A general method for determining optimum thrust nozzle contours for gas-particle flows.
Optimization analysis for axisymmetric rocket motor nozzle design based on assumptions for gas particle flow
GAS FLOW↗
SEARCH · Engineering Papers
Results for “optimum design”
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.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
Design of supersonic combustors based on pressure-area fields.
Supersonic combustor length and contours for optimum performance determined from one- dimensional pressure-area analysis
COMBUSTION EFFICIENCY↗
Analytical correlation of centrifugal compressor design geometry for maximum efficiency with specific speed
Centrifugal compressor performance was examined analytically to determine optimum geometry for various applications as characterized by specific speed. Seven specific losses were calculated for various combinations of inlet tip-exit diameter ratio, inlet hub-tip diameter ratio, blade exit backsweep, and inlet-tip absolute tangential velocity for solid body prewhirl. The losses considered were inlet guide vane loss, blade loading loss, skin friction loss, recirculation loss, disk friction loss, vaneless diffuser loss, and vaned diffuser loss. Maximum total efficiencies ranged from 0.497 to 0.868 for a specific speed range of 0.257 to 1.346. Curves of rotor exit absolute flow angle, inlet tip-exit diameter ratio, inlet hub-tip diameter ratio, head coefficient and blade exit backsweep are presented over a range of specific speeds for various inducer tip speeds to permit rapid selection of optimum compressor size and shape for a variety of applications.
Galvas, M. R.↗
Analysis and design of optimized truncated scarfed nozzles subject to external flow effects
Rao's method for computing optimum thrust nozzles is modified to study the effects of external flow on the performance of a class of exhaust nozzles. Members of this class are termed scarfed nozzles. These are two-dimensional, nonsymmetric nozzles with a flat lower wall. The lower wall (the cowl) is truncated in order to save weight. Results from a parametric investigation are presented to show the effects of the external flowfield on performance.
Shyne, Rickey J.↗
Analysis and design of optimized truncated scarfed nozzles subject to external flow effects
Rao's method for computing optimum thrust nozzles is modified to study the effects of external flow on the performance of a class of exhaust nozzles. Members of this class are termed scarfed nozzles. These are two-dimensional, nonsymmetric nozzles with a flat lower wall. The lower wall (the cowl) is truncated in order to save weight. Results from a parametric investigation are presented to show the effects of the external flowfield on performance.
Shyne, Rickey J.↗
The Design of Jet Pumps
This report shows that by applying both energy and impulse theorems the optimum throat dimension of the mixing nozzle and the best shape of intake can be predicted approximately in a relatively simple manner. The necessary length of the mixing nozzle follows from Prandtl's turbulent mixing theory. The calculations are carried out for the mixing of similar and dissimilar fluids.
Flugel, Gustav↗
The design of fins for air-cooled cylinders
An analysis was made to determine the proportions of fins made of aluminum, copper, magnesium, and steel necessary to dissipate maximum quantities of heat for different fin widths, fin weights, and air-flow conditions. The analysis also concerns the determination of the optimum fin proportions when specified limits are placed on the fin dimensions. The calculation of the heat flow in the fins is based on experimentally verified, theoretical equations. The surface heat-transfer coefficients used with this equation were taken from previously reported experiments. In addition to the presentation of fin-design information, this investigation shows that optimum fin dimensions are inappreciably affected by the differences in air flow that are obtained with different air-flow arrangements or by small changes in the length of the air-flow path.
Biermann, Arnold E↗
Development of FIR arrays with integrating amplifiers
The development of optimized photoconductor arrays suitable for far infrared space astronomical applications are described. Although the primary impetus is the production of a 16 by 16 element Ge:Ga demonstration array for SIRTF, the extension of this technology to Large Deployable Reflector (LDR) is considered. The optimization of Ge:Ga and Ge:Be photoconductor materials is discussed. In collaboration with Lawrence Berkeley Laboratory, measurements of FIR photoconductors with quantum efficiencies greater than 20 percent at 100 micrometers, and dark currents below 300 electrons/s are presented. Integrating J-FET amplifier technology is discussed. The current generation of integrating amplifiers has a demonstrated read noise of less than 20 electrons for an integration time of 100 s. The design is shown for a stackable 16 x n Ge:Ga array that utilizes a 16-channel monolithic version of the J-FET integrator. A part of the design is the use of a thin, thermally insulating substrate that allows the electronics to operate at the optimum temperature of 50 K while maintaining thermal and optical isolation from the detectors at 2 K. The power dissipation for the array is less than 16 mW. The array design may particularly be applicable to high resolution imaging spectrometers for LDR.
Young, Erick T.↗
TIES for Dummies 3rd Edition (Technology Identification, Evaluation, and Selection) Basic how to's to implement the TIES method
The TIES method is a forecasting environment whereby the decision-maker has the ability to easily assess and trade-off the impact of various technologies without sophisticated and time-consuming mathematical formulations. TIES provides a methodical approach where technically feasible alternatives can be identified with accuracy and speed to reduce design cycle time, and subsequently, life cycle costs, and was achieved through the use of various probabilistic methods, such as Response Surface Methodology and Monte Carlo Simulations. Furthermore, structured and systematic techniques are utilized from other fields to identify possible concepts and evaluation criteria by which comparisons can be made. This objective is achieved by employing the use of Morphological Matrices and Multi-Attribute Decision Making techniques. Through the execution of each step, a family of design alternatives for a given set of customer requirements can be identified and assessed subjectively or objectively. This methodology allows for more information (knowledge) to be brought into the earlier phases of the design process and will have direct implications on the affordability of the system. The increased knowledge allows for optimum allocation of company resources and quantitative justification for program decisions. Finally, the TIES method provided novel results and quantitative justification to facilitate decision making in the early stages of design so as to produce affordable and quality products.
Kirby, Michelle R.↗
Hypersonic wing test structure design, analysis, and fabrication
An investigation to provide the analyses, data, and hardware required to experimentally validate the beaded panel concept and demonstrate its usefulness as a basis for design of a Hypersonic Research Airplane (HRA) wing is reported. Combinations of the beaded panel structure, heat shields, channel caps and corrugated webs for ribs and spars were analyzed for the wing of a specified HRA to operate at Mach 8 with a lifespan of 150 flights. Detailed analyses were conducted in accordance with established design criteria and included aerodynamic heating and load predictions, transient structural thermal calculations, extensive NASTRAN computer modeling, and structural optimization. Optimum beaded panel tests at 922 K (1200 F) were performed to verify panel performance. Close agreement of predicted and actual critical loads permitted use of design procedures and equations for the beaded panel concept without modification.
Plank, P. P.↗
Modulur DIPS, 2.5-kWe modules for lunar/Mars surface applications, design point selection summary
The results are presented of a systematic series of studies leading to the selection and conceptual design development of a Dynamic Isotope Power System (DIPS) module for lunar and Martian surface applications. An optimum system configuration has been developed for the module that provides a system with a radiator area which is small and manageable without significantly impacting the system mass, efficiency, and technological risk. The maximum design temperature for the system has been determined.
Otting, William D.↗
HEART Aerothermodynamic Analysis
This paper presents an assessment of the aerothermodynamic environment around an 8.3 meter High Energy Atmospheric Reentry Test (HEART) vehicle. This study generated twelve nose shape configurations and compared their responses at the peak heating trajectory point against the baseline nose shape. The heat flux sensitivity to the angle of attack variations are also discussed. The possibility of a two-piece Thermal Protection System (TPS) design at the nose is also considered, as are the surface catalytic affects of the aeroheating environment of such configuration. Based on these analyses, an optimum nose shape is proposed to minimize the surface heating. A recommendation is also made for a two-piece TPS design, for which the surface catalytic uncertainty associated with the jump in heating at the nose-IAD juncture is reduced by a minimum of 93%. In this paper, the aeroshell is assumed to be rigid and the inflatable fluid interaction effect is left for future investigations.
Mazaheri, Alireza↗
High-Energy Atmospheric Reentry Test Aerothermodynamic Analysis
This paper presents an assessment of the aerothermodynamic environment around an 8.3 meter High Energy Atmospheric Reentry Test (HEART) vehicle. This study generated twelve nose shape configurations and compared their responses at the peak heating trajectory point against the baseline nose shape. The heat flux sensitivity to the angle of attack variations are also discussed. The possibility of a two-piece Thermal Protection System (TPS) design at the nose is also considered, as are the surface catalytic affects of the aeroheating environment of such configuration. Based on these analyses, an optimum nose shape is proposed to minimize the surface heating. A recommendation is also made for a two-piece TPS design, for which the surface catalytic uncertainty associated with the jump in heating at the nose-IAD juncture is reduced by a minimum of 93%. In this paper, the aeroshell is assumed to be rigid and the inflatable fluid interaction effect is left for future investigations
Mazaheri, Alireza↗
A PC program to optimize system configuration for desired reliability at minimum cost
High reliability is desired in all engineered systems. One way to improve system reliability is to use redundant components. When redundant components are used, the problem becomes one of allocating them to achieve the best reliability without exceeding other design constraints such as cost, weight, or volume. Systems with few components can be optimized by simply examining every possible combination but the number of combinations for most systems is prohibitive. A computerized iteration of the process is possible but anything short of a super computer requires too much time to be practical. Many researchers have derived mathematical formulations for calculating the optimum configuration directly. However, most of the derivations are based on continuous functions whereas the real system is composed of discrete entities. Therefore, these techniques are approximations of the true optimum solution. This paper describes a computer program that will determine the optimum configuration of a system of multiple redundancy of both standard and optional components. The algorithm is a pair-wise comparative progression technique which can derive the true optimum by calculating only a small fraction of the total number of combinations. A designer can quickly analyze a system with this program on a personal computer.
Hills, Steven W.↗
A quantitative method for photovoltaic encapsulation system optimization
It is pointed out that the design of encapsulation systems for flat plate photovoltaic modules requires the fulfillment of conflicting design requirements. An investigation was conducted with the objective to find an approach which will make it possible to determine a system with optimum characteristics. The results of the thermal, optical, structural, and electrical isolation analyses performed in the investigation indicate the major factors in the design of terrestrial photovoltaic modules. For defect-free materials, minimum encapsulation thicknesses are determined primarily by structural considerations. Cell temperature is not strongly affected by encapsulant thickness or thermal conductivity. The emissivity of module surfaces exerts a significant influence on cell temperature. Encapsulants should be elastomeric, and ribs are required on substrate modules. Aluminum is unsuitable as a substrate material. Antireflection coating is required on cell surfaces.
Garcia, A., III↗
MT's algorithm: A new algorithm to search for the optimum set of modulation indices for simultaneous range, command, and telemetry
MT's algorithm was developed as an aid in the design of space telecommunications systems when utilized with simultaneous range/command/telemetry operations. This algorithm provides selection of modulation indices for: (1) suppression of undesired signals to achieve desired link performance margins and/or to allow for a specified performance degradation in the data channel (command/telemetry) due to the presence of undesired signals (interferers); and (2) optimum power division between the carrier, the range, and the data channel. A software program using this algorithm was developed for use with MathCAD software. This software program, called the MT program, provides the computation of optimum modulation indices for all possible cases that are recommended by the Consultative Committee on Space Data System (CCSDS) (with emphasis on the squarewave, NASA/JPL ranging system).
Nguyen, Tien Manh↗
Evaluation of Novel Liner Concepts for Fan and Airframe Noise Reduction
This paper presents a review of four novel liner concepts: soft vanes, over-the-rotor liners, external liners, and flap side-edge liners. A number of similarities in the design and evaluation of these concepts emerged during these investigations. Since these were the first attempts to study these particular liner concepts, there was limited information to guide the design process. In all cases, the target frequencies (or frequency range) were known, but the optimum acoustic impedance and optimum liner placement were typically not known. For these cases, the maximum available surface was used and a c-impedance was targeted based on the assumption the sound field impinges on the surface at normal incidence. This choice proved fruitful for every application. An impedance prediction model was used to design variable-depth liner configurations, and a graphical design code (ILIAD) was developed to aid in this process. The ability to build increasingly complex liner configurations via additive manufacturing was key, such that multiple designs could quickly be tested in a normal incidence impedance tube. The Two-Thickness Method was used to evaluate available bulk materials, such that bulk liners could also be considered for each application. These novel liner concepts provide sufficient noise reduction to warrant further investigations.
Jones, M. G.↗
Accuracy Assessment of Response Surface Approximations for Supersonic Turbine Design
There is a growing trend to employ CFD tools to supply the necessary information for design optimization of fluid dynamics components/systems. Such results are prone to uncertainties due to reasons including discretization. errors, incomplete convergence of computational procedures, and errors associated with physical models such as turbulence closures. Based on this type of information, gradient-based optimization algorithms often suffer from the noisy calculations, which can seriously compromise the outcome. Similar problems arise from the experimental measurements. Global optimization techniques, such as those based on the response surface (RS) concept are becoming popular in part because they can overcome some of these barriers. However, there are also fundamental issues related to such global optimization technique such as RS. For example, in high dimensional design spaces, typically only a small number of function evaluations are available due to computational and experimental costs. On the other hand, complex features of the design variables do not allow one to model the global characteristics of the design space with simple quadratic polynomials. Consequently a main challenge is to reduce the size of the region where we fit the RS, or make it more accurate in the regions where the optimum is likely to reside. Response Surface techniques using either polynomials or and Neural Network (NN) methods offer designers alternatives to conduct design optimization. The RS technique employs statistical and numerical techniques to establish the relationship between design variables and objective/constraint functions, typically using polynomials. In this study, we aim at addressing issues related to the following questions: (1) How to identify outliers associated with a given RS representation and improve the RS model via appropriate treatments? (2) How to focus on selected design data so that RS can give better performance in regions critical to design optimization? (3) How to combine NN and polynomial techniques for improving the accuracy of the RS model?
Papila, Nilay↗