Highly resolved numerical simulation of combustion downstream of a rocket engine igniter

Buttay, Romain; Gomet, Laurent; Lehnasch, Guillaume; Mura, Arnaud

doi:10.1007/s00193-017-0715-y

Cited by 15 publications

(5 citation statements)

References 37 publications

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“…From a more general point of view, a normalized premixedness index can also be directly deduced from the following expression [23]:…”

Section: Existing Definitions Of the Flame Indexmentioning

confidence: 99%

“…(4) or Eq. (5), remain still very popular today [23][24][25][26]. However, previous analyses from Fiorina et al [8] and Knudsen and Pitsch [16] put some of their limitations into evidence.…”

Section: Existing Definitions Of the Flame Indexmentioning

confidence: 99%

“…Aside from the intrinsic shortcomings of any blending procedures, it seems worth emphasizing that the proposal of an improved flame index for the the analysis of partially premixed conditions remains a very relevant and challenging issue for combustion theory and modelling. In fact, from a fundamental viewpoint, proceeding with the analysis of partially premixed combustion still remains a quite difficult task and, in this respect, it is noteworthy that, whatever experimental or computational data are considered, one of the starting point of such analyses generally consists in discriminating premixed from non-premixed regions [23,[31][32][33][34]. Despite its limitations, such combustion modes analyses remain often based on the use of the Takeno index [23,[31][32][33].…”

Section: A Proposal For a New Flame Indexmentioning

confidence: 99%

“…In fact, from a fundamental viewpoint, proceeding with the analysis of partially premixed combustion still remains a quite difficult task and, in this respect, it is noteworthy that, whatever experimental or computational data are considered, one of the starting point of such analyses generally consists in discriminating premixed from non-premixed regions [23,[31][32][33][34]. Despite its limitations, such combustion modes analyses remain often based on the use of the Takeno index [23,[31][32][33]. The modified premixedness index that is proposed herein may provide an improved framework to conduct such analyses while keeping one of the most attractive features of the Takeno index compared to other strategies, namely its simplicity.…”

Section: A Proposal For a New Flame Indexmentioning

confidence: 99%

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An extended flame index partitioning for partially premixed combustion

Illana

Mira

Mura

2020

Combustion Theory and Modelling

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Compared to partially premixed combustion (or combustion of non-homogeneous reactants in general), fully premixed and diffusion flames represent only two asymptotic limits of combustion modes. However, the deep knowledge accumulated over the years on these two elementary and archetypal flame prototypes is such that they remain the cornerstone and reference building blocks of most combustion modelling proposals. Therefore, from a general point of view, being able to distinguish between premixed and non-premixed modes of combustion thanks to a flame index appears as a quite appealing but challenging task that still concentrates many research efforts. Indeed, the availability of such an index is not only appealing to proceed with the analysis of either experimental or computational data issued from DNS (or highly resolved LES) databases. It is also an essential ingredient to elaborate advanced flamelet-based multiregime combustion models on the basis of single regime tabulated flamelet databases. In the present study, a new definition of the premixedness index ζ PF is proposed for partially premixed combustion. It is based on a weighted form of the cross-scalar dissipation rate of the mixture fraction Y ξ and progress variable Y c , i.e., quantities that have been previously identified as relevant parameters to describe partially premixed combustion regimes. The relevance of the corresponding index is assessed through a detailed computational procedure that includes three successive validation subsets: counterflow flames (including premixed, rich partially-premixed, and diffusion flames), (ii) stabilized triple flames for three distinct values of the inlet mixture fraction gradient, and finally (iii) unsteady flame kernel developments in nonhomogeneous mixtures of fresh reactants, which are characterized by various initial levels of the segregation rate between the fuel and oxidizer. The proposed premixedness index ζ PF and its counterpart ζ DF = 1 − ζ PF are used as the weighting coefficients between tabulated premixed flamelets (TPF) and tabulated diffusion flamelets (TDF) data, which have been parameterized as functions of Y ξ and Y c . It is noteworthy that, in contrast to some previous proposals of the literature, the present flame index does not require the consideration of any other quantities in addition to those already used to parameterize the flamelets databases, i.e., Y ξ and Y c . The validation procedure makes use of steady and unsteady processes with a priori and a posteriori analyses. In both cases, the comparisons between the results obtained with the proposed flame partitioning and detailed chemistry (DC) computations lead to a satisfactory level of agreement and, from a general viewpoint, the level of agreement is better than the one obtained with either premixed or diffusion flamelet-based models.

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“…From a more general point of view, a normalized premixedness index can also be directly deduced from the following expression [23]:…”

Section: Existing Definitions Of the Flame Indexmentioning

confidence: 99%

Section: Existing Definitions Of the Flame Indexmentioning

confidence: 99%

Section: A Proposal For a New Flame Indexmentioning

confidence: 99%

Section: A Proposal For a New Flame Indexmentioning

confidence: 99%

See 2 more Smart Citations

An extended flame index partitioning for partially premixed combustion

Illana

Mira

Mura

2020

Combustion Theory and Modelling

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“…The effects related to liquid oxygen injection are highlighted. In a study by Buttay et al, the ignition process of the typical rocket engine igniter in the turbulent reaction flow was analyzed [2]. They study ignition processes in the turbulent reactive flow established downstream of highly under-expanded coflowing jets.…”

Section: Introductionmentioning

confidence: 99%

Influence of Ignition Channel on the Ignition Performance of Ignition Device

Chang

Tang

2018

Mathematical Problems in Engineering

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Based on relative theories of gas dynamics and computational fluid dynamics, the flow field computation software ANSYS Fluent was used to simulate the steady flow field of the solid type ignition device of liquid-propellant rocket engine in two working conditions (condition I: without ignition channel, condition II: with ignition channel). On this basis, the influence of ignition channel on the working characteristics of the solid type ignition device of the liquid-propellant rocket engine was analyzed and experimentally tested. The results showed that when the pressure in the combustion chamber was atmospheric pressure, under condition II, the gas velocity at the throat of the ignition device did not reach the sonic velocity, and the position of sonic velocity moved to the downstream section of the ignition channel. Compared to condition I, the gas velocity and energy at the ignition outlet increased, which would be beneficial for initial ignition, and the gas pressure and temperature at the throat increased as well, indicating that the structural strength at the throat should be evaluated. The gas flow, gas pressure, and gas temperature at the ignition outlet decreased compared to working condition I, yet the changes were small and would have minimal effect on the ignition performance. During the pressure increase process in the combustion chamber, the gas pressure, velocity, temperature, flow, and energy at the ignition outlet experienced a steady stage in both working conditions before coming to an inflection point. The inflection point under condition II is smaller than that under condition I. To improve the ignition reliability, the working pressure of the ignition device should be further increased.

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