Criteria

Text:
Display:

Results

Viewing 164461 to 164490 of 188470
1972-02-01
Technical Paper
720507
J. D. Shedlowsky
In its treatment of acoustical leaks in passenger car bodies, this paper considers the general principle of noise control in a passenger compartment, the concept of acoustical leaks, examples of such leaks, and design guidelines for acoustical isolation. The paper states that the basic problems can actually be designed into vehicles through lack of understanding of acoustical principle, and various examples are given in illustration. Remedies for some of these deficiences are also proposed. Finally, design principles formulated to eliminate acoustic leaks are presented.
1972-02-01
Technical Paper
720672
E. N. Cantwell, E. S. Jacobs, W. G. Kunz, V. E. Liberi
Exhaust particulate lead trapping systems and devices designed to reduce airborne lead emissions by 65 percent or more have been developed and tested on vehicles. Tests of up to 60,000 miles indicate that these devices should retain their effectiveness and last the lifetime of a passenger vehicle without maintenance. The traps reduced the total amount of lead emitted from production vehicles operated on leaded gasoline by 82 to 91 percent. They also reduced by 64 to 84 percent the amount of lead in the air after driving both production and trap-equipped vehicles through a vehicular tunnel. When a trapping system was combined with a gaseous emission control system, consisting of exhaust manifold thermal reactor and exhaust gas recirculation systems, the total lead emitted was reduced by 85 percent and the amount of lead found in the air of the vehicular tunnel was reduced by 71 percent when compared with production vehicles.
1972-02-01
Technical Paper
720670
Marc S. Newkirk, James L. Abel
International Materials undertook to develop an inherently low-polluting automobile, the “Boston Car,”* with two fixed design parameters: the use of an internal combustion engine and the use of gasoline fuel. On-board production of carbon dioxide-hydrogen mixtures to fuel the engine was the approach undertaken; gasoline was reacted with steam to produce a “reformed” fuel upstream from the engine. Initial efforts to develop an engine to burn the mixture revealed problems with respect to starting reliability and high rpm carburetor flashback. Starting reliability was achieved by providing accurate air/fuel ratios at cranking speeds. It was necessary to employ a spark distributor lacking any provisions for spark advance in order to guarantee elimination of flashback at advanced rpms. These modifications have resulted in extremely fine road performance from the test vehicle, comparable to the production model prior to modification.
1972-02-01
Technical Paper
720661
Robert U. Ayres
The basis for formulating so-called “uniform” emission standards for motor vehicles is examined and found to be inconsistent with the widely accepted principle that “the polluter should pay,” if consideration is given to the problems caused by pollution rather than the sources of emissions. Atmospheric pollution problems are geographically limited and also depend upon other variables such as time of day, and weather conditions. The major problems are associated with Southern California and other cities of the southwest, and congested urban areas. It is proposed that emissions standards should be made flexible in order to reflect these environmental variations, and thus to achieve the maximum environmental improvement for the least total cost to vehicle owners and users.
1972-02-01
Technical Paper
720644
E. J. Croke, K. G. Croke, J. E. Norco
The significance of the impact of transportation system characteristics on the urban quality has resulted in a need to evaluate certain transportation air quality-oriented policy statements regarding the effect of present efforts to reduce emissions from automobile operation or to design transportation systems that do not constitute a danger to air quality. The evaluation of these policies requires the integration of planning techniques from both transportation and environmental fields. The classical transportation system planning process involves a well-established sequence of data acquisition and systems analysis activities. Likewise, the regional air pollution planning procedures also depend on the use of a sequence of empirical models that require a substantial data base.
1972-02-01
Technical Paper
720623
Theodore Berland
Trucks are the major source of noise on our streets and highways, affecting the sleep and sanity of millions of city and suburban residents. Truck noise sources are many, but mainly are engine and tires. Since the automotive and trucking industries have not volunteered to quiet truck noises, the Federal government will have to legally require they do so.
1972-02-01
Technical Paper
720621
William B. Becker
United States airlines are deeply concerned about the problem of aircraft noise, and have been actively involved in developing methods of abatement. There are three basic approaches that may be taken to handle this problem: reduction of noise at the source, operational procedures, and control of land use in the vicinity of airports. Aircraft noise is a problem that will be solved only through massive cooperative effort and federal funding. And it should be remembered in any suggested solutions that maintenance of the highest safety standards must be the overriding consideration.
1972-02-01
Technical Paper
720622
Lloyd Hinton
The history of the aircraft noise problem is presented using many references to particularly important studies. Emphasis is placed upon the similarity of expert opinions during twenty years of research for measures needed to resolve the problem. While objectivity is sought -- the common denominator of the aircraft noise issue is controversy -- the author is representing the views of noise impacted airport community residents who cannot comprehend the lack of progress in aircraft noise abatement. This lack of progress has persisted in spite of general agreement on measures needed and is the basis of a call for the reallocation of authority among federal agencies having responsibility both for the regulation of aviation and for the planning and development of urban areas -- including airports -- with environmental protection as basic criterion.
1972-02-01
Technical Paper
720619
David V. Ragone
Universities, in the process of pursuing their classical roles, the generation and dissemination of knowledge, can contribute significantly to the resolution of automotive air pollution problems if they recognize problem-oriented, as well as discipline-oriented approaches to education. In addition to the classical roles, both faculty and students can contribute as unbiased, but informed, third parties who can validate technical arguments in controversial areas for the public.
1972-02-01
Technical Paper
720617
J. C. Ellis
The national concern over air quality and the understanding of the role of the internal combustion engine powered passenger car as a contributor of atmospheric pollutants has imposed new design criteria upon both the automobile manufacturer and the petroleum refiner. For the passenger car engine builder these criteria have been specified by the emission standards required by the Clean Air Amendments of 1970. With certain exceptions, gasolines for these low-emitting passenger cars have not yet been specified nor have their required quality and performance characteristics been clearly spelled out. This paper attempts to judge the influence of emission control requirements on future gasoline quality. Lead anti-knocks, hydrocarbon compositions and gross physical properties are among the factors considered and an effort is made to quantify the effects of changes in these characteristics on emissions and to estimate their impact on the industry.
1972-02-01
Technical Paper
720616
John J. Brogan
The Clean Air Act Amendments of 1970 require that new model automobiles of 1976 and later meet stringent exhaust emission standards. The technical difficulties appearing in ‘Clean-up’ of the conventional automobile engine require that alternate engines be developed in the event that the conventional engine cannot be made to meet the standards. Although the alternates cannot be mass produced by 1976, prototype engine development and demonstration by that date may lead to decisions to mass produce one or more in the early eighties. Features of the major alternate engine systems are reviewed, projections are made of the prospects of each as a replacement for the conventional engine. The introduction to production of rotary Otto cycle systems by the mid-1970's, gas turbines by the early 1980's and high performance all-electric systems by the late 1980's is projected in this paper.
1972-02-01
Technical Paper
720612
William T. Westfield
An afterburning turbofan engine was operated over a range of simulated altitudes and Mach numbers to determine if correlation existed between static sea level emissions and those at altitudes and flight speeds. Data were taken at a point about 27 feet downstream of the exhaust nozzle exit and on the centerline of flow. No apparent effect of altitude or flight speed on emissions, either gaseous or particle, was observed.
1972-02-01
Technical Paper
720615
Albert G. Lucas, George W. Niepoth
The present spark ignition, reciprocating piston, gasoline engine is examined against the basic requirements for an automotive powerplant. The important requirement of emission control is shown to affect these basic requirements. The emission potential of this engine and the prospect of reducing its emissions to an acceptable level are explored. The effect of these factors on future gasoline engines is discussed.
1972-02-01
Technical Paper
720609
R. D. Henderson
This paper comments on the status of emission regulations; provides estimates of emissions from earthmoving vehicles based on Caterpillar information and compares this with diesel powered off-highway machinery based on Bureau of Mines data; suggests that simple emission test procedures may suffice for the great variety of equipment used in the construction industry if standards are established; and proposes that non-productive testing to prove conformance to standards be minimized.
1972-02-01
Technical Paper
720610
Melvin Platt, E. Karl Bastress
Aircraft emissions and their impact upon air quality have been studied at four major air carrier airports and two general aviation airports. Predicted concentrations of non-methane hydrocarbons and carbon monoxide, due to aircraft emissions alone, have been found to exceed their respective national ambient air quality standards. In the case of nitrogen dioxide, aircraft emissions contribute significantly to excessive concentrations. On the other hand, aircraft contributions to excessive concentrations of particulates and sulfur dioxide are small in areas to which the public has “reasonable access.”
1972-02-01
Technical Paper
720839
W. Sanscrainte, M. Chazen
The requirements of the Space Shuttle Bipropellant RCS Engine Technology contract and the scheduled contract effort are presented herein. The requirements included an engine concept scalable from 400 to 1100 lbf, with a 100 mission life employing N204/MMH propellants. Emphasis is placed on reusability and minimum post-flight servicing. The engine components are reviewed and their selection supported by tradeoff analyses, thrust chamber firing test data, materials test data and metallurgical evaluations. The materials test data indicate that the proposed silicide-coated columbium chamber and uncoated columbium injector have the potential of meeting the mission life consistent with the Isp goals. The engine valve trade studies resulted in the selection of a torque motor-operated bipropellant valve configuration.
1972-02-01
Technical Paper
720607
Robert E. Field
The ecology of our environment has recently been of great concern to all of us. In the bus business, we have gone from horse drawn carriages, to electric, to steam power to diesel power to obtain an efficient, clean operating vehicle. A great deal of effort has been expended in determining the components of the emissions of the diesel engine. Great strides have been made in reducing these emissions. GMC Truck & Coach has developed and released an Environmental Improvement Program that reduces smoke to the invisible range and meets Federal standards for HC, CO and NOx. Odor also is eliminated as a problem.
1972-02-01
Technical Paper
720827
Norman L. Tangedal
Solar gas turbines have been used in a large variety of applications. This paper reviews some of the innovative, industrial-type applications in which these turbines have successfully performed.
1972-02-01
Technical Paper
720834
R. D. Marcy, J. P. Maddox
The performance, mechanical integrity, and operational characteristics of a monopropellant thermal gas generator have been predicted using analytical tools developed through the use of digital and analog computer programs. The basis for these analyses are empirical relationships derived from experiments, as well as theoretical relations. A throttleable prototype gas generator has been designed and fabricated to meet the requirements of an APU for use in the Space Shuttle vehicle.
1972-02-01
Technical Paper
720825
Robert Harnsberger
The application of jet gas turbines to industrial uses of all types has been a successful venture in its short history of 12 years. Through this effort, aircraft technologies and practices have been found to blend well to the requirements of the stationary ground-based gas turbine. For those unfamiliar with the subject, the paper presents an overview of the jet gas turbine as an industrial product, the applications and gas generator models involved in this activity, and the maintenance concept, which is unique in the industry.
1972-02-01
Technical Paper
720826
G. M. Boatwright
The primary purpose of this paper is to describe the application of two Aero derivative gas turbine engines to the DD963 Spruance Class of Destroyers. Some of the effects of these applications on other portions of the ship, on training, on maintenance, and other logistics will be discussed. Also, several other proposed shipbuilding programs expected to use gas turbine propulsion are mentioned.
1972-02-01
Technical Paper
720837
Thomas F. Schweickert
Rocket propulsion systems for reusable vehicles will be required to operate reliably for a large number of missions with a minimum of maintenance and a fast turnaround. For the space shuttle reaction control system to meet these requirements, current and prior related system failures were examined for their impact on reuse and, where warranted, component design and/or system configuration changes were defined for improving system service life. It was found necessary to change the pressurization component arrangement used on many single-use applications in order to eliminate a prevalent check valve failure mode and to incorporate redundant expulsion capability in propellant tank designs to achieve the necessary system reliability. Conceptual designs were developed to show how each of these provisions might be implemented.
1972-02-01
Technical Paper
720838
William J. O'Brien
The Space Shuttle Orbiter is a combination spacecraft and aircraft which can remain in orbit from 7 to 30 d and also fly horizontally and land on existing commercial airport runways. The vehicle utilizes gimballing of the main rocket engines for control during ascent and typical aerodynamic surfaces for control during reentry, approach, and landing. A hydraulic system was selected as the power source for operation of these controls and for actuation of the landing gear, brakes, steering, and jet engine deployment. This paper discusses the system selection rationale, power requirements, flight control characteristics, operational profile, maintenance features, built-in test requirements, and innovative features of the hydraulic system. The system design provides for spacecraft reliability with commercial aircraft serviceability.
1972-02-01
Technical Paper
720835
W. L. Burriss, B. H. Rowlett
The two major factors that affect auxiliary power system design decisions are: the working fluid to be used, and vehicle mission requirements. It has been found that optimum turbine designs will be similar for the two working fluids (hydrazine or hydrogen-oxygen) considered for the shuttle orbiter system due to the constraints imposed by geometrical and mechanical design limitations. As a consequence, variations in power level and/or working fluid selection can be efficiently accommodated by relatively minor modifications to turbine nozzle design. Analytical techniques for optimization of turbine aerodynamic design parameters have been developed. These techniques can be extended to include transient-state simulation and design optimization of the other system components, including the turbine controller, in a manner similar to that used for development of control systems for multi-spool fan-jet engines.
1972-02-01
Technical Paper
720836
D.A. Straznickas, J.M. Preble, D.B. Wigmore
The effects of system/component selection and design on the fuel consumption of a hydrazine fueled, auxiliary power unit suitable for the Space Shuttle Orbiter are discussed. An auxiliary power unit (APU) output of 150 HP hydraulic and 20 KVA electrical has been assumed as well as a representative load/altitude mission profile. While the efficiency of the various components which make up the system are discussed, emphasis is placed on turbine and control system design as these areas are major contributors to APU performance.
1972-02-01
Technical Paper
720085
Jack D. Benson
Engine after-run, sometimes referred to as “run-on” or “dieseling,” has existed for many years, but seems to be occurring more frequently with late-model cars and low-octane gasolines. A vehicle study was conducted to gain a better understanding of the factors that influence after-run. Engine operating variables, such as high idle speed, lean idle mixture, and retarded basic spark timing, all increased after-run frequency by increasing the throttle opening (intake charge density). Reduced Research-octane number of the gasoline also increased after-run frequency, but Motor-octane number and hydrocarbon composition did not have any effect. After-run exhaust contained about 125 times more aldehydes than engine idle exhaust, and it caused eye irritation and an obnoxious odor. Compression ignition, rather than surface ignition, is most likely the cause of after-run.
1972-02-01
Technical Paper
720093
Albert L. Klosterman
Powerful capabilities for use in the analysis of complex automotive systems have recently been developed. These capabilities bring the newly developed electronic testing equipment together with the powerful computational techniques to perform a total system dynamic design analysis. The analysis tool developed is called the building block approach, whereby complex system behavior is defined by analyzing and combining the dynamic behavior of simpler components and subassemblies. The dynamic behavior of each component is obtained from a separate analytical investigation or from a specific type of experimental test procedure. Component data are then combined mathematically to predict dynamic behavior of the full system under the prescribed loading conditions. With the system simulation completed, design changes in any or all components can be evaluated. The effect of changes in any component on the operating behavior, vibration, noise, and stress can be ascertained.
1972-02-01
Technical Paper
720102
I. M. Khan, C. H. T. Wang, B. E. Langridge
This paper describes and discusses the results obtained from tests of the effect of air swirl variations on smoke and gaseous emissions from direct-injection-type diesel engines. Within the limits of the swirl variations used, an increase in swirl reduced emissions of smoke and carbon monoxide but increased nitric oxide emissions. An increase in swirl also makes it possible to retard appreciably the injection timing for optimum engine efficiency, and this more than compensates for the increase in nitric oxide emission due to the increase in swirl. It is also shown that the air swirl intervenes in the processes of smoke and gaseous pollutant formation by affecting the details of the fuel-air mixing processes.
1972-02-01
Technical Paper
720104
J. M. Perez, L. C. Broering, John H. Johnson
A Coordinating Research Council cooperative program was conducted to evaluate the measurement methods used to analyze nitric oxide and carbon monoxide in diesel exhaust. Initially, a single-cylinder test engine was circulated among participants with poor results. Tests were then conducted at one site using a multicylinder diesel engine. Six organizations participated in the program. Exhaust analyses were conducted at steady-state engine conditions and on a 3 min cycle test. Span gases of unknown concentration were also analyzed. The participants results varied but averaged less than ±5% standard deviation both within (repeatability) and among (reproducibility) the instruments. The short cycle test was in good agreement with the steady-state measurements. No significant difference in the use of Drierite, nonindicating Drierite, or Aquasorb desiccants was evident in sampling system tests.
1972-02-01
Technical Paper
720111
Baruch Berman, George H. Gelb
Proper selection of the traction drive system to meet the requirements of an electric passenger vehicle is of prime importance. Choice may be made among alternating current, direct current or combined systems. Each approach can be implemented by utilizing various control techniques and power elements. For instance, an AC system may use an adjustable voltage inverter (AVI) or a pulse-width-modulated inverter (PWMI) for the power processor; and an induction motor or a synchronous motor for the rotating element. Similar alternatives exist for a DC system. The choice of a suitable manner of implementation must be based on information characterizing the various elements and tradeoffs matching them to the vehicle requirements. This paper describes various AC and DC techniques, characterizes AVI, PWM and representative DC chopper power processors and examines their interface with a variety of motors such as series, shunt, induction, etc.

Filter

  • Range:
    to:
  • Year: