A solution for the space shuttle high temperature antenna problem
Design of high temperature antennas for space shuttles
Kuhlman, E. A.↗
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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.
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Development and integration of Spacelab payloads
Planning of payloads for future space missions requires that goals and objectives established by the scientific community be transformed into various instruments and equipment which can most effectively gather the scientific data necessary to realize these goals and objectives. The methodology for accomplishing this transformation is discussed, including the specific application of these methods to the development of Spacelab payloads. Several Spacelab payloads currently undergoing preliminary design are described together with their objectives, potential benefits, and the scientific requirements which 'drive' the payload concept and design. The concept for integrating the instruments and equipment into a Spacelab payload is discussed. This integration process is highlighted by describing two classes of Spacelab flights - one where the entire Spacelab is dedicated to a single scientific discipline and the other where the Spacelab is configured to accommodate payloads from several scientific disciplines. A brief description of the engineering approaches to the solution of some of the more interesting design problems is included.
Murphy, J. T.↗
The design and application of upwind schemes on unstructured meshes
Solution and mesh generation algorithms for solving the Euler equations on unstructured meshes consisting of triangle and quadrilateral control volumes are presented. Cell-centered and mesh-vertex upwind finite-volume schemes are developed which utilize multi-dimensional monotone linear reconstruction procedures. These algorithms differ from existing algorithms (even on structured meshes). Numerical results in two dimensions are presented.
Barth, Timothy J.↗
Space Discovery: Teaching with Space. Evaluation: Summer, Fall 1998 Programs
This is the final report of the 1998 NASA-sponsored evaluation of the effectiveness of the United States Space Foundation's five-day Space Discovery Standard Graduate Course (Living and Working in Space), the five-day Space Discovery Advanced Graduate Course (Advanced Technology and Biomedical Research), the five-day introductory course Aviation and Space Basics all conducted during the summer of 1998, and the Teaching with Space two-day Inservice program. The purpose of the program is to motivate and equip K- 12 teachers to use proven student-attracting space and technology concepts to support standard curriculum. These programs support the America 2000 National Educational Goals, encouraging more students to stay in school, increase in competence, and have a better opportunity to be attracted to math and science. The 1998 research program continues the comprehensive evaluation begun in 1992, this year studying five summer five-day sessions and five Inservice programs offered during the Fall of 1998 in California, Colorado, New York, and Virginia. A comprehensive research design by Dr. Robert Ewell of Creative Solutions and Dr. Darwyn Linder of Arizona State University evaluated the effectiveness of various areas of the program and its applicability on diverse groups. Preliminary research methodology was a set of survey instruments administered after the courses, and another to be sent in April-4-5 months following the last inservice involved in this study. This year, we have departed from this evaluation design in two ways. First, the five-day programs used NASA's new EDCATS on-line system and associated survey rather than the Linder/Ewell instruments. The Inservice programs were evaluated using the previously developed survey adapted for Inservice programs. Second, we did not do a follow-on survey of the teachers after they had been in the field as we have done in the past. Therefore, this evaluation captures only the reactions of the teachers to the programs immediately after the instruction. Although EDCATS is designed for teachers to enter their data logged onto the appropriate internet web site, most surveys were completed on a printed copy and entered into the EDCATS system by USSF personnel. The Aviation and Space Basics class were taken to a computer lab where they responded to the survey on-line. Data from the Inservice surveys were manually entered into a computer spreadsheet program by US Space Foundation personnel and processed using the statistical program SPSS for Windows. The raw data and copy of the EDCATS survey for the five-day programs are in Appendix 1. The raw data and copy of the Inservice survey are in Appendix 2. Comments from both programs are in Appendices 3 and 4, respectively.
Ewell, Bob↗
A method for obtaining reduced-order control laws for high-order systems using optimization techniques
A method of synthesizing reduced-order optimal feedback control laws for a high-order system is developed. A nonlinear programming algorithm is employed to search for the control law design variables that minimize a performance index defined by a weighted sum of mean-square steady-state responses and control inputs. An analogy with the linear quadractic Gaussian solution is utilized to select a set of design variables and their initial values. To improve the stability margins of the system, an input-noise adjustment procedure is used in the design algorithm. The method is applied to the synthesis of an active flutter-suppression control law for a wind tunnel model of an aeroelastic wing. The reduced-order controller is compared with the corresponding full-order controller and found to provide nearly optimal performance. The performance of the present method appeared to be superior to that of two other control law order-reduction methods. It is concluded that by using the present algorithm, nearly optimal low-order control laws with good stability margins can be synthesized.
Mukhopadhyay, V.↗
Iterative optimal subcritical aerodynamic design code including profile drag
A subcritical aerodynamic design computer code has been developed, which uses linearized aerodynamics along with sweep theory and airfoil data to obtain minimum total drag preliminary designs for multiple planform configurations. These optimum designs consist of incidence distributions yielding minimum total drag at design values of Mach number and lift and pitching moment coefficients. Linear lofting is used between airfoil stations. Solutions for isolated transport wings have shown that the solution is unique, and that including profile drag effects decreases tip loading and incidence relative to values obtained for minimum induced drag solutions. Further, including effects of variation of profile drag with Reynolds number can cause appreciable changes in the optimal design for tapered wings. Example solutions are also discussed for multiple planform configurations.
Kuhlman, J. M.↗
Materials processing in Space/Spacelab. FES/VCGS payload critical design review
A 25 mW He-Ne laser holographic recorder for recording the solution growth of triglycine sulfate crystals under low-zero gravity conditions is described. A systems engineering and design analysis, and mechanical and electrical design analyses of the equipmentation are presented. The equipment, fabricated for the Sl-3 flight on the space shuttle, was designed to take 300 holograms (two orthogonal views) on 50-235 film of each growth experiment. Specifications and capabilities for support module mechanical assemblies are lso presented.
Source record↗
A Modified Through-Flow Wave Rotor Cycle with Combustor Bypass Ducts
A wave rotor cycle is described which avoids the inherent problem of combustor exhaust gas recirculation (EGR) found in four-port, through-flow wave rotor cycles currently under consideration for topping gas turbine engines. The recirculated hot gas is eliminated by the judicious placement of a bypass duct which transfers gas from one end of the rotor to the other. The resulting cycle, when analyzed numerically, yields an absolute mean rotor temperature 18% below the already impressive value of the conventional four-port cycle (approximately the turbine inlet temperature). The absolute temperature of the gas leading to the combustor is also reduced from the conventional four-port design by 22%. The overall design point pressure ratio of this new bypass cycle is approximately the same as the conventional four-port cycle. This paper will describe the EGR problem and the bypass cycle solution including relevant wave diagrams. Performance estimates of design and off-design operation of a specific wave rotor will be presented. The results were obtained using a one-dimensional numerical simulation and design code.
Paxson Daniel E.↗
Architectural design and simulation of a virtual memory
Virtual memory is an imaginary main memory with a very large capacity which the programmer has at his disposal. It greatly contributes to the solution of the dynamic storage allocation problem. The architectural design of a virtual memory is presented which implements by hardware the idea of queuing and scheduling the page requests to a paging drum in such a way that the access of the paging drum is increased many times. With the design, an increase of up to 16 times in page transfer rate is achievable when the virtual memory is heavily loaded. This in turn makes feasible a great increase in the system throughput.
Kwok, G.↗
Numerical solution to the glancing sidewall oblique shock wave/turbulent boundary layer interaction in three-dimension
A supersonic three-dimensional viscous forward-marching computer design code called PEPSIS is used to obtain a numerical solution of the three-dimensional problem of the interaction of a glancing sidewall oblique shock wave and a turbulent boundary layer. Very good results are obtained for a test case that was run to investigate the use of the wall-function boundary-condition approximation for a highly complex three-dimensional shock-boundary layer interaction. Two additional test cases (coarse mesh and medium mesh) are run to examine the question of near-wall resolution when no-slip boundary conditions are applied. A comparison with experimental data shows that the PEPSIS code gives excellent results in general and is practical for three-dimensional supersonic inlet calculations.
Anderson, B. H.↗
Sensitivity Analysis and Optimization of Aerodynamic Configurations with Blend Surfaces
A novel (geometrical) parametrization procedure using solutions to a suitably chosen fourth order partial differential equation is used to define a class of airplane configurations. Inclusive in this definition are surface grids, volume grids, and grid sensitivity. The general airplane configuration has wing, fuselage, vertical tail and horizontal tail. The design variables are incorporated into the boundary conditions, and the solution is expressed as a Fourier series. The fuselage has circular cross section, and the radius is an algebraic function of four design parameters and an independent computational variable. Volume grids are obtained through an application of the Control Point Form method. A graphic interface software is developed which dynamically changes the surface of the airplane configuration with the change in input design variable. The software is made user friendly and is targeted towards the initial conceptual development of any aerodynamic configurations. Grid sensitivity with respect to surface design parameters and aerodynamic sensitivity coefficients based on potential flow is obtained using an Automatic Differentiation precompiler software tool ADIFOR. Aerodynamic shape optimization of the complete aircraft with twenty four design variables is performed. Unstructured and structured volume grids and Euler solutions are obtained with standard software to demonstrate the feasibility of the new surface definition.
Thomas, A. M.↗
Transient Response Dynamic Module Modifications to Include Static and Kinetic Friction Effects
A methodology that supports forced transient response dynamic solutions when both static and kinetic friction effects are included in a structural system model is described. Modifications that support this type of nonlinear transient response solution are summarized for the transient response dynamics (TRD) NASTRAN module. An overview of specific modifications for the NASTRAN processing subroutines, INITL, TRD1C, and TRD1D, are described with further details regarding inspection of nonlinear input definitions to define the type of nonlinear solution required, along with additional initialization requirements and specific calculation subroutines to successfully solve the transient response problem. The extension of the basic NASTRAN nonlinear methodology is presented through several stages of development to the point where constraint equations and residual flexibility effects are introduced into the finite difference Newmark-Beta recurrsion formulas. Particular emphasis is placed on cost effective solutions for large finite element models such as the Space Shuttle with friction degrees of freedom between the orbiter and payloads mounted in the cargo bay. An alteration to the dynamic finite difference equations of motion is discussed, which allows one to include friction effects at reasonable cost for large structural systems such as the Space Shuttle. Data are presented to indicate the possible impact of transient friction loads to the payload designer for the Space Shuttle. Transient response solution data are also included, which compare solutions without friction forces and those with friction forces for payloads mounted in the Space Shuttle cargo bay. These data indicate that payload components can be sensitive to friction induced loads.
Misel, J. E.↗
Design of two-dimensional channels with prescribed velocity distribution along the channel walls I : relaxation solutions
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Stanitz, John D↗
Hardware Design Improvements to the Major Constituent Analyzer
The Major Constituent Analyzer (MCA) onboard the International Space Station (ISS) is designed to monitor the major constituents of the ISS's internal atmosphere. This mass spectrometer based system is an integral part of the Environmental Control and Life Support System (ECLSS) and is a primary tool for the management of ISS atmosphere composition. As a part of NASA Change Request CR10773A, several alterations to the hardware have been made to accommodate improved MCA logistics. First, the ORU 08 verification gas assembly has been modified to allow the verification gas cylinder to be installed on orbit. The verification gas is an essential MCA consumable that requires periodic replenishment. Designing the cylinder for subassembly transport reduces the size and weight of the maintained item for launch. The redesign of the ORU 08 assembly includes a redesigned housing, cylinder mounting apparatus, and pneumatic connection. The second hardware change is a redesigned wiring harness for the ORU 02 analyzer. The ORU 02 electrical connector interface was damaged in a previous on-orbit installation, and this necessitated the development of a temporary fix while a more permanent solution was developed. The new wiring harness design includes flexible cable as well as indexing fasteners and guide-pins, and provides better accessibility during the on-orbit maintenance operation. This presentation will describe the hardware improvements being implemented for MCA as well as the expected improvement to logistics and maintenance.
Combs, Scott↗
Thermal analysis of HGFQ using FIDAP(trademark): Solidification front motion
The High Gradient Furnace with Quench (HGFQ) is being designed by NASA/MSFC for flight on the International Space Station. The furnace is being designed specifically for solidification experiments in metal and metallic alloy systems. The HGFQ Product development Team (PDT) has been active since January 1994 and their effort is now in early Phase B. Thermal models have been developed both by NASA and Sverdrup (support contractor) to assist in the HGFQ design effort. Both these models use SINDA as a solution engine, but the NASA model was developed using PATRAN and includes more detail than the Sverdrup model. These models have been used to guide design decisions and have been validated through experimentation on a prototypical 'Breadboard' furnace at MSFC. One facet of the furnace operation of interest to the designers is the sensitivity of the solidification interface location to changes in the furnace setpoint. Specifically of interest is the motion (position and velocity) of the solidification front due to a small perturbation in the furnace temperature. FIDAP(TM) is a commercially available finite element program for analysis of heat transfer and fluid flow processes. Its strength is in solution of the Navier-Stokes equations for incompressible flow, but among its capabilities is the analysis of transient processes involving radiation and solidification. The models presently available from NASA and Sverdrup are steady-state models and are incapable of computing the motion of the solidification front. The objective of this investigation is to use FIDAP(TM) to compute the motion of the solidification interface due to a perturbation in the furnace setpoint.
Woodbury, Keith A.↗
Multi-Objective Hybrid Optimal Control for Multiple-Flyby Interplanetary Mission Design using Chemical Propulsion
Preliminary design of high‐thrust interplanetary missions is a highly complex process. The mission designer must choose discrete parameters such as the number of flybys and the bodies at which those flybys are performed. For some missions, such as surveys of small bodies, the mission designer also contributes to target selection. In addition, real‐valued decision variables, such as launch epoch, flight times, maneuver and flyby epochs, and flyby altitudes must be chosen. There are often many thousands of possible trajectories to be evaluated. The customer who commissions a trajectory design is not usually interested in a point solution, but rather the exploration of the trade space of trajectories between several different objective functions. This can be a very expensive process in terms of the number of human analyst hours required. An automated approach is therefore very desirable. This work presents such an approach by posing the impulsive mission design problem as a multi‐objective hybrid optimal control problem. The method is demonstrated on several real‐world problems. Two assumptions are frequently made to simplify the modeling of an interplanetary high‐thrust trajectory during the preliminary design phase. The first assumption is that because the available thrust is high, any maneuvers performed by the spacecraft can be modeled as discrete changes in velocity. This assumption removes the need to integrate the equations of motion governing the motion of a spacecraft under thrust and allows the change in velocity to be modeled as an impulse and the expenditure of propellant to be modeled using the time‐independent solution to Tsiolkovsky's rocket equation [1]. The second assumption is that the spacecraft moves primarily under the influence of the central body, i.e. the sun, and all other perturbing forces may be neglected in preliminary design. The path of the spacecraft may then be modeled as a series of conic sections. When a spacecraft performs a close approach to a planet, the central body switches from the sun to that planet and the trajectory is modeled as a hyperbola with respect to the planet. This is known as the method of patched conics. The impulsive and patched‐conic assumptions significantly simplify the preliminary design problem.
Optimization↗
Growth of crystals from solutions in low gravity (A0139A)
The objective of the low gravity crystal growth experiments is to develop a novel solute diffusion method for growing single crystals. The experiments will utilize specially designed reactors with three or more compartments separated by valves to keep the reactant solutions and solvent separated until the apparatus reaches low gravity. There will be a mechanism for opening the valves automatically to initiate the diffusion and growth processes. The reactant reservoirs will be large enough to take advantage of the time provided by the Long Duration Exposure Facility (LDEF) flight. An array of several reactors will be mounted in a 12-in.-deep end center tray located on the Earth-facing end of the LDEF. Several reactors operating simultaneously will allow experimentation with more than one crystal growth system and/or variations of conditions for each. The reactors will be enclosed in a vacuum tight container and will be surrounded by thermal insulation. The temperature (approximately 35 deg C) will be regulated and any departures from the desired temperature will be recorded. Power requirements will be provided by LiSO2 batteries.
Lind, M. D.↗
Exploration Portable Life Support System Hatch Component Design
The design for the Exploration Extravehicular Mobility Unit (xEMU) is continuously being developed and many previous gaps in technologies have begun initial development. Various Exploration Portable Life Support System (xPLSS) Hatch components had been at a stall in technology development for many years including the Feedwater Supply Assembly, Trace Contaminant Control System, and the thermal loop filters. The challenging requirements and initial design of these components were previously discussed in “Exploration Portable Life Support System Hatch Component Design Challenges and Progress”. NASA has plans to go back to the Moon. The development of each of these components is relevant not only to the xEMU, but also to the International Space Station, Gateway, and commercial space businesses. As the xPLSS is being designed, built, integrated, and tested at the NASA Johnson Space Center, technology solutions will have a direct incorporation path as the xPLSS is matured to meet design and performance goals. This is a follow on paper to discuss the initial implementation of the hatch component designs, changes due to existing challenges, and performance results of these components as the xEMU project completes the first phase of towards flight, known as Design Verification Test (DVT).
Kristina Todd↗