MATHEMATICAL MODELING OF THE METALLIZED SOLID PROPELLANT IGNITION BY A HIGH-TEMPERATURE CONVECTIVE FLOW

This paper presents a mathematical model and a methodology to calculate stationary combustion of a metallized solid propellant with aluminum additives ignited by a hightemperature convective flow. The study considers the ignition of a semi-infinite slab of the metallized solid propellant which is blown over by an unlimited high-temperature flow. A boundary-layer approximation is used to develop the ignition model. The high-temperature blowing effect is taken into account in the model by means of turbulent heat and mass transfer. The paper provides a numerical and theoretical analysis on the impact of the velocity and temperature of the convective flow on the ignition time delay and the stationary combustion mode establishment. The analysis shows that the proposed approach allows calculating the time of the ignition delay and stationary combustion mode establishment for the metallized solid propellant. Moreover the ignition delay and the period of the stationary combustion mode establishment are found to be controlled by both the velocity and temperature of the convective flow.

Experimental and Numerical Analysis of an Ignition Sequence in a Multiple-Injectors Burner

The design of a gas turbine combustion chamber integrates multiple contradicting objectives. Among all the parameters available to the engineers, the number of fuel injection systems and their spacing are crucial information which need to be fixed early on in the design phase. Indeed, such choices not only impact the cost and size of the combustor but they also affect the operability of the future engine. One key objective behind these parameters is the ignition time delay needed for the whole combustion chamber to successfully light. To gather knowledge in the ignition process that takes place in real gas turbine engines, current research orient towards the development of experimental facilities that complement high fidelity unsteady numerical simulations. In this context, a multi-injectors experimental set-up located at CORIA (France) is used to validate Large Eddy Simulation (LES) tools developed by CERFACS, IFP-EN and CORIA (France). Preliminary validations against experimental data show that for a given inter-injector distance, LES stationary and ignition transient predictions are very promising and recover the main features found in the experiment. Exit mean and root mean square velocity profiles of the steady flow are in good agreement with measurements obtained for all injectors at multiple axial locations. The simulation of the ignition transient phase well captures global events such as the propagation of the flame front from one injector to its neighbors and the related mechanisms. Improvement is however still needed to recover the proper ignition time of the whole burner.

A Novel Dual-Electrode Plug to Achieve Intensive Electric Field for High Performance Ignition

A thorough analysis of electric field is carried out so as to verify that a novel dual-electrode plug can build intensive electric field and can improve the main drawbacks of feeble electric field and low ignition efficiency of the traditional plug. With intensive electric field, the proposed novel plug can achieve high performance ignition, resulting in fuel saving and exhaust reduction. Gauss law is applied for electric field analysis to show that intensive electric field can be built by the novel plug. Then, according to Faraday law a lower-voltage ignition feature accomplished by the plug is discussed. Compared with traditional plug, the novel dual-electrode plug has the following advantages. (1) Much higher energy density is built between the plug electrodes, lowering ignition voltage requirement. (2) Electromagnetic interference (EMI) problem caused by high ignition voltage is readily resolved. (3) Ignition time delay can be improved. (4) The feature to save fuel consuming is achieved. (5) The exhaust of CO and HC is reduced significantly. Practical measurements are fulfilled to validate the electric field analysis and to demonstrate the features of the proposed dual-electrode plug.

Numerical Simulation of the Flame Stabilization inside an Aeroderivative Combustor to be Operated with Waste Bio-Gas

This paper investigates the methods to stabilize a bio-gas flame inside a combustor. A procedure a modelling by dividing the combustor in 8 identical sections, each sections having 343,000 volume cells have been used. Bio-gas composition has been assumed to be 50% methane, 40% carbon dioxide and all the rest to be assimilated with hydrogen in volumetric participation. Due to the different values of ignition time delay, some gas flames already observed to be unstable can be transformed into stable ones by using by-product supplementary fuels