Engineering topics

Stocker, Dennis

Publications and source records attributed to Stocker, Dennis.

5 records

NASA NTRS2012

FLEX: A Decisive Step Forward in NASA's Combustion Research Program

Stemming from the need to prevent, detect and suppress on-board spacecraft fires, the NASA microgravity combustion research program has grown to include fundamental research. From early experiment, we have known that flames behave differently in microgravity, and this environment would provide an ideal laboratory for refining many of the long held principals of combustion science. A microgravity environment can provide direct observation of phenomena that cannot be observed on Earth. Through the years, from precursor work performed in drop towers leading to experiments on the International Space Station (ISS), discoveries have been made about the nature of combustion in low gravity environments. These discoveries have uncovered new phenomena and shed a light on many of the fundamental phenomena that drive combustion processes. This paper discusses the NASA microgravity combustion research program taking place in the ISS Combustion Integrated Rack, its various current and planned experiments, and the early results from the Flame Extinguishment (FLEX) Experiment.

Hickman, John M.↗

NASA NTRS2003

High-school Student Teams in a National NASA Microgravity Science Competition

The Dropping In a Microgravity Environment or DIME competition for high-school-aged student teams has completed the first year for nationwide eligibility after two regional pilot years. With the expanded geographic participation and increased complexity of experiments, new lessons were learned by the DIME staff. A team participating in DIME will research the field of microgravity, develop a hypothesis, and prepare a proposal for an experiment to be conducted in a NASA microgravity drop tower. A team of NASA scientists and engineers will select the top proposals and then the selected teams will design and build their experiment apparatus. When completed, team representatives will visit NASA Glenn in Cleveland, Ohio to operate their experiment in the 2.2 Second Drop Tower and participate in workshops and center tours. NASA participates in a wide variety of educational activities including competitive events. There are competitive events sponsored by NASA (e.g. NASA Student Involvement Program) and student teams mentored by NASA centers (e.g. For Inspiration and Recognition of Science and Technology Robotics Competition). This participation by NASA in these public forums serves to bring the excitement of aerospace science to students and educators.Researchers from academic institutions, NASA, and industry utilize the 2.2 Second Drop Tower at NASA Glenn Research Center in Cleveland, Ohio for microgravity research. The researcher may be able to complete the suite of experiments in the drop tower but many experiments are precursor experiments for spaceflight experiments. The short turnaround time for an experiment's operations (45 minutes) and ready access to experiment carriers makes the facility amenable for use in a student program. The pilot year for DIME was conducted during the 2000-2001 school year with invitations sent out to Ohio- based schools and organizations. A second pilot year was conducted during the 2001-2002 school year for teams in the six-state region of Illinois, Indiana, Michigan, Minnesota, Ohio, and Wisconsin. The third year for DIME was conducted during the 2002-2003 school year for teams from the fifty United States, the District of Columbia, and Puerto Rico. An annual national DIME program is planned for the foreseeable future. Presented in this paper will be a description of DIME, an overview of the planning and execution of such a program, results from the first three years, and lessons learned from the first national competition.

DeLombard, Richard↗

NASA NTRS2002

NASA Microgravity Science Competition for High-school-aged Student Teams

NASA participates in a wide variety of educational activities including competitive events. There are competitive events sponsored by NASA and student teams which are mentored by NASA centers. This participation by NASA in public forums serves to bring the excitement of aerospace science to students and educators. A new competition for highschool-aged student teams involving projects in microgravity has completed two pilot years and will have national eligibility for teams during the 2002-2003 school year. A team participating in the Dropping In a Microgravity Environment will research the field of microgravity, develop a hypothesis, and prepare a proposal for an experiment to be conducted in a microgravity drop tower facility. A team of NASA scientists and engineers will select the top proposals and those teams will then design and build their experiment apparatus. When the experiment apparatus are completed, team representatives will visit NASA Glenn in Cleveland, Ohio for operation of their facility and participate in workshops and center tours. Presented in this paper will be a description of DIME, an overview of the planning and execution of such a program, results from the first two pilot years, and a status of the first national competition.

DeLombard, Richard↗

NASA NTRS1997

Characteristics of Non-Premixed Turbulent Flames in Microgravity

The overall objectives of this research are: (1) to obtain and analyze experimental data on flame images, and the spatial and temporal distributions of temperature, radiation, velocity and gas-phase species in microgravity turbulent gas-jet diffusion flames; and (2) to utilize these data to validate and refine the existing predictive capabilities. Work on this project commenced in June 1996. The first investigations on turbulent gas-jet diffusion flames in microgravity were initiated by Bahadori and co-workers in 1991. These studies have shown that significant differences exist in the transition processes in normal-gravity and microgravity flames, and that the turbulent flames in microgravity behave very differently as compared to their buoyancy-dominated normal-gravity counterparts. For example, in the transition regime while the visible flame height, for given fuel and nozzle size, in normal gravity decreases, the height of the microgravity flame increases. In the fully developed turbulent regime, the normal-gravity flame height is independent of injection velocity, whereas the microgravity flame height continues to increase, although at a lower rate than in the laminar and transitional regimes. Other differences between the normal-gravity and microgravity flames arise in the jet shear-layer instability characteristics, extent of the transitional regime and blow-off limit characteristics.

Hegde, Uday↗

NASA NTRS1996

Demonstrating Reduced Gravity

A miniature drop tower, Reduced-Gravity Demonstrator is developed to illustrate the effects of gravity on a variety of phenomena including the way fluids flow, flames burn, and mechanical systems (such as pendulum) behave. A schematic and description of the demonstrator and payloads are given, followed by suggestions for how one can build his (her) own.

Pearlman, Howard↗