Engineering topics

Schonfeld, D.

Publications and source records attributed to Schonfeld, D..

7 records

NASA NTRS1984

NASTRAN Structural Model for the Large 64-meter Antenna Pedestal. Part 3: Applications to Hydrostatic Bearing Oil Film

Investigations are conducted on the 64-meter antenna hydrostatic bearing oil film thickness under a variety of loads and elastic moduli. These parametric studies use a NASTRAN pedestal structural model to determine the deflections under the hydrostatic bearing pad. The deflections form the input for a computer program to determine the hydrostatic bearing oil film thickness. For the future 64-meter to 70-meter antenna extension and for the 2.2-meter (86-in.) haunch concrete replacement cases, safe oil film thickness (greater than 0.13 mm (0.005 in.) at the corners of the pad) are predicted. The effects of varying moduli of elasticity for different sections of the pedestal and the film height under distressed runner conditions are also studied.

Chian, C. T.↗

NASA NTRS1983

Thermal Analysis of Antenna Structures. Part 2: Panel Temperature Distribution

This article is the second in a series that analyzes the temperature distribution in microwave antennas. An analytical solution in a series form is obtained for the temperature distribution in a flat plate analogous to an antenna surface panel under arbitrary temperature and boundary conditions. The solution includes the effects of radiation and air convection from the plate. Good agreement is obtained between the numerical and analytical solutions.

Schonfeld, D.↗

NASA NTRS1982

Thermal analysis of antenna backup structure. Part 1. Methodology development

An analytic method was devised to predict the temperature distribution in typical antenna structural back-up members. The results are in agreement with those obtained by a numerical shooting method. The analytic method shows potential in simplifying the thermal analysis process for complex back-up antenna structures.

Schonfeld, D.↗

NASA NTRS1982

Analysis of capacitive heat exchangers, part 2

The performance of a simple capacitive heat exchanger was analyzed. The shooting method for solving the governing equations is presented. Simplified linear and nonlinear models are analyzed using this method and it is shown that capacitive heat exchangers are more efficient than conventional ones.

Schonfeld, D.↗

NASA NTRS1981

Analysis of capacitive heat exchangers, part 1

Governing equations are developed for a simple capacitive heat exchanger. This type of heat exchanger consists of hot spherical particles falling through an ascending cold gas stream. The assumptions made in deriving the continuity, momentum and energy equations are clearly stated. The analysis yields a system of first order, ordinary, nonlinear equations which form a complex boundary value problem. The method of solution is presented together with a comparison between the performance of capacitive heat exchangers and conventional counter flow ones.

Schonfeld, D.↗

NASA NTRS1981

Fuel cells feasibility

The technical and economic status of fuel cells is assessed with emphasis on their potential benefits to the Deep Space Network. The fuel cell, what it is, how it operates, and what its outputs are, is reviewed. Major technical problems of the fuel cell and its components are highlighted. Due to these problems and economic considerations it is concluded that fuel cells will not become commercially viable until the early 1990s.

Schonfeld, D.↗

NASA NTRS1980

A survey of numerical models for wind prediction

A literature review is presented of the work done in the numerical modeling of wind flows. Pertinent computational techniques are described, as well as the necessary assumptions used to simplify the governing equations. A steady state model is outlined, based on the data obtained at the Deep Space Communications complex at Goldstone, California.

Schonfeld, D.↗