Effects of temperature variation among droplets in an evaporating fuel spray
It is well known that the boiling point of a typical fuel blend is different from those of the pure components. For an ideal mixture of liquids at a given state, the new boiling point can be calculated either theoretically or can be obtained from experimental data (e.g. ASTM distillation curve). The ASTM distillation data for JP-4, for example, show that the boiling point can change by about 250 C depending upon the degree of evaporation. Droplets of different diameters in a spray undergo different degrees of evaporation and hence have different boiling temperatures. The purpose of the present paper is to investigate the effects of temperature distribution in the spray on the local overall fuel-air ratio. Sprays of both JP-8 and JP-4 (ASTM distillation data) are used as examples in a flowing, one-dimensional stream at 20 atm and 680 K. The droplets undergo an initial phase of unsteady heating and finally steady evaporation follows when the wet-bulb temperature is reached. The results of this study show that operating conditions the temperature distribution in a fuel spray can have a significant effect on the local fuel-air mixture and hence on the performance of an air breathing propulsion system. The use of a constant mean boiling temperature rather than the variable boiling temperature will result in significant errors.
- Research Organization:
- University of Southern California, Los Angeles (USA). Dept. of Mechanical Engineering
- OSTI ID:
- 5369386
- Report Number(s):
- AD-P-004559/1/XAB
- Resource Relation:
- Other Information: This article is from JANNAF (Joint Army-Navy-NASA-Air Force) Combustion Meeting (21st) held at Laurel, Maryland on 1-4 October 1984. Volume 1, AD-A150 981, p455-463
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
DROPLETS
BOILING POINTS
EVAPORATION
TEMPERATURE DISTRIBUTION
FUELS
JET ENGINE FUELS
CALCULATION METHODS
COMBUSTION
DISTILLATION
FUEL-AIR RATIO
VARIATIONS
CHEMICAL REACTIONS
OXIDATION
PARTICLES
PHASE TRANSFORMATIONS
PHYSICAL PROPERTIES
SEPARATION PROCESSES
THERMOCHEMICAL PROCESSES
THERMODYNAMIC PROPERTIES
TRANSITION TEMPERATURE
400800* - Combustion
Pyrolysis
& High-Temperature Chemistry