion condensates are predicted, such as models for neutron stars, and a system for testing quantum theories. The article states that obtaining this new state is imminent, so you should hold your breath for the coming announcement of the discovery.

ISS FLIGHT PROGRAM

LOW TEMPERATURE FACILITY TEAM BRIEFS ISS CONTROL BOARD ON FLIGHT RELEASABLE ATTACH MECHANISM (FRAM) NEEDS: The LTMPF payload office has briefed the ISS Multilateral Payload Control Board on the decision to use the modified FRAM in design by Boeing for transporting the LTMPF up to the ISS, instead of using a standard FRAM with a custom LTMPF Adapter Plate. This decision is applicable to all NASA or NASDA payloads that use the FRAM instead of NASDA’s Payload Attach Mechanism.

LTMPF TEAM SCAVENGES PARTS FROM THE PREVIOUS LOW TEMPERATURE FLIGHT FACILITY: The Charged Particle Monitors and the Baroswitch from the low temperature flight apparatus for the earlier shuttle flights have been removed and are now stored in the LTMPF lab for possible reverse engineering and reuse on the LTMPF mission 1. The manufacturer of the baroswitch, Leybold Corporation, has confirmed that the switch is still available and can be purchased set at the applicable opening pressure of 6 Torr that was used for the Shuttle flights.

MICROGRAVITY RESEARCH PROGRAM OFFICE (MRPO) PAYLOAD OPERATIONS STATUS ON THE INTERNATIONAL SPACE STATION (ISS) UF2 STAGE: We have successfully completed Week#3 of Increment 5 and have entered into Week#4. All of our payloads are performing nominally at this moment. The Microgravity Science Glovebox (MSG) and one of the MSG experiments have started their setup activities. The MSG checkout and commissioning activities will start on Week #5, and processing activities on two materials science investigations will follow. Also on board, and operating, are three biotechnology experiments that deal with crystal growth and cell culture, one plant growth experiment and a second set of zeolite crystal growth.

SCIENCE HIGHLIGHTS

COMBUSTION SCIENCE:

GRAVITATIONAL EFFECTS ON PARTIALLY-PREMIXED FLAMES: The objective of the research, led by Prof. I. Puri of University of Illinois at Chicago, is to investigate the effects of gravity on the structure and stability of hydrogen-, methane-, and propane-air flames under partially premixed conditions by employing both numerical and experimental techniques. Recent microgravity tests conducted at the NASA-Glenn 2.2-second Drop Tower showed the partially premixed flames to be of a more spherical nature than in normal gravity. Clear changes in both inner and outer flames were observed. Very interestingly, reaction zones, which are merged under normal gravity conditions, became separate and distinct in microgravity. This underscores the importance of the low gravity tests in resolving the topology of the partially premixed reaction region. A parallel numerical modeling study focuses on investigating the relative importance of advection and diffusion fluxes on partially premixed flames established under microgravity and normal gravity conditions. Some of the assumptions in the numerical modeling of the flames are currently being reassessed since it was previously thought that the primary influence of buoyancy would be on the outer flame; however, the microgravity test results are calling this into question. (Point of Contact: 6711/U. Hegde, 3-8744)

EFFECTS OF ELECTRIC FIELDS ON SOOT PROCESSES IN NON-BUOYANT HAYDROCARBON-FUELED FLAMES: The primary objective of this investigation, led by Dr. Zeng-guang Yuan from National Center of Microgravity Research for Fluids and Combustion, is to study the effects of electric field strength, polarity, and frequency (i.e. D.C. and A.C.) on soot inception threshold and soot volume fractions in both diffusion and premixed hydrocarbon flames. The understanding of the roles of ions and neutral radicals in soot nucleation and soot growth will improve our understanding of the governing mechanisms controlling soot. The experimental approach is to employ a pair of concentric spherical electrodes in which the inner electrode also serves as a nozzle for fuel or fuel/oxidizer mixtures. In microgravity, a spherically symmetric flame can be established between the two electrodes. The major advantage of this configuration is that the gas velocity, the electric field and the trajectories of various particles in the flame are all co-linear and vary only along the radial direction. A new outer electrode has recently been designed which ensures a spherical outer electrode such that the flame in the solid angle covered by that portion can be well considered as in a spherical shape. The electric field inside the flame reaction zone is quite complicated because of simultaneous occurrence of a number of coupled process including ion generation, ion recombination, electric currents of positive and negative charge carriers, and changes of the field strengths. A set of equations that give a close-form formulation of the electric field in the flame region in a spherically symmetric system is obtained and solved for numerically. Recent theoretical analyses identified that in a true one-dimensional configuration, "ionic wind" does not exist. Ionic wind can only occur in a two- or three-dimensional case. It is commonly believed that the dominant effect of electric field on flames is due to ionic wind. Thus, the experiments of this project provide the unique situation to study pure chemical effect on flame caused by electric field.

UPCOMING EVENTS

Additional meetings and symposia can be found at: http://microgravity.grc.nasa.gov/ugml/ugmltext.htm