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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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At least 19 records

Additively Manufactured Wind Tunnel Balances for Propulsive Force Measurement

Propulsive forces and moments during powered descent are not understood well enough to design an entry, decent, and landing vehicle with high confidence using solely computational fluid dynamics modelling (CFD). Therefore, wind tunnel testing is required to quantify uncertainties in computational modeling and simulation. Wind tunnel balances are structural, high-precision, multi-axis force transducers that provide direct measurement of these aerodynamic forces and moments, however their complex designs make them costly and time consuming to produce and approaches used to manufacture them have not changed significantly since the 1960s. This work demonstrates that additive manufacturing (AM) can be used to manufacture wind tunnel balances with significantly reduced fabrication time and expense. Moreover, the design flexibility afforded by the additive manufacturing process has the potential to enable new capabilities with respect to measuring propulsion forces during entry, decent, and landing testing. Here we present two novel balance designs enabled by AM. One will provide direct measurement of aerodynamic interference forces and moments on powered descent models (retropropulsion forces) to support CFD validation and further development of Mars human landing vehicle concepts. The second design will be used to characterize a reaction control system during entry descent and landing testing over a wide Mach number range.

Wind tunnel balance↗

Research of low cost wind generator rotors

A feasibility program determined that it would be possible to significantly reduce the cost of manufacturing wind generator rotors by making them of cast urethane. Several high modulus urethanes which were structurally tested were developed. A section of rotor was also cast and tested showing the excellent aerodynamic surface which results. A design analysis indicated that a cost reduction of almost ten to one can be achieved with a small weight increase to achieve the same structural integrity as expected of current rotor systems.

Fertis, D. G.↗

A common geometric data-base approach for computer-aided manufacturing of wind-tunnel models and theoretical aerodynamic analysis

A more automated process to produce wind tunnel models using existing facilities is discussed. A process was sought to more rapidly determine the aerodynamic characteristics of advanced aircraft configurations. Such aerodynamic characteristics are determined from theoretical analyses and wind tunnel tests of the configurations. Computers are used to perform the theoretical analyses, and a computer aided manufacturing system is used to fabricate the wind tunnel models. In the past a separate set of input data describing the aircraft geometry had to be generated for each process. This process establishes a common data base by enabling the computer aided manufacturing system to use, via a software interface, the geometric input data generated for the theoretical analysis. Thus, only one set of geometric data needs to be generated. Tests reveal that the process can reduce by several weeks the time needed to produce a wind tunnel model component. In addition, this process increases the similarity of the wind tunnel model to the mathematical model used by the theoretical aerodynamic analysis programs. Specifically, the wind tunnel model can be machined to within 0.008 in. of the original mathematical model. However, the software interface is highly complex and cumbersome to operate, making it unsuitable for routine use. The procurement of an independent computer aided design/computer aided manufacturing system with the capability to support both the theoretical analysis and the manufacturing tasks was recommended.

See, M. J.↗

Design and Analysis of a Tool for Automated Fiber Placement of Composite Wind Tunnel Blades

For decades, composite wind tunnel blades have been constructed using labor-intensive hand layup processes. Automated Fiber Placement (AFP) is a relatively new technology that has not seen widespread use in manufacturing composite wind tunnel blades. AFP offers the potential for reduced manufacturing time, reduced cost, and improved consistency compared to traditional hand layup procedures. These manufacturing qualities are becoming increasingly important as existing wind tunnel blades are replaced due to impact damage or wear and tear from decades of use. Researchers at the NASA Langley Research Center are currently using the Integrated Structural Assembly of Advanced Composites (ISAAC) facility to investigate the feasibility of AFP for manufacturing composite wind tunnel blades. ISAAC uses manufacturing tools as surfaces on which to place fiber tows. A manufacturing tool was developed for using AFP to build a wind tunnel blade shape. This paper presents the structural design and analysis of this tool, for use with AFP, constructed from high temperature thermoplastics. The tool fabricated by this design process was successfully used for AFP and oven cure of two representative airfoil shaped composite structures.

Brian Mason↗

The development and manufacture of wood composite wind turbine rotors

The physical properties, operational experience, and construction methods of the wood/epoxy composite MOD 0A wind turbine blades are considered. Blades of this type have accumulated over 10,000 hours of successful operation at the Kahuku, Hawaii and Block Island, Rhode Island test sites. That body of experience is summarized and related to the structural concepts and design drivers which motivated the original design and choice of interior layout. Actual manufacturing experience and associated low first unit costs for these blades, as well as projections for high production rates, are presented. Application of these construction techniques to a wide range of other blade sizes is also considered.

Zuteck, M. D.↗

Modified Adaptive Control for Region 3 Operation in the Presence of Wind Turbine Structural Modes

Many challenges exist for the operation of wind turbines in an efficient manner that is reliable and avoids component fatigue and failure. Turbines operate in highly turbulent environments resulting in aerodynamic loads that can easily excite turbine structural modes, possibly causing component fatigue and failure. Wind turbine manufacturers are highly motivated to reduce component fatigue and failure that can lead to loss of revenue due to turbine down time and maintenance costs. The trend in wind turbine design is toward larger, more flexible turbines that are ideally suited to adaptive control methods due to the complexity and expense required to create accurate models of their dynamic characteristics. In this paper, we design an adaptive collective pitch controller for a high-fidelity simulation of a utility-scale, variable-speed horizontal axis wind turbine operating in Region 3. The objective of the adaptive pitch controller is to regulate generator speed, accommodate wind gusts, and reduce the excitation of structural modes in the wind turbine. The control objective is accomplished by collectively pitching the turbine blades. The adaptive collective pitch controller for Region 3 was compared in simulations with a baseline classical Proportional Integrator (PI) collective pitch controller. The adaptive controller will demonstrate the ability to regulate generator speed in Region 3, while accommodating gusts, and reducing the excitation of certain structural modes in the wind turbine.

Frost, Susan Alane↗

Advanced Solar Power Systems

The Advanced Solar Power System (ASPS) concentrator uses a technically sophisticated design and extensive tooling to produce very efficient (80 to 90%) and versatile energy supply equipment which is inexpensive to manufacture and requires little maintenance. The advanced optical design has two 10th order, generalized aspheric surfaces in a Cassegrainian configuration which gives outstanding performance and is relatively insensitive to temperature changes and wind loading. Manufacturing tolerances also have been achieved. The key to the ASPS is the direct absorption of concentrated sunlight in the working fluid by radiative transfers in a black body cavity. The basic ASPS design concepts, efficiency, optical system, and tracking and focusing controls are described.

Atkinson, J. H.↗

Force Measurement for Wind Tunnel Facilities - Current Practices and Research Investments

This presentation will provide an introduction to strain gage balances (force transducers) used in NASA’s wind tunnel facilities. It will cover the breadth of wind tunnel applications using balances ranging from cryogenic facilities to facilities with aero heating affects. Specific areas of expertise including six-component balance design and calibration will also be discussed. Moreover, research areas including additive manufacturing of wind tunnel balances, the development of topology optimization tools to produce novel force transducer geometries, and dynamic force measurement will also be highlighted.

Wind tunnel balance↗

Proposed Wind Turbine Aeroelasticity Studies Using Helicopter Systems Analysis

Advanced systems for the analysis of rotary wing aeroelastic structures (helicopters) are being developed at NASA Ames by the Rotorcraft Aeromechanics Branch, ARA. The research has recently been extended to the study of wind turbines, used for electric power generation Wind turbines play an important role in Europe, Japan & many other countries because they are non polluting & use a renewable source of energy. European countries such as Holland, Norway & France have been the world leaders in the design & manufacture of wind turbines due to their historical experience of several centuries, in building complex wind mill structures, which were used in water pumping, grain grinding & for lumbering. Fossil fuel cost in Japan & in Europe is two to three times higher than in the USA due to very high import taxes. High fuel cost combined with substantial governmental subsidies, allow wind generated power to be competitive with the more traditional sources of power generation. In the USA, the use of wind energy has been limited mainly because power production from wind is twice as expensive as from other traditional sources. Studies conducted at the National Renewable Energy Laboratories (NREL) indicate that the main cost in the production of wind turbines is due to the materials & the labor intensive processes used in the construction of turbine structures. Thus, for the US to assume world leadership in wind power generation, new lightweight & consequently very flexible wind turbines, that could be economically mass produced, would have to be developed [4,5]. This effort, if successful, would result in great benefit to the US & the developing nations that suffer from overpopulation & a very high cost of energy.

Ladkany, Samaan G.↗

Surface roughness studies for wind tunnel models used in high Reynolds number testing

This paper focuses on stylus and optical techniques for the measurement of surface roughness in wind tunnel models. The stylus instruments provide detailed information, such as surface profiles and area maps, that may then be used either to calculate statistical properties (i.e., the rms surface roughness) or to study individual surface peaks or other features. By contrast, certain optical techniques yield area-averaged statistical properties of the surface roughness directly. Two instruments that use the technique of optical angular scattering are compared. One is a research instrument that has been developed to study the basic scattering phenomena by testing the optical theories and surface models used in inverse calculations of statistical roughness parameters. The second instrument is more compact and is under development as a hand held, on-line device to be used during manufacture of wind tunnel models for the National Transonic Facility at NASA Langley Research Center. The scattering geometries for the two instruments are compared and results from these instruments and the stylus technique are shown for roughness specimens that are typical of the surface finish of wind tunnel models.

Vorburger, T. V.↗

Automated Fiber Placement of Composite Wind Tunnel Blades: Process Planning and Manufacturing

The ability to accurately manufacture large complex shapes in a consistent and repeatable manner has led to Automated Fiber Placement (AFP) being the predominant mode of manufacturing for large composite aerospace structures today. Currently, AFP is being considered for medium- and small-scale parts. Composite wind tunnel blades have traditionally been fabricated by hand layup for pre-impregnated or dry fabrics with resin infusion. Though well proven, the traditional fabrication method is laborious and tedious, and hence expensive. The project described in this paper used the Integral Structural Assembly of Advanced Composites (ISAAC) facility at the NASA Langley Research Center to build a manufacturing demonstration unit (MDU) with a shape representative of a wind tunnel blade. This MDU is used to discuss tooling, process planning, and fabrication. Additionally, details of the generic manufacturing workflow are presented.

Harik, Ramy↗

International Symposium on Magnetic Suspension Technology, Part 1

The goal of the symposium was to examine the state of technology of all areas of magnetic suspension and to review related recent developments in sensors and controls approaches, superconducting magnet technology, and design/implementation practices. The symposium included 17 technical sessions in which 55 papers were presented. The technical session covered the areas of bearings, sensors and controls, microgravity and vibration isolation, superconductivity, manufacturing applications, wind tunnel magnetic suspension systems, magnetically levitated trains (MAGLEV), space applications, and large gap magnetic suspension systems.

Nelson J Groom↗

International Symposium on Magnetic Suspension Technology, Part 2

In order to examine the state of technology of all areas of magnetic suspension and to review related recent developments in sensors and controls approaches, superconducting magnet technology, and design/implementation practices, a symposium was held. The proceedings are presented. The sessions covered the areas of bearings, sensors and controls, microgravity and vibration isolation, superconductivity, manufacturing applications, wind tunnel magnetic suspension systems, magnetically levitated trains (MAGLEV), space applications, and large gap magnetic suspension systems.

Groom, Nelson J.↗

Airborne Wind Shear Detection and Warning Systems: Fourth Combined Manufacturers' and Technologists' Conference, part 1

The purpose of the meeting was to transfer significant ongoing results of the NASA/FAA joint Airborne Wind Shear Program to the technical industry and to pose problems of current concern to the combined group. It also provided a forum for manufacturers to review forward-look technology concepts and for technologists to gain an understanding of the problems encountered by the manufacturers during the development of airborne equipment and the FAA certification requirements. The present document was compiled to record the essence of the technology updates and discussions which follow each.

Vicroy, Dan D.↗

Airborne Wind Shear Detection and Warning Systems: First Combined Manufacturers' and Technologists' Conference

The purpose of the meeting was to transfer significant, ongoing results gained during the first year of the joint NASA/FAA Airborne Wind Shear Program to the technical industry and to pose problems of current concern to the combined group. It also provided a forum for manufacturers to review forward-looking technology concepts and for technologists to gain an understanding of FAA certification requirements and the problems encountered by the manufacturers during the development of airborne equipment.

Spady, Amos A., Jr.↗

Airborne Wind Shear Detection and Warning Systems: Third Combined Manufacturers' and Technologists' Conference, part 2

The Third Combined Manufacturers' and Technologists' Conference was held in Hampton, Va., on October 16-18, 1990. The purpose of the meeting was to transfer significant on-going results of the NASA/FAA joint Airborne Wind Shear Program to the technical industry and to pose problems of current concern to the combined group. It also provided a forum for manufacturers to review forward-look technology concepts and for technologists to gain an understanding of the problems encountered by the manufacturers during the development of airborne equipment and the FAA certification requirements.

Vicroy, Dan D.↗