Engineering topics

Pline, Alexander D.

Publications and source records attributed to Pline, Alexander D..

13 records

NASA NTRS1998

Oscillatory Thermocapillary Flow Experiment-2 (OTFE-2)

Oscillatory thermocapillary flow experiments were performed in the Glovebox aboard the USML-2 Spacelab which was launched on October 20, 1995. Open cylindrical containers of 1.2 and 2.0 cm in diameter were used. The ratio of container depth to radius (aspect ratio) was set at 0.5 and 2. Silicone oil of 2 centistokes kinematic viscosity was the test fluid. The fluid was heated by a cylindrical heater placed along the center axis of the container. The fluid motion was studied by flow visualization. The effect of aspect ratio on the onset of oscillations and on the oscillatory flow was investigated. It was found that the onset of oscillations was delayed when the container was made more shallow.

Kamotani, Yasuhiro↗

NASA NTRS1998

Experiment 6: Surface Tension Driven Convection Experiment-2 (STDCE-2)

Results are reported from the Second Surface Tension Driven Convection Experiment (STDCE-2) performed aboard the Second United States Microgravity Laboratory (USML-2), which flew as Space Shuttle mission STS-73 and launched on October 20, 1995. Oscillatory thermocapillary flows were investigated in open cylindrical containers filled with 2 centistokes kinematic viscosity (Pr=27 at 25 C) silicone oil. Two different heating modes were investigated in detail. The main objectives of the experiments were to determine the onset of oscillatory thermocapillary flow under highly reduced buoyancy and gravity conditions and to study the important features of the oscillatory flow. The onset conditions were determined in three different size containers (1.2-, 2-, and 3-cm diameter) and for various free surface shapes (flat and curved). Numerical and scaling analyses were also performed to understand the basic steady flows. The analysis shows that the main flow is viscous-dominated near the onset of oscillations. The onset conditions determined in the present experiments together with our earlier ground-based data show that one could not describe the oscillation phenomenon if the fluid free surface is assumed to be rigid. Therefore, a parameter representing free surface deformation was derived, and the data are shown to be correlated well by that parameter. The oscillation patterns and frequencies are also presented.

Ostrach, Simon↗

NASA NTRS1994

Particle-Displacement Tracking In Two Speed Ranges

Two NASA technical memorandums describe use of particle-displacement tracking (PDT) to generate maps of velocity vectors in flows in two different speed ranges. Second generation of particle-tracking technique previously discussed in "Processing Laser-Velocimetric Data by Vector Scanning" (LEW-14925).

Wernet, Mark P.↗

NASA NTRS1993

Development Of Infrared Imager For Spacelab

Terrestrial instrument modified for use in outer space. Report discusses progress in development of infrared-imaging instrument for use in microgravity scientific experiments in manned module in payload bay of Space Shuttle. Imager intended primarily for characterization of surface temperatures in microgravity fluid-physics experiment. Design versatile so instrument serves as "off-the-shelf" unit for other experiments, eliminating need to duplicate development and qualifications for spacecraft for future experiments.

Pline, Alexander D.↗

NASA NTRS1991

Particle image velocimetry for the surface tension driven convection experiment using a particle displacement tracking technique

The Surface Tension Driven Convection Experiment (STDCE) is a Space Transportation System flight experiment to study both transient and steady thermocapillary fluid flows aboard the USML-1 Spacelab mission planned for 1992. One of the components of data collected during the experiment is a video record of the flow field. This qualitative data is then quantified using an all electronic, two-dimensional particle image velocimetry technique called particle displacement tracking (PDT) which uses a simple space domain particle tracking algorithm. The PDT system is successful in producing velocity vector fields from the raw video data. Application of the PDT technique to a sample data set yielded 1606 vectors in 30 seconds of processing time. A bottom viewing optical arrangement is used to image the illuminated plane, which causes keystone distortion in the final recorded image. A coordinate transformation was incorporated into the system software to correct this viewing angle distortion. PDT processing produced 1.8 percent false identifications, due to random particle locations. A highly successful routine for removing the false identifications was also incorporated, reducing the number of false identifications to 0.2 percent.

Wernet, Mark P.↗

NASA NTRS1991

Ground-based PIV and numerical flow visualization results from the surface tension driven convection experiment

The Surface Tension Driven Convection Experiment (STDCE) is a Space Transportation System flight experiment to study both transient and steady thermocapillary fluid flows aboard the United States Microgravity Laboratory-1 (USML-1) Spacelab mission planned for June, 1992. One of the components of data collected during the experiment is a video record of the flow field. This qualitative data is then quantified using an all electric, two dimensional Particle Image Velocimetry (PIV) technique called Particle Displacement Tracking (PDT), which uses a simple space domain particle tracking algorithm. Results using the ground based STDCE hardware, with a radiant flux heating mode, and the PDT system are compared to numerical solutions obtained by solving the axisymmetric Navier Stokes equations with a deformable free surface. The PDT technique is successful in producing a velocity vector field and corresponding stream function from the raw video data which satisfactorily represents the physical flow. A numerical program is used to compute the velocity field and corresponding stream function under identical conditions. Both the PDT system and numerical results were compared to a streak photograph, used as a benchmark, with good correlation.

Pline, Alexander D.↗

NASA NTRS1991

Particle image velocimetry for the Surface Tension Driven Convection Experiment using a particle displacement tracking technique

Wernet, Mark P.↗

NASA NTRS1991

Ground-based PIV and numerical flow visualization results from the Surface Tension Driven Convection Experiment

The Surface Tension Driven Convection Experiment (STDCE) is a Space Transportation System flight experiment to study both transient and steady thermocapillary fluid flows aboard the United States Microgravity Laboratory-1 (USML-1) Spacelab mission planned for June, 1992. One of the components of data collected during the experiment is a video record of the flow field. This qualitative data is then quantified using an all electric, two dimensional Particle Image Velocimetry (PIV) technique called Particle Displacement Tracking (PDT), which uses a simple space domain particle tracking algorithm. Results using the ground based STDCE hardware, with a radiant flux heating mode, and the PDT system are compared to numerical solutions obtained by solving the axisymmetric Navier Stokes equations with a deformable free surface. The PDT technique is successful in producing a velocity vector field and corresponding stream function from the raw video data which satisfactorily represents the physical flow. A numerical program is used to compute the velocity field and corresponding stream function under identical conditions. Both the PDT system and numerical results were compared to a streak photograph, used as a benchmark, with good correlation.

Pline, Alexander D.↗

NASA NTRS1990

Spacelab qualified infrared imager for microgravity science applications

The Lewis Research Center is developing, under contract, a Spacelab (manned module in the Space Shuttle payload bay) qualified infrared imager for noncontact surface temperature measurement in the Surface Tension Driven Convection Experiment, a microgravity fluid physics experiment. A versatile design philosophy was used in order to provide other experiments with essentially an off the shelf Shuttle qualified instrument, eliminating the duplication of the rigorous development and flight qualification processes. An Inframetrics Model 600 Scanning Infrared Radiometer is being modified to satisfy both experimental and flight requirements, while maintaining the basic performance parameters of the commercial instrument. The modifications include an efficient, low power closed cycle cryogenic cooler to cool the detector, a ruggedized scanner mechanism, 8 bit A/D conversion, Mil-STD components (where possible), size and weight optimization, and the addition of a microprocessor to perform automatic gain control. Features such as detector spectral response, the addition of spectral filters, and target temperature ranges could easily be changed to make this instrument useful as both a qualitative and quantitative diagnostic tool for Spacelab microgravity experiments, in combustion and fluid physics.

Pline, Alexander D.↗

NASA NTRS1989

Development of an infrared imaging system for the surface tension driven convection experiment

An infrared imaging system is used to quantify the imposed surface temperature distribution along a liquid/gas free surface in support of the Surface Tension Driven Convection Experiment, a planned Space Transportation System flight experiment. For ground-based work a commercially available instrument was used to determine the feasibility of using this type of imaging system for this experiment. The ground-based work was used as a baseline for compiling specifications for a flight qualified imager to be designed, fabricated, tested and qualified for flight. The requirements and the specifications for the flight model are given along with the reasons for departures from the ground-based equipment. The flight qualification requirements discussed are a representative sample of the necessary procedures which must be followed to flight qualify diagnostic equipment for use aboard the STS. The potential problems and concerns associated with operating an imaging system on orbit are also discussed.

Pline, Alexander D.↗

NASA NTRS1989

Infrared surface temperature measurements for the surface tension driven convection experiment

In support of the Surface Tension Driven Convection Experiment (STDCE), a planned space transportation system (STS) flight experiment, a commercially available infrared thermal imaging system is used to quantify the imposed thermal signature along the free surface. The system was tested and calibrated for the STDCE with ground-based equivalents of the STDCE hardware. Before using the system, consideration was given to the radiation characteristics of the target (silicone oil). Absorption coefficients were calculated to understand the surface depth as seen by the imager and the penetration depth of the surface heater (CO2 laser). The performance and operational specifications for the imager and image processing system are described in detail to provide an understanding of the equipment. Measurements made with the system were compared to thermocouple measurements and a calculated surface temperature distribution. This comparison showed that in certain regions the IR imager measurements were within 5 percent of the overall temperature difference across the free surface. In other regions the measurements were within + or - 10 percent of the overall temperature gradient across the free surface. The effective emissivity of silicone oil for these experimental conditions was also determined. Measurement errors and their possible solutions are discussed.

Pline, Alexander D.↗

NASA NTRS1989

Development of an infrared imaging system for the surface tension driven convection experiment

An infrared imaging system is used to quantify the imposed surface temperature distribution along a liquid/gas free surface in support of the Surface Tension Driven Convection Experiment, a planned Space Transportation System flight experiment. For ground-based work a commercially available instrument was used to determine the feasibility of using the type of imaging system for this experiment. The ground-based work was used as a baseline for compiling specifications for a flight qualified imager to be designed, fabricated, tested and qualified for flight. The requirements and specifications for the flight model are given along with the reasons for departures from the ground-based equipment. The flight qualification requirements discussed are a representative sample of the necessary procedures which must be followed to flight qualify diagnostic equipment for use aboard the STS. The potential problems and concerns associated with operating an imaging system in orbit are also discussed.

Pline, Alexander D.↗

NASA NTRS1988

Containment of a silicone fluid free surface in reduced gravity using barrier coatings

In support of the Surface Tension Driven Convection Experiment planned for flight aboard the Space Shuttle, tests were conducted under reduced gravity in the 2.2-sec Drop Tower and the 5.0-sec Zero-G facility at the NASA Lewis Research Center. The dynamics of controlling the test fluid, a 10-cSt viscosity silicone fluid in a low gravity environment were investigated using different container designs and barrier coatings. Three container edge designs were tested without a barrier coating; a square edge, a sharp edge with a 45-deg slope, and a sawtooth edge. All three edge designs were successful in containing the fluid below the edge. G-jitter experiments were made in scaled down containers subjected to horizontal accelerations. The data showed that a barrier coating is effective in containing silicone fluid under g-levels up to 10 sup -1 sub g sub 0. In addition, a second barrier coating was found which has similar anti-wetting characteristics and is also more durable.

Pline, Alexander D.↗