Engineering topics

Cooper, L. P.

Publications and source records attributed to Cooper, L. P..

31 records · Page 2

NASA NTRS1984

Propulsion issues for advanced orbit transfer vehicles

Studies of the United States Space Transportation System show that in the mid to late 1990s expanded capabilities for orbital transfer vehicles (OTV) will be needed to meet increased payload requirements for transporting materials and possibly men to geosynchronous orbit. Discussion and observations relative to the propulsion system issues of space basing, aeroassist compatibility, man ratability and enhanced payload delivery capability are presented. These issues will require resolution prior to the development of a propulsion system for the advanced OTV. The NASA program in support of advanced propulsion for an OTV is briefly described along with conceptual engine design characteristics.

Cooper, L. P.↗

NASA NTRS1983

OSHA medical and workplace surveillance requirements and NIOSH recommendations (for employees exposed to toxic substances and other work hazards)

Both OSHA medical and work place surveillance requirements and NIOSH recommendations were prepared as a desk reference to help occupational health professionals to perform their duties. The medical surveillance information focuses on frequency of physical examinations, specific problems that may arise as a result of exposure (e.g., decreased immunocompetence, weight loss, ets.), conditions that intensify the harmful effects of exposure (e.g., medication an exposed employee may be taking, cigarette smoking, etc.), the areas that should be scrutinized in medical and work histories and during the physical exam, and specific clinical tests that should be conducted. Recordkeeping requirements are also specified. The workplace surveillance information consists of monitoring requirements, personal protective equipment requirements, and recordkeeping requirements. Such details as the sampling devices that should be used, the type of respirators that should be worn, and the frequency of inspections are included. This document does not specify the training, labeling and posting, and safe work practice requirements and recommendations due to space considerations.

Cooper, L. P.↗

NASA NTRS1983

Advanced propulsion concepts for orbital transfer vehicles

Studies of the United States Space Transportation System show that in the mid-to-late 1990s expanded capabilities for Orbital Transfer Vehicles (OTV) will be needed to meet increased payload requirements for transporting materials and possible men to geosynchronous orbit. NASA is conducting a technology program in support of an advanced propulsion system for future OTVs. This program is briefly described with results to date of the first program element, the Conceptual Design and Technology Definition studies. Previously announced in STAR as N83-26924

Cooper, L. P.↗

NASA NTRS1982

Advanced propulsion concepts for orbital transfer vehicles

Cooper, L. P.↗

NASA NTRS1981

Analysis of effect of flameholder characteristics on lean, premixed, partially vaporized fuel-air mixtures quality and nitrogen oxides emissions

An analysis was conducted of the effect of flameholding devices on the precombustion fuel-air characteristics and on oxides of nitrogen (NOx) emissions for combustion of premixed partially vaporized mixtures. The analysis includes the interrelationships of flameholder droplet collection efficiency, reatomization efficiency and blockage, and the initial droplet size distribution and accounts for the contribution of droplet combustion in partially vaporized mixtures to NOx emissions. Application of the analytical procedures is illustrated and parametric predictions of NOx emissions are presented.

Cooper, L. P.↗

NASA NTRS1980

Supercritical fuel injection system

a fuel injection system for gas turbines is described including a pair of high pressure pumps. The pumps provide fuel and a carrier fluid such as air at pressures above the critical pressure of the fuel. A supercritical mixing chamber mixes the fuel and carrier fluid and the mixture is sprayed into a combustion chamber. The use of fuel and a carrier fluid at supercritical pressures promotes rapid mixing of the fuel in the combustion chamber so as to reduce the formation of pollutants and promote cleaner burning.

Marek, C. J.↗

NASA NTRS1980

Effect of degree of fuel vaporization upon emissions for a premixed partially vaporized combustion system

An experimental and analytical study of the combustion of partially vaporized fuel-air mixtures was performed to assess the impact of the degree of fuel vaporization upon emissions for a premixing-prevaporizing flametube combustor. Data collected in this study showed near linear increases in nitric oxide emissions with decreasing vaporization at equivalence ratios of 0.6. For equivalence ratios of 0.72, the degree of vaporization had very little impact on nitric oxide emissions. A simple mechanism which accounts for the combustion of liquid droplets in partially vaporized mixtures was found to agree with the measured results with fair accuracy with respect to both trends and magnitudes.

Cooper, L. P.↗

NASA NTRS1979

Effect of degree of fuel vaporization upon emissions for a premixed prevaporized combustion system

An experimental and analytical study of the combustion of partially vaporized fuel/air mixtures was performed to assess the impact of the degree of fuel vaporization upon emissions for a premixing-prevaporizing flametube combustor. Data collected showed near-linear increases in NOx emmissions with decreasing vaporization at equivalence ratios of 0.6. For equivalence ratios of 0.72, the degree of vaporization had very little impact on NOx emissions. A simple mechanism which accounts for the combustion of liquid droplets in partially vaporized mixtures was found to agree with the measured results with fair accuracy with respect to both trends and magnitudes.

Cooper, L. P.↗

NASA NTRS1979

Effect of degree of fuel vaporization upon emissions for a premixed prevaporized combustion system

An experimental and analytical study of the combustion of partially vaporized fuelair mixtures was performed to assess the impact of the degree of fuel vaporization upon emissions for a premixing-prevaporizing flametube combustor. Data collected show near linear increases in nitrogen oxide emissions with decreasing vaporization at equivalence ratios of 0.6. For equivalence ratio of 0.72, the degree of vaporization had very little impact on nitrogen oxide emissions. A simple mechanism which accounts for the combustion of liquid droplets in partially vaporized mixtures was found to agree with the measured results with fair accuracy with respect to both trends and magnitudes.

Cooper, L. P.↗

NASA NTRS1979

Effect of degree of fuel vaporization on emissions for a premixed-prevaporized combustor system

The impact of the degree of fuel vaporization upon emission from a flametube combustor was studied using an inlet air pressure of 3 x 10 to the 5th power pascals, inlet air temperatures of 600K and 700K, a reference velocity of 35 meters per second and equivalence ratios of .6 and .72 using Jet A fuel. Incoming air was preheated to temperatures from 600K to 700K by a nonvitiating preheater. Jet A fuel was injected into this airstream through two different fuel injectors manifolded together and mounted in series upstream of a watercooled preforated plate flameholder. The fuel-air mixture burned in a watercooled combustor section. Samples of the fuel-air mixture upstream of the flameholder were obtained for analysis to determine the local degree of fuel vaporization and the fuel-air ratio. Samples of the combustion products were analyzed to determine gaseous emissions. The effects of vaporization on carbon monoxide and nitric on carbon monoxide and nitric oxide emissions are presented.

Cooper, L. P.↗

NASA NTRS1977

An experimental study of reactive turbulent mixing

An experimental study of two coaxial gas streams, which react very rapidly, was performed to investigate the mixing characteristics of turbulent flow fields. The center stream consisted of a CO-N2 mixture and the outer annular stream consisted of air vitiated by H2 combustion. The streams were at equal velocity (50 m/sec) and temperature (1280 K). Turbulence measurements were obtained using hot film anemometry. A sampling probe was used to obtain time averaged gas compositions. Six different turbulence generators were placed in the annular passage to alter the flow field mixing characteristics. The turbulence generators affected the bulk mixing of the streams and the extent of CO conversion to different degrees. The effects can be related to the average eddy size (integral scale) and the bulk mixing. Higher extents of conversion of CO to CO2 were found be increasing the bulk mixing and decreasing the average eddy size.

Cooper, L. P.↗

NASA NTRS1977

An experimental study of reactive turbulent mixing

An experimental study of the turbulent mixing of two coaxial gas streams, which react very rapidly (pseudo-hypergolic chemical kinetics), was performed to investigate the mixing characteristics of turbulent flow fields. The center stream consisted of a CO-N2 mixture and the outer annular stream consisted of air vitiated by H2 combustion. The streams were at equal velocity (50 m/sec) and temperature (1280 K). Turbulence measurements were obtained using hot film anemometry. A sampling probe was used to obtain time averaged gas compositions. Six different turbulence generators were placed in the annular passage to alter the flow field mixing characteristics. The turbulence generators affected the bulk mixing of the streams and the extent of CO conversion to different degrees. The effects can be related to the average eddy size and the bulk mixing. Higher extents of conversion of CO to CO2 were found by increasing the bulk mixing and decreasing the average eddy size.

Cooper, L. P.↗

NASA NTRS1975

A study of reactive turbulent mixing

This paper describes the development of a probe to study turbulent reactive mixing of two hypergolic streams of gas. The streams contain CO and O2 respectively and are mixed at 1400 K. The probe is a water cooled sonic orifice probe followed by a Fanno duct. Tests showed that it rapidly quenched the reaction, and that time-average, ingested gas composition accurately reflected the time-average composition at the sampling point. A new way to measure mixedness to the molecular level in a reactive flow situation is described, based on time-average compositions at the probe. This definition is compared to the definition of intensity of segregation which can be used for unreactive mixing situations. Finally, the probe is used to examine centerline composition in a confined coaxial mixing situation.

Roler, M. A.↗