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Technical Paper

Ceramic Coating for Aluminum Engine and Components

1996-04-01
91A105
The trend toward lighter vehicles for improved performance has recently introduced the use of aluminum and plastic materials for vehicle bodies and drive trains. In particular, the aluminum alloy block foar engine application is certain to reappear. The soft aluminum cylinder liner will require additional treatment before acceptance. Three possible approaches appear to solve the aluminum cylinder liner dilemma. These approaches are: 1) use of high silicon aluminum such as the 390 aluminum; 2) insert or cast steel liners into the aluminum engine block; and 3) ceramic coat the low cost standard aluminum engine block. Each has known advantages and disadvantages. It is the purpose of this paper to present the merits of option 3, the ceramic coated aluminum cylinder bore, from the standpoint of low weight, cost, and tribological effectiveness. The advantages of approaches 1) and 2) are obvious. High temperature after treatment of the ceramic engine components is not required.
Technical Paper

Practical Applications of SEA CAE Analysis in Vehicle Sound Package Development

1999-05-17
1999-01-1702
Vehicle sound package serves two basic functions: general acoustic insulation and local problem treatment. The former is often done at the up-front phase of the vehicle development process, and the latter at the downstream phase when representative prototype hardware becomes available and specific noise problems are identified. This paper examines the goals and key tasks of practical SEA CAE applications in the two phases of the sound package development process. Topics on CAE model requirement, typical analysis applications, and ways to improve the effectiveness of SEA applications to compliment hardware testing are discussed.
Technical Paper

The Next Step in Acoustical Part Weight Reduction

1999-05-17
1999-01-1685
Weight reduction with maintained part performance is a continuing trend throughout the automotive industry. Acoustical insulation parts (carpet underlay and dash insulators) are no exception. Several years ago, ICI Polyurethanes led the industry in establishing a molded density standard of 48 kg/m3. Although this is the current production standard, the technology drive is toward even lower weights. Recent technological demonstrations show that molded densities of 35-38 kg/m3 are achievable. In addition to removing weight, acoustical performance can be maintained with no deficiencies in physical characteristics.
Technical Paper

A Dissipative Approach to Vehicle Sound Abatement

1999-05-17
1999-01-1668
This paper explores the performance of light weight attenuators, which take a dissipative approach to sound abatement in the motor vehicle. An analytical model is used to predict the sound transmission loss and random incidence sound absorption of attenuators, absorbers and sandwich insulation systems. Then, a mathematical expression is developed which combines the dissipative and sound transmission loss performance to determine the total noise reduction provided in the vehicle. Using this equation, the performance of multi-layered attenuators is shown to be comparable to, or better than that of sandwich insulators. Finally, test results from various studies in vehicles show that significant weight savings can be realized by using these multi-layered attenuators, which take a dissipative approach to vehicle sound insulation, rather than the traditional sandwich insulation system.
Technical Paper

Advanced Space Suit Insulation Feasibility Study

2000-07-10
2000-01-2479
For planetary applications, the space suit insulation has unique requirements because it must perform in a dynamic mode to protect humans in the harsh dust, pressure and temperature environments. Since the presence of a gaseous planetary atmosphere adds significant thermal conductance to the suit insulation, the current multi-layer flexible insulation designed for vacuum applications is not suitable in reduced pressure planetary environments such as that of Mars. Therefore a feasibility study has been conducted at NASA to identify the most promising insulation concepts that can be developed to provide an acceptable suit insulation. Insulation concepts surveyed include foams, microspheres, microfibers, and vacuum jackets. The feasibility study includes a literature survey of potential concepts, an evaluation of test results for initial insulation concepts, and a development philosophy to be pursued as a result of the initial testing and conceptual surveys.
Technical Paper

Operation of an Electronic Nose Aboard the Space Shuttle and Directions for Research for a Second Generation Device

2000-07-10
2000-01-2512
A flight experiment to test the operation of an Electronic Nose developed and built at JPL and Caltech was done aboard STS-95 in October-November, 1998. This ENose uses conductometric sensors made of insulating polymer-carbon composite films; it has a volume of 1.7 liters, weighs 1.4 kg including the operating computer and operates on 1.5 W average power. In the flight experiment, the ENose was operated continuously for 6 days and recorded the sensors' response to changes in air in the mid-deck of the orbiter. The ENose had been trained to identify and quantify ten common contaminants at the 24-hour Spacecraft Maximum Allowable Concentration (SMAC) level. Most SMACs are on the order of 10-100 ppm. The experiment was controlled by collecting air samples daily and analyzing them using standard analytical techniques after the flight. The device is microgravity insensitive.
Technical Paper

EO-1 Spacecraft Thermal Design and Analysis: Using the Thermal Synthesis System (TSS) and SINDA/FLUINT

2000-07-10
2000-01-2522
The thermal design and analysis of the Earth Observing-1 (EO-1) spacecraft, built by Swales Aerospace for NASA's Goddard Space Flight Center (GSFC), consisted of a Thermal Synthesis System1 (TSS) geometric math model (GMM) and a SINDA/FLUINT2 thermal math model (TMM). These models took advantage of the submodel capability of TSS and SINDA/FLUINT providing a simplified approach for merging spacecraft and instrument models. In addition to the spacecraft thermal model, there is the Advanced Land Imager (ALI) instrument model by MIT/LL, the Hyperion instrument by TRW, the Atmospheric Corrector (AC) instrument by GSFC, and the New Millenium Program (NMP) experiments. Separate thermal models were developed for each NMP experiment which included, the Pulse Plasma Thruster (PPT) by Primex, Lightweight Flexible Solar Array (LFSA) by Lockheed, X-Band Phased Array by Boeing and the Carbon-Carbon Radiator that was developed as a joint effort between NASA and industry.
Technical Paper

Aircraft Electrical System Safety Considerations: Arc Fault Circuit Interrupters

2000-04-11
2000-01-2121
The power distribution architecture in today’s aircraft typically use electromechanical circuit protection. These circuit breakers use a bimetal element to mimic the thermal impact on the wire and insulation caused by the carrying of current by the wire. Current running through the breaker heats the bimetal until it reaches its thermal set point and initiates a mechanical movement that opens the circuit breaker. As a safety and convenience feature, the breaker can be thought of as a re-settable fuse. Existing circuit breakers are quite effective in fulfilling their primary role of protecting wire and cable from damage due to current overloads. However, it has long been recognized that merely modeling the I2R heating has not totally eliminated wire insulation, cable, and load damage. Evidence of the problem can be gleaned from the continued progression of wire insulation systems and today’s concerns about an aging aircraft fleet.
Technical Paper

Characterization of an Integral Thermal Protection and Cryogenic Insulation Material for Advanced Space Transportation Vehicles

2000-07-10
2000-01-2236
NASA’s planned advanced space transportation vehicles will benefit from the use of integral/conformal cryogenic propellant tanks which will reduce the launch weight and lower the earth-to-orbit costs considerably. To implement the novel concept of integral/conformal tanks requires developing an equally novel concept in thermal protection materials. Providing insulation against reentry heating and preserving propellant mass can no longer be considered separate problems to be handled by separate materials. A new family of materials, Superthermal Insulation (STI), has been conceived and investigated by NASA’s Ames Research Center to simultaneously provide both thermal protection and cryogenic insulation in a single, integral material. The present paper presents the results of a series of proof-of-concept tests intended to characterize the thermal performance of STI over a range of operational conditions representative of those which will be encountered in use.
Technical Paper

Design Considerations and Thermal Analyses of the Space Telescope Imaging Spectrograph (STIS) Thermal Interface Kit (STIK)

2000-07-10
2000-01-2271
The Space Telescope Imaging Spectrograph (STIS) was installed on the Hubble Space Telescope (HST) during the HST's Second Servicing Mission (SM-2) in February 1997. Since the HST was deployed in April 1990, the effective thermal sinks seen by the spacecraft's science instruments have increased due to a degradation of the multilayer insulation (MLI) on the external surfaces of the HST and due to the increased power dissipated in the HST's aft shroud by the second and third generation science instruments. In order to maintain the instruments detectors at their required temperatures, the Aft Shroud Cooling System (ASCS) was designed and will be installed during the HST's Servicing Mission 3B (SM-3B) which is scheduled for July 2001.
Technical Paper

Low Temperature, Low Energy Carrier (LoTEC©) and Phase Change Materials (PCMs) for Biological Samples

2000-07-10
2000-01-2280
LoTEC© is a passive thermal carrier designed to maintain the temperature of biological samples for ten days or more for transport to and from the International Space Station (ISS) without the need of external power. LoTEC© relies on a combination of high thermal resistance insulation and high energy density storage phase change materials. The initial capability of LoTEC© encompasses several temperature ranges (e.g. 36 to 40C, 18 to 22C, 0 to 4C, and - 16 to -20C). LoTEC© fits into a standard mid-deck locker or an Express Rack locker; this facilitates easy transfer between the shuttle and the ISS. Thermal analysis modeling and laboratory test results are presented that characterize the performance of LoTEC© and the planned PCM materials.
Technical Paper

Thermal Conductivity of Lofty Nonwovens in Space and Planetary Vacuum Environment

2001-07-09
2001-01-2166
For planetary exploration, new thermal insulation materials are needed to deal with unique environmental conditions presented to extravehicular activity (EVA). The thermal insulation material and system used in the existing space suit were specifically designed for low orbit environment. They are not adequate for low vacuum condition commonly found in planetary environments with a gas atmosphere. This study attempts to identify the types of lofty nonwoven thermal insulation materials and the construction parameters that yield the best performance for such application. Lofty nonwovens with different construction parameters are evaluated for their thermal conductivity performance. Three different types of fiber material: solid round fiber, hollow fiber, and grooved fiber, with various denier, needling intensity, and web density were evaluated.
Technical Paper

Thermal Study of Laser Interferometer Space Antenna (Lisa)

2001-07-09
2001-01-2259
The objective of the Laser Interferometer Space Antenna (LISA) mission is the detection of low-frequency gravitational waves. The fluctuation of the distance of test masses inside 3 spacecraft’s which are located 5·106km apart is measured with an accuracy of 10−12m to achieve this. This requires very stringent temperature stability. Variations of solar constant, dissipation and the response to switching/mode changes cause temperature fluctuations that have to be suppressed. The spacecraft thermal design relies on a solar array as a sun shield with good thermal de-coupling between the solar cells and the structure and rejection of heat from the electronics directly to space. MLI is avoided because of its potentially unstable insulation properties. Transient analyses were performed with a temperature accuracy of 10−8 K. It was found that the fluctuations caused by the solar constant are sufficiently damped.
Technical Paper

Air / Foam Insulation for a Freezer in μg Conditions–Trade-Off, Analysis and On-Earth Verification

2001-07-09
2001-01-2290
This paper shows the results obtained after the development of the thermal insulation concept described in [1] and used for freezers and coolers in manned spacecraft submitted to micro-gravity environment. The use of foam walls for space refrigerators have some disadvantages: mass, flammability and toxicity. The BIOLAB (European Biology Laboratory of board International Space Station, ISS) facility is equipped with two thermal conditioning units (TCU) whose housing consist of hollow carbon fiber reinforced plastic (CFRP) walls. This technology reduces the mass of each one by 20%, and the development cost, when compared with foam wall insulation (4Kg over a total of 20Kg). This paper describes the design of the hollow solution and presents the results of the analysis and test that were done. The test and analysis protocol used to validate the finite element model (FEM) and the simulation of the performances on orbit is presented as well.
Technical Paper

The Thermal Control Concept of the Mars Netlander Surface Module

2001-07-09
2001-01-2282
The Netlander mission aims to deploying on the surface of Mars a network of 4 landers, which will perform simultaneously measurements in order to study the internal structure of Mars, its sub-surface and its atmosphere. This paper describes the phase B thermal control concept of the Netlander Surface Module, taking into account various thermal environments from the cruise to Mars phase until the landing and the one Martian year phase on the Mars surface. The paper focuses on two specific thermal tests. The first one is a thermal conductivity measurement of three pre-selected insulation materials in a 6 - 10 hPa CO2 environment, and the second one is a performance test of a Loop Heat Pipe designed to comply the Netlander Surface Module needs. This paper is mainly derived from the report referenced ref. 1.
Technical Paper

Specular Reflection Allowing Reduction and Calculation of Radiative Heat Transfer

2001-07-09
2001-01-2438
Configurations similar to ’V-Grooves’, as already applied for radiators, can also insulate complete spacecraft and telescopes from solar radiation or hot modules several orders of magnitude better than the usual MLI. The specularity of surfaces contributes to the reduction of the radiation between the shields and thus improves the insulation. In this paper absorption factors between specularly and diffusely reflecting conical and rectangular areas are presented versus the ’V-angle’ in order to design such insulating configurations. Monte Carlo methods cannot be applied for very complex configurations if the number of surfaces is too large. The introduction of auxiliary areas with 100% specular reflectivity helps to simplify these geometries. Herein, the principle of this technique is first explained and proven by two examples of V-grooves. Then this method is applied for a specific configuration: three parallel plates which each have more than 8000 holes.
Technical Paper

Windtunnel Catalyticity Evaluation for Thermoprotective Elements

2001-07-09
2001-01-2384
22 Flexible External Insulation (FEI) Blankets of various types were subjected to a plasma aging in simulated reentry conditions in TsAGI’s VAT-104 windtunnel in the frame of 4 test campaigns on FEI characterization. Blankets were tested at top side temperature Tw =800…1200°C during 60 min each. Widespread numerical simulation of the test conditions and the model heating was performed using full Navier-Stokes equations. FEI catalyticity obtained from correlation between measured and calculated heat fluxes is Kw=1…10m/s.
Technical Paper

Detecting and Extinguishing of Arcs in Aircraft Electrical Systems

2001-09-11
2001-01-2657
Arcing conditions in aircraft electrical systems, in cable insulations that contain polyimid may cause explosive burning of the sheathed cable and surrounding materials due to the chemical structure of this insulation material. Alternating current arcs exhibit a typical gap of the current flow. Test procedures have been established and they are the platform upon which existing and future developments and standards for arc fault detectors will be based. First generation devices detect arcs only upon their appearance because of their characteristic features whether in the time- and/or frequency domain. The biggest challenge is to differentiate between “normal” interference signals and arcs and to meet the desired critical physical dimensions. An ideal solution would be to detect failures of insulation defects prior to the appearance of an energetic arc and at the same time identifying the location of the fault.
Technical Paper

New Developments in Molded Polyurethane for Sound Insulation Applications

2001-04-30
2001-01-1555
The continual trend towards weight reduction resulted in the implementation of molded polyurethane carpet underlay at a density of 43 kg/m3 in early 2000. Now, through new formulation developments, coupled with the production introduction of carbon dioxide co-blown technology, additional weight reductions have been achieved. This has resulted in molded densities of 34 kg/m3 to be reached in prototype moldings. In addition to weight reductions, there has also been a renewed focus on improving the acoustical performance of the sound insulation material. As a result, a new family of formulations has been developed which have shown acoustical improvement while not sacrificing weight. This paper will showcase these new developments and highlight the benefits of polyurethane in sound insulation applications.
Technical Paper

1D Unsteady Flows with Chemical Reactions in the Exhaust Duct-System of S.I. Engines: Predictions and Experiments

2001-03-05
2001-01-0939
This paper describes some recent advances of the research work concerning the 1D fluid dynamic modeling of unsteady reacting flows in s.i. engine pipe-systems, including pre-catalysts and main catalysts. The numerical model GASDYN developed in previous work has been further enhanced to enable the simulation of the catalyst. The main chemical reactions occurring in the wash-coat have been accounted in the model, considering the mass transfer between gas and solid phase. The oxidation of CO, C3H6, C3H8, H2 and reduction of NO, the steam-reforming reactions of C3H6, C3H8, the water-gas shift reaction of CO have been considered. Moreover, an oxygen-storage sub-model has been introduced, to account for the behavior of Cerium oxides. A detailed thermal model of the converter takes into account the heat released by the exothermic reactions as a source term in the heat transfer equations. The influence of the insulating mat is accounted.
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