Combustion Characteristics of a Supersonic Combustor with a Large Cavity Length-to-Depth Ratio

Li, Xiang; Lei, Qingchun; Zhao, Xiaocun; Fan, Wei; Chen, Shuang; Chen, Li; Tian, Ye; Zhou, Quan

doi:10.3390/aerospace9040214

Cited by 6 publications

(2 citation statements)

References 40 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In order to distinguish from the combustion mode, the POD mode will be written as PDM (below). Xiang Li [38] summarized the combustion stabilization modes and their oscillation frequency, as reported in the previous literature.…”

Section: Introductionmentioning

confidence: 99%

Supersonic Combustion Mode Analysis of a Cavity Based Scramjet

Meng

Sun

et al. 2022

Aerospace

View full text Add to dashboard Cite

Since flame stability is the key to the performance of scramjets, scramjet combustion mode and instability characteristics were investigated by using the POD method based on a cavity-stabilized scramjet. Experiments were developed on a directly connected scramjet model that had an inlet flow of Mach 2.5 with a cavity stabilizer. CH* chemiluminescence, schlieren, and a wall static pressure sensor were employed to observe flow and combustion behavior. Three typical combustion modes were classified by distinguishing averaged CH* chemiluminescence images of three ethylene fuel jet equivalence ratios. The formation reason was explained using schlieren images and pressure characteristics. POD modes (PDMs) were determined using the proper orthogonal decomposition (POD) of sequential flame CH* chemiluminescence images. The PSD (power spectral density) of the PDM spectra showed large peaks in a frequency range of 100–600 Hz for three typical stabilized combustion modes. The results provide oscillation characteristics of three scramjet combustion modes.

show abstract

Section: Introductionmentioning

confidence: 99%

Supersonic Combustion Mode Analysis of a Cavity Based Scramjet

Meng

Sun

et al. 2022

Aerospace

View full text Add to dashboard Cite

show abstract

“…The complex flow field environment in scramjet combustors brings great challenges to flame stabilization and efficient combustion, so flame stabilization in the supersonic combustor usually requires the help of various flame stabilizers, such as transverse injection [1], backward steps, slopes, struts, and cavities [2][3][4][5][6], etc. For the case where the fuel transverse injection works alone, it is difficult to stabilize the flame in the supersonic flow [7][8][9] unless the total enthalpy of the incoming flow reaches the self-ignition condition of the fuel.…”

Section: Introductionmentioning

confidence: 99%

Effect of Fuel-Injection Distance and Cavity Rear-Wall Height on the Flameholding Characteristics in a Mach 2.52 Supersonic Flow

Wang

et al. 2022

Aerospace

View full text Add to dashboard Cite

The ethylene-fueled flameholding characteristics of a cavity-based scramjet combustor are experimentally and numerically investigated. The test facility used the air heater, which heats air from room temperature to total temperature 1477 K. A nozzle is installed behind the heater outlet to increase the air speed to Mach 2.52. Two cavity geometries with different rear-wall heights of 8 mm and 10 mm and two injection distances upstream of the cavities of 10 mm and 40 mm are compared to show the effect of these parameters. The CH* spontaneous emission images obtained by dual-camera synchronous shooting and the wall-pressure distribution obtained by a pressure-scan system are used to capture the flame dynamics. The global equivalence ratio range for different combination schemes is controlled from 0.14 to 0.27 in this paper. The results show that the conventional cavity (the rear-wall height is 10 mm) and the shorter injection distance can effectively decrease the lean blowoff limit of the combustor, while the rear-wall-expansion cavity (the rear-wall height is 8 mm) and the longer injection distance can effectively increase the rich blowoff limit. Compared with the injection distance, the rear-wall height of the cavity has little effect on the oscillation distribution of the shear layer-stabilized flame. However, the fuel-injection distance and cavity rear-wall height both have great influence on the spatial distribution of the flame.

show abstract

Mechanisms of ignition and combustion instability in a scramjet combustor with micro-rocket torch using dynamic mode decomposition

Ogawa

2024

Physics of Fluids

View full text Add to dashboard Cite

Achieving ignition and stable combustion in scramjet combustors, which have residence times of milliseconds, requires effective flame stabilization. Previous studies have explored stable forced ignition and flame holding using various igniters, such as micro-rocket and plasma jet torches. This study investigated the forced ignition and combustion instability of a scramjet combustor with a micro-rocket torch. Although the micro-rocket torch successfully ignited the combustor in previous experiments, combustion instabilities were observed in the cavity flame holder through OH* chemiluminescence images. To understand the mechanisms behind forced ignition and combustion instability, dynamic mode decomposition (DMD) was employed. DMD is effective for analyzing combustion dynamics because it extracts spatiotemporally coherent structures from high-dimensional data. The OH* chemiluminescence images from prior experiments were analyzed using DMD to identify the dominant modes associated with the combustion instability. Power spectrum density analysis revealed that low-frequency instabilities (100–400 Hz) were caused by fuel injector flame feedback, very low frequencies (15–50 Hz) were due to torch gas injector flame feedback, and high frequencies (over 1000 Hz) resulted from interference between the cavity flame holder and the flow field. These findings provide insights into the complex flow dynamics within the cavity flame holder and shear layer, thereby enhancing the understanding of combustion instability mechanisms in scramjet engines equipped with micro-rocket torches.

show abstract

Combustion Characteristics of a Supersonic Combustor with a Large Cavity Length-to-Depth Ratio

Cited by 6 publications

References 40 publications

Supersonic Combustion Mode Analysis of a Cavity Based Scramjet

Supersonic Combustion Mode Analysis of a Cavity Based Scramjet

Effect of Fuel-Injection Distance and Cavity Rear-Wall Height on the Flameholding Characteristics in a Mach 2.52 Supersonic Flow

Mechanisms of ignition and combustion instability in a scramjet combustor with micro-rocket torch using dynamic mode decomposition

Contact Info

Product

Resources

About