Isolated droplet & gravity
- The fuel is burnt either as clusters of droplets or isolated droplet. Coupling of two-phase flow, phase change, turbulence, and combustion in these conditions results in a complex system.
- These processes can be understood better under well-defined and controlled conditions in the laboratory using an isolated droplet. Most of the processes observed in actual spray combustion can be investigated in laboratory. The resulting knowledge and quantitative data are useful for design of liquid fuel based combustors.
- Better control (mainly buoyancy) is achieved when effects of gravity are cancelled out. This is established using microgravity conditions. Such experiments are conducted high above the earth's atmosphere (e.g., in a space shuttle/laboratory) or in simulated microgravity on the earth using a drop tower.
Aviation turbine fuel
- Liquid fuel in the form of spray is injected into oxidizing environment in many combustion systems, including rocket engines, gas turbine engines, diesel engines, etc.
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We will consider Aviation Turbine Fuel (ATF) in the experiments. It is a kerosene based fuel commonly called Jet A1. ATF is a multicomponent fuel and its typical composition (in addition to kerosene which is ~75 %) and other relevant properties are summarized below.
- Aromatics (% v/v): 20
- Napthenes (% v/v): 1.5
- Olefins (% v/v): 5
- Boiling point temperature range: 450-553 K
- Calorific value: 42.8 MJ/kg fuel
