Download or read book Rail Gun Heat Transfer Analysis written by Mehrzad Bahri and published by . This book was released on 1989 with total page 112 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Current Diffusion in Rail gun Conductors written by and published by . This book was released on 1982 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: A method has been developed to analyze one- and two-dimensional, nonlinear current diffusion in rail-gun conductors. A nonlinear current-diffusion equation that accounts for the temperature dependence of electrical conductivity has been developed from Maxwell's equations. A finite-difference heat-transfer computer program was adapted to solve the current-diffusion and thermal-diffusion problems for rail-gun conductors in one and two dimensions. The nonlinear current-diffusion equation was also extended to account for the magnetic-field dependence of the magnetic permeability, thus allowing ferromagnetic materials to be considered. A one-dimensional finite-difference technique was developed for ferromagnetic materials. Two one-dimensional test problems that compare results with other analyses are discussed. A series of calculations of current density and rail temperature was done for various size rectangular rails. One analysis of current diffusion in a ferromagnetic material was also performed.

Download or read book Railgun Conductor Heating from Multiple Current Pulses written by and published by . This book was released on 1986 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: A numerical technique for solving current- and thermal-diffusion problems in railgun conductors has been used to study joule heating in rails that are subject to multiple current pulses. Copper rails that are 25 mm high by the 12.5 mm wide with a 20-mm-square bore and a current pulse with 1-MA peak current and 1-ms pulse width at half maximum were assumed. This combination of parameters is sufficient to accelerate an 80-g projectile to 2-3 km/s with which current pulse. Three parameters were varied in the analysis: the repetition rate or current pulse frequency (3.3 to 100 Hz), the coolant heat-transfer coefficient (5 x 104 and 5 x 105 W/m2 .K), and the coolant channel distribution in the rail. Detailed results are used to illustrate the acceptability or unacceptability of particular combinations of these parameters for operation at steady state. An uncooled rail was not acceptable for steady-state operation. Repetition rates of about 30 Hz were acceptable with the higher coolant heat-transfer coefficient and the best coolant-channel distribution; this included cooling the rail exterior surface.

Download or read book Investigation of Elliptical Cooling Channels for a Naval Electromagnetic Railgun written by Elizabeth Rose Kealey and published by . This book was released on 2005 with total page 95 pages. Available in PDF, EPUB and Kindle. Book excerpt: The future Naval Electromagnetic Railgun will use a mega-ampere electrical current to generate an electromagnetic force which accelerates a projectile to hypersonic velocities. The applied current can raise the bulk temperature of the rails by over 100 degrees Celsius, necessitating an active cooling system for the rails to sustain high rates of fire without incurring permanent damage to the gun. The electromagnetic force on the projectile and the rails creates a complicated stress state that varies as the projectile passes along the rail, first uniaxial then biaxial compression acts on the rails. In this study, a system of cooling channels for fluid flow down the length of the rails was considered, and channels with elliptical cross sections were examined. Elliptical shapes were considered due to the high surface area available for convection, relatively low impact on the stress distribution, and low stress concentration effect. By treating an elliptical channel as a variable area fin and varying the size and aspect ratio of the ellipse and the distance between channels, the heat transfer capability of a channel array was maximized based on given flow conditions and applied heat flux. The optimal channel design was further constrained by the applied compressive stresses. It was found that ellipses of different aspect ratios are optimal for the uniaxial and biaxial stress states, and the optimal channel design was limited by the competing effects of these two structural constraints. In order to test the thermal aspect of the design, a representative set of channels were machined into one third scale copper rails using wire electrical discharge machining. Tests were performed using both a steady state heat flux to determine the overall heat transfer coefficient and transient conditions to determine the system thermal relaxation time. In order to verify the structural aspect of the design, a finite element analysis was done on the rail cross section to compare the computational stress concentration factors with the theoretical correlations used in the literature. The results of both the thermal experiments and finite element analysis were found to be in reasonable agreement with the predicted results.

Download or read book Multiphysics and Multiscale Modeling written by Young W. Kwon and published by CRC Press. This book was released on 2015-10-05 with total page 426 pages. Available in PDF, EPUB and Kindle. Book excerpt: Written to appeal to a wide field of engineers and scientists who work on multiscale and multiphysics analysis, Multiphysics and Multiscale Modeling: Techniques and Applications is dedicated to the many computational techniques and methods used to develop man-made systems as well as understand living systems that exist in nature. Presenting a body

Download or read book Experimental Analysis and Predictive Modeling of Thermal Loading in a Railgun written by Joshua Monroe Keena and published by . This book was released on 2008 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book A Thermal Hydraulic Model of Melt Lubrication in Railgun Armatures written by and published by . This book was released on 2003 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: This paper describes the first step toward a model of the liquid film at the rail/armature interface in solid armature railguns. It considers high-speed Couette flow with purely viscous heating and does not include MHD body forces or Joule heating. The focus is on coupled fluid dynamics and multi-phase heat transfer. The formulation is similar to the analysis of melt lubrication in rotating projectile bands, but our first principles model allows the possibility of solidification while the armature is passing, a feature that has been missing from previous analyses. The model is moderately successful at reproducing results of experiments which measured high-speed mechanical wear of 7075 aluminum sliding against ETP copper for face pressures ranging from 6 to 22 ksi. Discrepancies between calculated and experimental results are attributed to uncertainties in modeling the complex phase change behavior of aluminum alloy 7075 and uncertain conditions at the rail interface.

Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1994 with total page 1028 pages. Available in PDF, EPUB and Kindle. Book excerpt: Lists citations with abstracts for aerospace related reports obtained from world wide sources and announces documents that have recently been entered into the NASA Scientific and Technical Information Database.

Download or read book The proceedings of the 16th Annual Conference of China Electrotechnical Society written by Xidong Liang and published by Springer Nature. This book was released on 2022-04-22 with total page 1396 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book gathers outstanding papers presented at the 16th Annual Conference of China Electrotechnical Society, organized by China Electrotechnical Society (CES), held in Beijing, China, from September 24 to 26, 2021. It covers topics such as electrical technology, power systems, electromagnetic emission technology, and electrical equipment. It introduces the innovative solutions that combine ideas from multiple disciplines. The book is very much helpful and useful for the researchers, engineers, practitioners, research students, and interested readers.

Download or read book Heat Analysis and Thermodynamic Effects written by Amimul Ahsan and published by BoD – Books on Demand. This book was released on 2011-09-22 with total page 410 pages. Available in PDF, EPUB and Kindle. Book excerpt: The heat transfer and analysis on heat pipe and exchanger, and thermal stress are significant issues in a design of wide range of industrial processes and devices. This book includes 17 advanced and revised contributions, and it covers mainly (1) thermodynamic effects and thermal stress, (2) heat pipe and exchanger, (3) gas flow and oxidation, and (4) heat analysis. The first section introduces spontaneous heat flow, thermodynamic effect of groundwater, stress on vertical cylindrical vessel, transient temperature fields, principles of thermoelectric conversion, and transformer performances. The second section covers thermosyphon heat pipe, shell and tube heat exchangers, heat transfer in bundles of transversely-finned tubes, fired heaters for petroleum refineries, and heat exchangers of irreversible power cycles. The third section includes gas flow over a cylinder, gas-solid flow applications, oxidation exposure, effects of buoyancy, and application of energy and thermal performance index on energy efficiency. The forth section presents integral transform and green function methods, micro capillary pumped loop, influence of polyisobutylene additions, synthesis of novel materials, and materials for electromagnetic launchers. The advanced ideas and information described here will be fruitful for the readers to find a sustainable solution in an industrialized society.

Download or read book Unsteady Heat Transfer Analysis for Chosen Ammunition and Gun written by and published by . This book was released on 1972 with total page 61 pages. Available in PDF, EPUB and Kindle. Book excerpt: A study is being made by personnel of the Research Directorate, Weapons Laboratory, WECOM to establish a capability to perform overall heat transfer analysis for any given dimensions of a weapon and for any specified propellant characteristics. With respect to this goal, the propellant gas convective heat transfer problem was divided into five subproblems: generation of thermochemical properties for any given propellant; transient inviscid compressible flow through the gun barrel, core flow; transient viscous compressible flow on the bore surface, boundary layers; unsteady heat diffusion through the gun tube, and unsteady free convection and radiation outside the gun tube. An exact numerical solution for the unsteady, compressible, inviscid momentum and continuity equations by the method of characteristics was obtained.

Download or read book Proceedings of the ASME Heat Transfer Division written by and published by . This book was released on 2005 with total page 1074 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Unsteady Heat Transfer Analysis for Any Ammunition Gun and Firing Schedule written by and published by . This book was released on 1973 with total page 16 pages. Available in PDF, EPUB and Kindle. Book excerpt: The propellant gas convective heat transfer problem is divided into several subproblems: Generation of thermochemical properties for any chosen propellant; analysis of transient, inviscid, compressible flow through the gun barrel; analysis of unsteady, viscous, compressible flow with arbitrary pressure gradients on the bore surface; analysis of transient heat diffusion through single or multi-layer gun tubes; analysis of unsteady free convection and radiation around the gun tube; and control of a sequence of procedures due to the nature of unknown and transient boundary conditions and also due to coupling between the problems.

Download or read book Proceedings of the ASME Heat Transfer Division 2005 written by and published by . This book was released on 2005 with total page 1070 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Research in Progress written by and published by . This book was released on 1982 with total page 284 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Use of Services for Family Planning and Infertility United States 1982 written by Gerry E. Hendershot and published by . This book was released on 1988 with total page 982 pages. Available in PDF, EPUB and Kindle. Book excerpt: The 1982 statistics on the use of family planning and infertility services presented in this report are preliminary results from Cycle III of the National Survey of Family Growth (NSFG), conducted by the National Center for Health Statistics. Data were collected through personal interviews with a multistage area probability sample of 7969 women aged 15-44. A detailed series of questions was asked to obtain relatively complete estimates of the extent and type of family planning services received. Statistics on family planning services are limited to women who were able to conceive 3 years before the interview date. Overall, 79% of currently mrried nonsterile women reported using some type of family planning service during the previous 3 years. There were no statistically significant differences between white (79%), black (75%) or Hispanic (77%) wives, or between the 2 income groups. The 1982 survey questions were more comprehensive than those of earlier cycles of the survey. The annual rate of visits for family planning services in 1982 was 1077 visits /1000 women. Teenagers had the highest annual visit rate (1581/1000) of any age group for all sources of family planning services combined. Visit rates declined sharply with age from 1447 at ages 15-24 to 479 at ages 35-44. Similar declines with age also were found in the visit rates for white and black women separately. Nevertheless, the annual visit rate for black women (1334/1000) was significantly higher than that for white women (1033). The highest overall visit rate was for black women 15-19 years of age (1867/1000). Nearly 2/3 of all family planning visits were to private medical sources. Teenagers of all races had higher family planning service visit rates to clinics than to private medical sources, as did black women age 15-24. White women age 20 and older had higher visit rates to private medical services than to clinics. Never married women had higher visit rates to clinics than currently or formerly married women. Data were also collected in 1982 on use of medical services for infertility by women who had difficulty in conceiving or carrying a pregnancy to term. About 1 million ever married women had 1 or more infertility visits in the 12 months before the interview. During the 3 years before interview, about 1.9 million women had infertility visits. For all ever married women, as well as for white and black women separately, infertility services were more likely to be secured from private medical sources than from clinics. The survey design, reliability of the estimates and the terms used are explained in the technical notes.

Download or read book A Heat Transfer Study in Folded Ammunition Gun Tube Chambers written by P. L. Versteegen and published by . This book was released on 1977 with total page 48 pages. Available in PDF, EPUB and Kindle. Book excerpt: Time dependent heat transfer analyses have been performed for folded gun tube chambers in that part of the gun tube that is sandwiched between the folded part of the shell casing and the projectile. The asymmetric configuration was believed to introduce 3-dimensional effects so that peak temperatures could not be determined adequately by 2-dimensional analyses. Calculations performed, however, showed that for the single round firing of a projectile a 1-dimensional representation could adequately estimate the peak temperature except for the interior corner region of the propellant capsule which required a 2-dimensional model. A representative set of time- and space-dependent gas temperatures and heat transfer coefficients for conventional unfolded ammunition was supplied by BRL. Maximum surface temperatures were found to occur at a region (named Location 13) near the origin of rifling. Data from this location was used for a 1-dimensional analysis of a non-corner region and a 2-dimensional analysis of a corner region. The calculated temperature rise for an SAE 4340 steel non-corner surface was 1003 deg C (1836 deg F). When a brass layer was used to simulate the cartridge case, the temperature rise was only 660 deg C (1220 deg F) for a non-corner region. However, for a corner region, the brass-coated surface temperature reached a maximum of 1099 deg C (2010 deg F). The results for the interior corner are only tentative because significant approximations were required to model the geometry and to specify the boundary conditions.