Burn rate (chemistry)

About: Burn rate (chemistry) is a research topic. Over the lifetime, 847 publications have been published within this topic receiving 8908 citations. The topic is also known as: Burning rate.

Limits of Stable Combustion in an Engine of Ultra-Small Spacecrafts

Abstract: Using the analytical and numerical methods, an analysis of low-frequency stability of combustion in a micro-thruster rocket of solid propellant under the condition of a loss of heat from the combustion zone is conducted. The problem of stability of the engine is solved by applying the phenomenological T0*-theory. In a micro-thruster rocket, the domain of stable combustion becomes much narrower, due to occurrence of strong 0-instability, i.e. the exponential grow of perturbations with time. Nevertheless, there is a range of parameters, characterizing the laws of propellant combustion for which the sustained combustion may be possible.

Energy Management in Rocket Propulsion

Abstract: The optimal management of the available energy in an ideal single-stage rocket produces a velocity increment that is larger than the value provided by Tsiolkovsky’ s equation. This result is immediately applicable when a limited amount of energy is available from a source that is external to the propellant. A storage device is instead necessary to delay partially the use of the energy that is produced by the combustion of a reactive working e uid. The penalty of the energy-source mass and the presence of an upper limit on the propellant temperature are also discussed; in the latter case, the addition of a low-molecular-weight, inert propellant to the reactive propellant is benee cial during the e nal phase of the rocket acceleration.

Flammability Limits and the Oscillatory Burning of Solid Propellants at Low Pressure.

Abstract: : A one-dimensional analysis of the small-amplitude oscillatory burning of a solid propellant has been developed. The analysis is based on a simplified flame model using quasi-steady gas-phase approximation. The difference between this analysis and previous analyses is that radiant heat loss from the burning surface has been included in the present theory. This heat loss produces significant qualitative and quantitative differences in the unsteady behaviour of solid propellants at low pressures. The effect of initial temperature on the stability of the combustion process has also been examined. (Modified author abstract)

One-dimensional combustion instability studies with moving boundaries in an end-burning test motor

Abstract: A quasi-steady one-dimensional arbitrary moving boundary code is progressively developed for the objective of solving; full transient, moving boundary, rocket motor internal flow field problem. In this analysis, the propellant surface is modeled as moving, contrary to the common approach that assumes a stationary propellantburning surface. A one-dimensional Godunov type exact Riemann Solver is developed that can handle the boundary conditions for advancing and retarding walls. Moving propellant boundaries are handled with fixed grid approach by clipping the boundary inside grid points. The classical time-dependent inflow/outflow characteristic boundary conditions are implemented for exhaust. The mass injected from the propellant surface is modeled as the mass generated inside the control volume, represented in the source terms of the Euler equations. The resulting code is verified for moving boundary test cases, nozzle type geometries, and small test motors. Finally solid propellant combustion instability prediction capability is searched for an end-burning test motor configuration by comparing different burn rate models. Both steady state burning rate and a transient burning rate law is applied as a boundary condition. Acoustic oscillations at different frequencies are observed during the operation time. The pulsed oscillations occurred in higher modes. Results are discussed for fast and slow regression rates, long motors and steady state pressure levels. Frequency analysis of the flow variables and burning rate variations are done real time during the computations using non-stationary data analysis techniques. Pressure response function of the model propellant is assumed known from experiments available from the literature.

Experimental investigation on combustion characteristic of PE in solid fuel ramjet

Abstract: The combustion characteristics of polyethylene( PE) in the solid fuel ramjet( SFRJ) were investigated by using a direct tube test facility.The impact of air mass flow rate and stepheight ratio on regression rate and performance were considered.Under different experimental conditions,rules for the variation of combustor pressure,after burning chamber pressure and after burning chamber temperature along with time,and the mean regression rate and the local regression rate of PE were obtained. The results show that a pressure difference exists between the chamber and the after burning chamber when the SFRJ works,and the pressure difference is about 0.01 ~ 0.02 MPa; the temperature in the after burning chamber reduces as the air mass flow rate increases; increase of the stepheight ratio helps to raise the temperature in the after burning chamber; the mean regression rate of the fuel increases as the stepheight ratio and the air mass flow rate increase,and the mean regression rate of the fuel is in a linear function relationship with the stepheight ratio and in a power function relationship with the air mass flow rate.