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Technical Paper

2-Color Thermometry Experiments and High-Speed Imaging of Multi-Mode Diesel Engine Combustion

2005-10-24
2005-01-3842
Although in-cylinder optical diagnostics have provided significant understanding of conventional diesel combustion, most alternative combustion strategies have not yet been explored to the same extent. In an effort to build the knowledge base for alternative low-temperature combustion strategies, this paper presents a comparison of three alternative low-temperature combustion strategies to two high-temperature conventional diesel combustion conditions. The baseline conditions, representative of conventional high-temperature diesel combustion, have either a short or a long ignition delay. The other three conditions are representative of some alternative combustion strategies, employing significant charge-gas dilution along with either early or late fuel injection, or a combination of both (double-injection).
Technical Paper

2-D Measurements of the Liquid Phase Temperature in Fuel Sprays

1995-02-01
950461
Cross-sectional distributions of the liquid phase temperatures in fuel sprays were measured using a laser-induced fluorescence technique. The liquid fuel (n-hexadecane or squalane) was doped with pyrene(C16H10). The fluorescence intensity ratios of the pyrene monomer and excimer emissions has temperature dependence, and were used to determine the liquid phase temperatures in the fuel sprays. The measurements were performed on two kinds of sprays. One was performed on pre-heated fuel sprays injected into surrounding gas at atmospheric conditions. The other was performed on fuel sprays exposed to hot gas flow. The spray was excited by laser radiation at 266nm, and the resulting fluorescence was imaged by an intensified CCD camera. The cross-sectional distribution of the liquid phase temperature was estimated from the fluorescence image by the temperature dependence of the intensity ratio.
Book

2009 Ultimate GD&T Pocket Guide 2nd Ed

2017-03-27
The Ultimate GD&T Pocket Guide explains the most common rules, symbols, and concepts used in geometric dimensioning and tolerancing. ...This one-of-a-kind reference guide includes over 100 detailed drawings to illustrate concepts, more than 40 charts for quick reference, explanations of each GD&T symbol and modifier and much more...Written by standards expert Alex Krulikowski, this valuable on-the-job reference clarifies how to interpret standard-compliant technical drawings that use ASME Y14.5-2009.
Technical Paper

21st Century Lunar Exploration: Advanced Radiation Exposure Assessment

2006-07-17
2006-01-2106
On January 14, 2004 President George W Bush outlined a new vision for NASA that has humans venturing back to the moon by 2020. With this ambitious goal, new tools and models have been developed to help define and predict the amount of space radiation astronauts will be exposed to during transit and habitation on the moon. A representative scenario is used that includes a trajectory from LEO to a Lunar Base, and simplified CAD models for the transit and habitat structures. For this study galactic cosmic rays, solar proton events, and trapped electron and proton environments are simulated using new dynamic environment models to generate energetic electron, and light and heavy ion fluences. Detailed calculations are presented to assess the human exposure for transit segments and surface stays.
Technical Paper

3-Dimensional Lightning Observations Using a Time-of-Arrival Lightning Mapping System

2001-09-11
2001-01-2881
A lightning mapping system has been developed that locates the sources of VHF radiation from lightning discharges in three spatial dimensions and time. The system consists of several VHF receivers distributed over an area of about 100 km diameter. The system locates VHF radiation sources over the array with an accuracy of about 100 m. The system locates sources out to 250 km from the center of the array with reduced accuracy. The observations are found to reflect the basic charge structure of electrified storms.
Standard

400 Hz CONNECTION AIRCRAFT ELECTRICAL MAINTENANCE PROCEDURES

1994-12-01
HISTORICAL
AIR4365
This SAE Aerospace Information Report (AIR) describes field-level procedures to determine if 400 Hz electrical connections for external power may have been subjected to excessive wear, which may result in inadequate disengagement forces.
Technical Paper

4300 F Thermocouples for Re-Entry Vehicle Applications Part II

1963-01-01
630360
This paper presents a discussion of the component evaluation and design development work performed in developing a 4300 F reentry vehicle nose cap temperature sensor. Material compatabilities, insulation resistance, and atmospheric pressure effects on bare wire calibration data are discussed in some detail. The final design is outlined and the application problems discussed. The probe utilizes: a sintered iridium high temperature sheath (4300 F) and platinum 20% rhodium as the low temperature sheath (3000 F); beryllia as insulation -- hard fired at 4300 F and compacted powder at 3000 F; tungsten versus tungsten 26% rhenium as the thermocouple pair.
Technical Paper

56 Development of two-cylinder liquid-cooled utility gasoline engine models with twin balancer shafts

2002-10-29
2002-32-1825
The new small and lightweight 2-cylinder liquid-cooled OHC gasoline engines were developed. These new engines are featuring high output, low vibration and noise radiation and so able to improve the comfortableness and amenity of applied utility machines. In this paper, the features of the new engines and the process to realize development targets are introduced. The basic structure adopted on the new engines is a liquid-cooled, inline 2-cyilinder layout with 360-degree firing intervals, twin balancer shafts, and an overhead camshaft that is driven by a cogged belt. Also various parts made of aluminum alloy and plastics could make the engine lighter. By these measures, the new engines could satisfy their hardest development targets, and realize their easy installation, higher versatility, and have the excellent features such as compact size, lightweight, high output, low exhaust gas emission and low vibration and noise radiation.
Technical Paper

A 3D Simulation Methodology for Predicting the Effects of Blasts on a Vehicle Body

2019-04-02
2019-01-1033
Triggered explosions are increasingly becoming common in the world today leading to the loss of precious lives under the most unexpected circumstances. In most scenarios, ordinary citizens are the targets of such attacks, making it essential to design countermeasures in open areas as well as in mobility systems to minimize the destructive effects of such explosive-induced blasts. It would be rather difficult and to an extent risky to carry out physical experiments mimicking blasts in real world scenarios. In terms of mechanics, the problem is essentially one of fluid-structure interaction in which pressure waves in the surrounding air are generated by detonating an explosive charge which then have the potential to cause severe damage to any obstacle on the path of these high-energy waves.
Technical Paper

A Boundary Element Formulation for Acoustic Radiation from Axisymmetric Components with Arbitrary Boundary Conditions

1991-11-01
912609
This paper presents a computational technique using Boundary Element method for the prediction of sound radiated by axisymmetric bodies with arbitrary boundary conditions. By taking the advantage of the axisymmetric property of the body the three dimensional integral formulation is reduced to one dimensional integral along the generator of the body. The arbitrary boundary conditions is expanded in Fourier series with a period of 2π. The integral equation is solved using superposition principle involving each term of the series. By adding the result associated with each term the final solution is obtained. A numerical procedure is implemented using curvilinear isoparametric element representatation. Examples are given involving an oscillating sphere and a half vibrating sphere. The results are compared with the analytical solution in which good agreement has been obtained.
Technical Paper

A Canopy Model for Plant Growth Within a Growth Chamber: Mass and Radiation Balance for the Above Ground Portion

1991-07-01
911494
As humans move into outer space, need for air, clean water and food require that green plants be grown within all planetary colonies. The complexities of ecosystems require a sophisticated understanding of the interactions between the atmosphere, all nutrients, and life forms. While many experiments must be done to find the relationships between mass flows and chemical/energy transformations, it seems necessary to develop generalized models to understand the limitations of plant growth. Therefore, it is critical to have a robust modelling capability to provide insight into potential problems as well as to direct efficient experimentation. Last year we reported on a simple leaf model which focused upon the mass transfer of gases, radiation/heat balances, and the production of photosynthetically produced carbohydrate. That model indicated some of the plant processes which had to be understood in order to obtain parameters specific for each species.
Technical Paper

A Case Study on Road Noise Source Identification and Reduction Measures in a Compact SUV

2017-06-05
2017-01-1863
Road noise and speech intelligibility are becoming ever more important, irrespective of the vehicle size, due to vehicle refinement as well as connectivity with mobile communication equipment. With better aerodynamic designs, development of refined powertrains, and a tectonic shift from I.C. engine to electric motors, road noise and wind noise will become more apparent to the customer and hence will become a priority for automakers to refine their vehicles. This paper describes the efforts undertaken to identify the road noise paths and develop countermeasures for a compact SUV vehicle. A hybrid test/CAE approach was followed to improve road noise performance of this vehicle. This effort involved developing tire CAE models from physical hardware and creating synthesized road-load input from data taken on roads.
Technical Paper

A Combat Vehicle Gun Fire Simulator for Analyzing Crew Shock Loading

2005-04-11
2005-01-1409
This paper describes a system which includes several subsystems forming a gun recoil injury-monitoring simulator. These subsystems include: a motion simulator, motion capture system, mannequin with integrated data acquisition, and combat vehicle dynamics model. Motion data from these subsystems provides vehicle and human factors engineers with valuable information about the occupant response to gun fire events. The final system has been successfully utilized recently on a gun fire program that enabled vehicle designers to determine results of their concept design. The simulation design exceeded performance expectations and can be used on future vehicle design iterations.
Technical Paper

A Combustion Products Analyzer for Contingency Use During Thermodegradation Events on Spacecraft

1991-07-01
911479
As mission length and the number and complexity of payload experiments increase, so does the probability of thermodegradation contingencies (e.g. fire, chemical release and/or smoke from overheated components or burning materials), which could affect mission success. When a thermodegradation event occurs on board a spacecraft, potentially hazardous levels of toxic gases could be released into the internal atmosphere. Experiences on board the Space Shuttle have clearly demonstrated the possibility of small thermodegradation events occurring during even relatively short missions. This paper will describe the Combustion Products Analyzer (CPA), which is being developed under the direction of the Toxicology Laboratory at Johnson Space Center to provide necessary data on air quality in the Shuttle following a thermodegradation incident.
Technical Paper

A Comparison of MAFIA / Microwave Studio Calculations with Experimental Results for Indirect Lightning Effects on Carbon Composite Structures

2001-09-11
2001-01-2886
A study of indirect lightning effects on carbon composite structures with internal tubing is performed using the ‘ab initio’ Maxwell equation codes MAFIA and Microwave Studio (MWS). The modeling is performed both in the time and frequency domain by a finite difference method that can accommodate anisotropic media. Both time and frequency domains are used to better reflect the actual testing performed on aircraft. Solutions in frequency domain also help to overcome limitations of the time domain calculations. Time calculations cannot be performed for pulses longer than 100–200 μs due to the Courant condition and computer time limitations and hence, low frequency resonances of the system could be missed. Three dimensional frequency domain calculations are available with MAFIA and MWS, while time domain results are available in MAFIA, MWS and EMA3D.
Technical Paper

A Comparison of Numerical Techniques for the Study of Lightning Indirect Effects

2001-09-11
2001-01-2894
A comparison of various numerical tools and techniques was performed for calculating the lightning indirect effects to composite structures and internal systems. This paper is a summary of the initial comparison results. Detailed results of each technique considered are given in additional separate papers presented during this conference. The modeling considered current distributions over and within composite surfaces and the coupling of current and voltages to internal systems such as wire bundle cables and hydraulic and fuel tubes. The models were compared to each other and to measured data from low level swept continuous wave (LLCW) tests performed on two test fixtures. Other features of the codes such as run time, ease of use, computer requirements, availability of documentation and technical support, etc. are compared as well.
Journal Article

A Comparison of Various Fire Detection Methodologies in Transit Vehicle Engine Compartment Fire Protection Systems

2012-04-16
2012-01-0983
Distinctly different fire hazards exist within the engine compartment of a transit vehicle and various detection methodologies may be employed to detect fire events arising from these hazards. The engine compartment presents a particularly challenging environment and it is important to select the correct methodology to ensure timely detection response in the early stages of the development of a fire whilst minimizing nuisance alarms. The choice of the correct detection methodology for a specific fire hazard is therefore determined by the suitability of the methodology for the detection of the anticipated fire event within the environment in which it is required to operate. This paper presents experimental data to demonstrate the variation in the response times of different detection methodologies in the presence of common fire events in the form of simulated flaming fuel fires and a simulated electrical fault in the form of an overheated electrical cable.
Technical Paper

A Comparison of Worldwide Fuels and their Effects on Combustion under Constant Volume Vessel Conditions

2015-09-01
2015-01-1919
Worldwide diesel fuels differ in their composition and therefore in thermo-physical properties. Some of these properties are known to have little effect on the combustion process. Others, like the cetane number, have dramatic influence on the combustion formation and thus on the heat release rate and more important the formation of soot and NOx. In an experiment series various commercially available fuel types, like EN 590 [1], ASTM D975 [2] and JIS K 2204 [3], have been compared to alternative diesel fuels such as FAME, GtL and premium diesel fuel with increased cetane number. A specially designed research injector was used in order to provide full optical access to one single fuel jet injected and combusted in a constant volume vessel. First, the liquid fuel phase propagation has been investigated by means of Mie-scattering and the liquid penetration depth and the spray cone angle have been evaluated.
Technical Paper

A Comparison of the Entropy of Thermal Radiation to that of Heat Conduction

1999-08-02
1999-01-2672
Many thermodynamic texts imply that the entropy flux for thermal radiation (TR) is the same as that for heat conduction, the heat flux divided by the local temperature (q/T). However, for blackbody radiation (BR) emission a 4/3 coefficient occurs and recently it was shown that for non-blackbody radiation (NBR) the coefficient is greater than 4/3 [1]. Some of the fundamental equations that are used in thermodynamics express the entropy flux of heat transfer in a q/T type form. In this paper we address the use of the Clausius equality, and expressions extended from it for irreversible processes, when TR is involved. We find that the Clausius equality for reversible processes is applicable, while the statements extended for irreversible processes are not applicable. Also, we present an alternative derivation of the 4/3 coefficient that shows in a direct way that it follows from the observable relation between BR energy and emission temperature (i.e., energy is proportional to T4).
Technical Paper

A Comparison of the Prediction of Lightning Indirect Effects Using 2-D Analytical Tools with Measured Data from Two Composite Test Fixtures

2001-09-11
2001-01-2904
A comparison was done of the prediction capabilities for lightning indirect effects of two two-dimensional (2-D) computer codes using two graphite structural test fixtures. The two codes evaluated were an internal Boeing Method-of-Moments code and a commercially available Boundary Element method code. The codes were compared against each other and against test data. The purpose was to evaluate the prediction capabilities of both codes for use in predicting lightning indirect effects on internal components of graphite structure. Since 2-D codes are much easier to use than 3-D codes, they could be widely used in trade studies and design evaluations for lightning indirect effects protection of composite aircraft. The first code, REDIST, is a Method-of-Moments code developed in the 1980’s for use on the B-2. The REDIST code has short run times and is somewhat easier to use than the second code that was investigated.
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