Experimental and numerical investigation of high-pressure nitromethane combustion

The burning rate of liquid nitromethane as a function pressure is known to exhibit slope breaks, following Saint-Robert's law only in limited regions pressure. present paper presents experimental and modeling results with the objective better understand this behavior. A new facility used visually observe combustion process from 3 101 MPa allowing for measurement rates tubes various diameters high-speed cinematography. series calculations are performed increasing complexity first studying vapor phase flame propagation ideal gas equation state then real state. These compared previously published predictions regression using same kinetic model Theory indicates that, at high pressures, freely propagating vapor-phase speed should agree rates. Combined, these enable further insight into mechanisms breaks complex Three regimes were identified low-pressure regime exponent 1.16 exists where occurs distinct interface between gas. At approximately 18 MPa, an abrupt increase that associated critical point mixture near-surface species producing exponents ranging 2–10. Above pressure, loss surface tension induces waves large-scale hydrodynamic instabilities. With continue but gradual decrease towards value ∼0.75. highest instabilities disappear, propagates turbulent cellular front, which depends upon tube diameter.