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Berge, L. H.

Publications and source records attributed to Berge, L. H..

7 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1982

Containerless melting and solidification of materials with an aerodynamic levitation system

A simple aerodynamic system which can heat, melt, cool, and solidify (in a containerless fashion) small, roughly spherical (diameter 1.5-4 mm) samples of materials is described. The principal components of the system are an aerodynamic levitation tube and an elliptical radiant heater. The materials processed, i.e., melted and resolidified, in the system include lead and an alkali borosilicate glass. The processing of a glass bead is described. In addition, the physical phenomena which may generate the levitation force in the tube are briefly discussed.

Oran, W. A.↗
NASA NTRS1981

Gas levitator having fixed levitation node for containerless processing

A method and apparatus is disclosed for levitating a specimen of material in a containerless environment at a stable nodal position independent of gravity. An elongated levitation tube has a contoured interior in the form of convergent section, constriction, and a divergent section in which the levitation node is created. A gas flow control means prevents separation of flow from the interior walls in the region of a specimen. The apparatus provides for levitating and heating the specimen simultaneously by combustion of a suitable gas mixture combined with an inert gas.

Berge, L. H.↗
NASA NTRS1980

Improved acoustic levitation apparatus

Concave driver and reflector enhance and shape levitation forces in acoustic resonance system. Single-mode standing-wave pattern is focused by ring element situated between driver and reflector. Concave surfaces increase levitating forces up to factor of 6 as opposed to conventional flat surfaces, making it possible to suspend heavier objects.

Berge, L. H.↗
NASA NTRS1980

Parametric study of an acoustic levitation system

The performance of an acoustic levitation system designed for the containerless processing of materials and consisting of a St. Clair generator and a reflector arranged in a six-axis configuration, is examined in order to define critical parameters of high-temperature systems and limitations of earth-based devices. The fields and forces along the axis of the system are measured and the forces are plotted versus body volume. It is found that for a range of shapes and sizes the levitation force is roughly proportional to body volume until the characteristic 'diameter' reaches a value of about lambda/2. A significant (i.e., factor of four) enhancement in the levitation force is obtained by curving the faces of the driver and reflector. In addition, the behavior of liquid materials in the acoustic fields is studied, and the radius at which the deformation of a levitated drop occurs is calculated.

Oran, W. A.↗
NASA NTRS1979

Preliminary characterization of a one-axis acoustic system

The acoustic fields and levitation forces produced along the axis of a single-axis resonance system were measured. The system consisted of a St. Clair generator and a planar reflector. The levitation force was measured for bodies of various sizes and geometries (i.e., spheres, cylinders, and discs). The force was found to be roughly proportional to the volume of the body until the characteristic body radius reaches approximately 2/k (k = wave number). The acoustic pressures along the axis were modeled using Huygens principle and a method of imaging to approximate multiple reflections. The modeled pressures were found to be in reasonable agreement with those measured with a calibrated microphone.

Oran, W. A.↗