Search

Manufacturing has evolved to become a critical element of the competitive skill set of defense aerospace firms. Given the changes in the acquisition environment and culture; traditional "thrown over the wall" means of developing and manufacturing products are insufficient. Instead, the development and manufacture of air and spacecraft require much more interaction between the various functions. Also, manufacturing systems are complex systems that need to be carefully designed in a holistic manner and there are shortcomings with available tools and methods to assist in the design of these systems. This thesis proposes and validates a framework to guide the manufacturing system design process. The exploration and validation activities used 14 case studies from major aerostructures, electronics, launch vehicles and spacecraft. Actual manufacturing system design processes were observed real-time or captured retrospectively. An evaluation tool was used to compare the actual manufacturing system design processes with the process proposed by the framework. This degree of congruence with the framework was then compared to a metric of actual/planned performance of the manufacturing system. The results of the framework congruence versus the actual/planned performance metric showed that the case studies that were able to meet their planned performance also had manufacturing system design processes that resembled the process proposed in the framework. But the results also illustrated the different traits between the cases that were able to meet their planned performance and those that were not. Looking at the commonalities between the cases in the groups led to the discovery of the determinants of superior performance: breadth of functional interaction through the design process, use of a manufacturing strategy, the status of the manufacturing function, customer involvement, co-location and an enterprise perspective.

Very high stresses could occur in long gun barrel wall during firing. The stresses induced are due to the propagation of axisymmetric longitudinal waves along the barrel. To study this propagation, the tube was modelled using medium thickness shell elements. The equations of motion thus obtained were discretised using the centred finite difference method and resolved explicitly using a specifically designed computer programme. The latter outputs the displacements and stresses for all nodal points in the barrel, at any time during the firing cycle. Validation against experimental results gave very good agreement. A parametric study was then constructed to evaluate the influence of certain parameters. Finally, the limits of the model were studied. The study was completed by comparison with finite element modelling., This article is from ADA404787 10th U.S. Army Gun Dynamics Symposium Proceedings

Although the study of wall pressure fluctuations (WPFs)has a long and venerable history, relatively little is known about the nature of the source terms responsible for the wall pressure. This study takes advantage of the three-dimensional velocity fields available from turbulence simulations to try to answer some long-standing questions about the nature of WPFs. Which parts of the boundary layer generate the various wave number regions of the wall pressure? What are the dominant source terms? What are the relative magnitudes of the mean-shear (MS) and turbulence-turbulence (TT)wall pressures? What physical processes in the boundary layer generate the wall pressure?, The original document contains color images.

A new lock is to be constructed at the McAlpine Locks on the Ohio River at Louisville, KY. The new lock chamber will be defined by rock-founded, gravity, earth-retaining monoliths. One of the alternatives is to construct the walls using roller compacted concrete (RCC) with a concrete facing, with the culverts located in the floor of the lock chamber. The principal objective of this study is to assess the soil-to-structure-to-foundation interactions of a typical RCC lock wall two-dimensional section. Due to the nature of the problem, the conventional analysis techniques, which are based upon the equations of equilibrium and assumed stress distributions made along imaginary sections, did not provide sufficient information to satisfactorily evaluate the performance of this structure with regard to its interaction with the rock foundation and soil backfill. The general-purpose, nonlinear, incremental construction, finite element computer program, SOILSTRUCT-ALPHA is used to analyze the complex interactions among the lock, the backfill, and the foundation rock strata. The analysis is accomplished in three phases. The first phase of the analysis introduces the self-weight of the existing locks and existing backfill to the shale and limestone foundation.

We have studied thin films composed of thin and thick wall template synthesized polypyrrole microtubules. We observe a crossover from three to one dimensional variable range hopping in our samples at low temperatutes. Our results clearly indicate that the geometry of the microtubules has an influence on the conductivity. The transition temperature from 3 to 1 dimensional variable range hopping shifts to lower temperatures when high pressure is applied. The results are discussed on the basis of the geometry of the microtubules.

During firing, the gun barrel centerline profile and muzzle pointing angle change due to thermal distortion. There are several causes of thermal distortion; we will discuss two: uneven cooling, and non-uniform wall thickness. We will briefly explain the mechanisms by which these two effects produce gun barrel bending and describe how these effects are modeled. We will demonstrate our model by predicting the muzzle pointing angle change for a particular gun tube firing five rounds, one every two minutes. The predictions are compared with experimental results; some agreement is noted., This article is from 'Proceedings of the U.S. Army Symposium on Gun Dynamics (7th) Held in Newport, Rhode Island on 11-13 May 1993', AD-A278 075, p272-281.

One of the major tasks for the development of novel airbreathing space transportation systems, operating from usual airports by horizontal take off and landing, is the integration of an advanced propulsion system in the cell of that spacecraft. The air intake and in particular the free expansion nozzle affect not only the efficiency of the engine but also severely the forces and moments, and with that the control, of the complete spacecraft. Therefore, of course, it is necessary to know in detail the flow fields through such nozzles and its interaction with the external airflow. Another project deals with conventional rocket motor nozzles where by injection of turbine exhaust gases in the expansion part of the nozzle the wall of the nozzle is cooled (film-cooling concept) and the thrust is slightly increased., This article is from 'CFD Techniques for Propulsion Applications Panel Symposium (77th) Held in San Antonio, Texas on 27-31 May 1991 (Les Techniques de l'Aerodynamique Numerique pour les Applications aux Propulseurs)', AD-253 647, p32-1 thru p32-11.

The mechanism of film cooling and heat transfer on gas turbine blades and endwalls is theoretically investigated by simultaniously solving the 3D Navier-Stokes equations for the flow field and the 3D heat conduction equation for the cooled blade. The coupling of flow calculation and heat conduction calculation in the turbine blades supplies the wall temperatures and heat fluxes at the blade surfaces. These have to be taken from measurements if a traditional boundary layer approach is used for calculating the corresponding heat transfer coefficients. Heat transfer coefficients and film cooling efficiencies resulting from the 3D solution are presented. Additionally a comparison between measured and calculated data is shown., This article is from 'CFD Techniques for Propulsion Applications Panel Symposium (77th) Held in San Antonio, Texas on 27-31 May 1991 (Les Techniques de l'A erodynamique Numerique pour les Applications aux Propulseurs)', AD-253 647, p7-1 thru p7-12.

At the request of the Department of Explosive Disposal of the Royal Netherlands Air Force (AEO-KLu) the possibilities of a modified punching charge has been investigated. The advantage of this concept is that it is flexible; and can be applied in several ways: linear, in a square shape and radial. Based on earlier experience one configuration was chosen: a rubber profile (to focus the shockwave) of 30 deg Shore hardness with a top film, a main charge of plastic explosive (no. 6) and sheet explosive based on RDX (DEMEX 200). With this configuration the minimum and maximum applicable amounts of explosive were determined on one bomb type. It can be concluded that the linear punching charge meets the expectations very well. Multiple linear charges can be successfully applied with a simple adjustment. The square shape is not applicable because of the narrow margins and the time consuming attaching. Radial punching charges can not (yet) be applied either. Used on a bomb with a wall thickness of 9 mm and a filling of cast TNT a minimum charge of 4.2 g/cm is necessary. The maximum charge is determined on 12 g/cm. The margin in between which the punching charge can be applied are to be determined for other types of bombs (different wall thickness and explosive filling).... Punching, Punding charges, Bombs, E.O.D. Tests, Text in Dutch, summary in Dutch and English.

This thesis examined and analyzed the Navy Military Housing acoustical design practices and procedures for military residential housing. The Uniform Building Code and Naval Facilities Engineering Command (NAVFACENGCOM) instruction 11101.85 were used as base line guidance for design and construction of Navy Family Housing Projects. NAVFACTENGCOM's design process was first examined to determine if more emphasis should be placed on noise suppression in Navy Family Housing. Based on the analysis, it was determined that the Navy Family Housing Program does address the design for noise suppression through the use of pre-established and factory tested Sound Transmission Class (STC) assemblies. However more emphasis should be placed on the acoustic evaluation process after a contractors' design is received for evaluation.

The goal of our research was to bridge the gap between modern ideas from dynamical systems and chaos and more traditional approaches to turbulence. In order to reach this objective we conducted theoretical and computational work on two systems: (1) a perturbed-Kelvin cat eyes flow, and (2) prototype solutions of the Navier-Stokes equations near solid walls. The main results obtained are two-fold: (a) we have been able to produce flows capable of producing complex distributions of vorticity, and (b) we have been able to construct flowfields, based on solutions of the Navier-Stokes equations, which are capable of displaying both Eulerian and Lagrangian turbulence. These results exemplify typical mechanisms of mixing enhancement in transitional flows. Fluid mechanics, Chaos, Mixing, Turbulence.

This appendix contains data from sampling and tests on the following: (1) Access shaft (Core) soil testing data; (2) Access shaft daily logs; (3) Bentonite slurry tests; (4) Hydrofraise productivity data; (5) Cutoff wall concrete aggregate gradations; (6) Cutoff wall concrete data; (7) Exploratory drilling logs and pressure tests; and (8) Dam (Raising) embankment materials data., Appendix to AD-A244 923.

Research and documented works on Viscous hypersonic flow theory are summarized and reported. Topic areas where the research has been focused are:(1) a fully viscous version of the shock layer (VSL) and its extension beyond the Navier-Stokes (NS) level based on Grad's thirteen moment equations (2) INVISCID-VISCOUS iteration in hypersonic flows. The development in area 1 has led to a principle which allows correlation of shock layer flow far from translational equilibrium with a corresponding flow based on the NS equations, as substantiated by extensive comparison of direct simulation Monte Carlo and NS-based calculations. The development in area 2 resulted in a triple-deck theory of hypersonic boundary layer under strong wall cooling which exhibits drastically different structure and properties of the triple-deck. (edc)

Wall pressure fluctuations within an equilibrium rectangular channel flow geometry were investigated. The overall objective of this investigation was to obtain experimentally for the first time, the statistical properties of the wall pressure fluctuations for a generic turbulent flow within a rectangular channel and to directly compare the results with those obtained from a full solution to the Navier-Stokes equations via Direct Numerical Simulation (DNS). For both the physical and computational experiments, serious limitations on the quality of the results were identified related to facility generated noise, transducer resolution, Reynolds number effects and constraints imposed by the computational technique. An extensive data base was obtained from the physical experiment. Profiles for the means and fluctuations components of the streamwise velocity were obtained at a number of spanwise locations and served to establish the existence of equilibrium flow conditions over a range of Reynolds numbers. An array of flush-mounted pressure transducers was utilized to measure the two point spectral characteristics in the stream-wise direction. A unique signal processing scheme was developed and used to cancel facility generated noise which resulted in new information being recorded at low frequencies for the Reynolds numbers investigated. Keywords: Noise cancellation; Wall pressure; Direct numerical simulation; Turbulent flow; Hydrodynamic flow noise. (JHD)

Sidewall and nozzle wall boundary layer profile parameters have been determined by a least-squares fit of a 'law of the wall' -- 'law of the wake' turbulent boundary layer equation to a number of experimental observations including some recent data from the BRL Supersonic Wind Tunnel No. 1. The parameters include: velocity scale, thickness, wake and wall region parameters. Quantitative comparisons have been made between boundary layer measurements in the BRL tunnel and other facilities. Variation of Mach number is found to effect the sidewall wake region considerably more than it effects the nozzle wall boundary layer and this is believed to be related to the differences in the upstream history of the two layers. (Author)

A major goal of the hydraulic ram survivability program for aircraft fuel tanks is the development of analytical-numerical tools for the accurate prediction of damage to the tank due to a ballistic projectile. This report presents a method for predicting the amount of cracking of a penetrated tank wall due to the penetrating projectile and the hydraulic ram loading. The method uses computer codes to predict the fluid pressure on the wall and the stresses in the wall. The stresses are compared with empirical data on the fracture of thin cracked plates to obtain a prediction of the final crack length. A comparison of predicted cracks with actual cracks that occurred in plates tested by Naval Weapons Center, China Lake, California is included. Good correlation is obtained when the magnitude of the predicted strains is adjusted to agree with the magnitude of the measured strains by a correction factor. (Author)

The analytical description of similarity-law velocity profiles for turbulent shear flow has been improved by a proposed polynomial which modifies the Coles law of the wake to satisfy the outer slope condition.