Naval Surface Warfare Center

About: Naval Surface Warfare Center is a facility organization based out in Washington D.C., District of Columbia, United States. It is known for research contribution in the topics: Radar & Sonar. The organization has 2855 authors who have published 3697 publications receiving 83518 citations. The organization is also known as: NSWC.

Chemical Kinetics of the Thermal Decomposition of NTO

Abstract: The kinetics of thermal decomposition of 3-nitro-2,4-dihydro-3H-1,2,4-triazol-5-one (NTO) in the temperature interval from 200 °C to 260 °C was investigated using a glass Bourdon gauge. The overall decomposition reaction includes two distinct stages: the fast first-order decomposition and the subsequent autocatalytic reaction. The importance of the first stage increases with increasing decomposition temperature and decreasing loading density of the Bourdon gauge (m/V). A period of preliminary heating, at a lower temperature, strongly influences the autocatalytic stage when the decomposition is carried out at a higher temperature. In the temperature domain 200–220 °C, the Arrhenius constants of the decomposition reaction are found to be close to the values usually observed for nitrocompounds: E=173 kJ/mol and log10k≈12.5 (s−1). It is shown that a simple model of NTO decomposition based on an autocatalytic reaction of the m-th order can describe the course of the decomposition at high temperature but the m number appears to be excessively high, up to 4. A new model of the decomposition is developed, including an initial monomolecular reaction, decomposition of the crystalline substance, and an autocatalytic reaction of NTO dissolved in liquid decomposition products. This model gives the common order of autocatalysis, m=1.

Magnetomechanical properties of single crystal Tb/sub x/Dy/sub 1-x/ under compressive stress

Abstract: The magnetic and magnetostrictive properties of the Tb/sub x/Dy/sub 1-x/ highly magnetostrictive alloys were measured in the region of large magnetostriction to anisotropy ratios (x=0.5, 0.6, and 0.67). Magnetizations and magnetostrictions under compressive stresses up to 25 MPa and fields up to 2 kOe were compared to theoretical curves. Field dependences clearly display magnetization discontinuities and magnetic rotation regions. From these data and from corresponding elastic modulus measurements, permeabilities, piezomagnetic d-constants (d/sub 33/), and elastic compliances were calculated. For some values of stress and magnetic field, Delta E effects >10 and coupling factors (k/sub 33/) approach unity. >

Vacuum Electronics: Status and Trends

Abstract: The vast preponderance of U.S. radar transmitters today use vacuum electronic amplifiers, spanning the spectrum from UHF to EHF. Enhancements to performance, reliability, and cost of ownership are being applied continuously to these systems; routine in-service life extensions mandate continuing vacuum electronics research and development to support system needs for the foreseeable future. In addition, exciting advances in vacuum electronics will provide dramatic improvements in millimeter-wave radar resolution, broadband low-noise power at microwave frequencies, compact high power sources operating at lower voltages, and life-cycle cost improvement. Recent progress in key enabling technologies, e.g., advanced device modeling and micro-fabrication, is expected to continue. This paper reviews the status and trends of vacuum electronics, with selected applications emphasizing recent advances in device performance in the microwave regime: multiple-beam klystrons (MBKs), microwave power modules (MPMs), and gyro-amplifiers in the millimeter-wave regime.

Evaluation of Pressure Side Film Cooling With Flow and Thermal Field Measurements—Part I: Showerhead Effects

Abstract: The goal of this study was to determine how showerhead blowing on a turbine vane leading edge affects of the performance of film cooling jets farther downstream. An emphasis was placed on measurements above the surface, i.e. flow visualization, thermal field, and velocity field measurements. The film cooling performance on the pressure side of a simulated turbine vane, with and without showerhead blowing, was examined. Results presented in this paper are for low mainstream turbulence; high mainstream turbulence effects are presented in the companion paper. At the location of the pressure side row of holes, the showerhead coolant extended a distance of about 3d from the surface (d is the coolant hole diameter). The pressure side was found to be subjected to high turbulence levels caused by the showerhead injection. Results indicate a greater dispersion of the pressure side coolant jets with showerhead flow due to the elevated turbulence levels.Copyright © 2002 by ASME