Influence of Main Swirler Vane Angle on the Ignition Performance of TeLESS-II Combustor

In order to balance the low emission and wide stabilization for lean premixed prevaporized combustion, the centrally staged layout is preferred in advanced aero-engine combustors. However, compared with the conventional combustor, it is more difficult for the centrally staged combustor to light up as the main stage air layer will prevent the pilot fuel droplets arriving at igniter tip. The goal of the present paper is to study the effect of the main stage air on the ignition of the centrally staged combustor. Two cases of the main swirler vane angle of the TeLESS-II combustor, 20° and 30° are researched. The ignition results at room inlet temperature and pressure show that the ignition performance of the 30° vane angle case is better than that of the 20° vane angle case. High speed camera, PLIF and CFD are used to better understand the ignition results. The high-speed camera has recorded the ignition process, indicated that an initial kernel forms just adjacent the liner wall after the igniter is turned on, the kernel propagates along the radial direction to the combustor center and begins to grow into a big flame, and then it spreads to the exit of the pilot stage, and eventually stabilizes the flame. CFD of the cold flow field coupled with spray field is conducted. A verification of the CFD method has been applied with PLIF measurement, and the simulation results can qualitatively represent the experimental data in terms of fuel distribution. The CFD results show that the radial dimensions of the primary recirculation zone of the two cases are very similar, and the dominant cause of the different ignition results is the vapor distribution of the fuel. The concentration of kerosene vapor of the 30° vane angle case is much larger than that of the 20° vane angle case close to the igniter tip and along the propagation route of the kernel, therefore, the 30° vane angle case has a better ignition performance. For the consideration of the ignition performance, a larger main swirler vane angle of 30° is suggested for the better fuel distribution when designing a centrally staged combustor.

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Influence of Main Swirler Vane Angle on the Ignition Performance of TeLESS-II Combustor

Journal of Engineering for Gas Turbines and Power ◽

10.1115/1.4034154 ◽

2016 ◽

Vol 139 (1) ◽

Cited By ~ 10

Author(s):

Bo Wang ◽

Chi Zhang ◽

Yuzhen Lin ◽

Xin Hui ◽

Jibao Li

Keyword(s):

High Speed ◽

Inlet Temperature ◽

Main Stage ◽

Ignition Process ◽

High Speed Camera ◽

Fuel Distribution ◽

Fuel Droplets ◽

Planar Laser ◽

Cfd Method ◽

Vane Angle

In order to balance the low emission and wide stabilization for lean premixed prevaporized (LPP) combustion, the centrally staged layout is preferred in advanced aero-engine combustors. However, compared with the conventional combustor, it is more difficult for the centrally staged combustor to light up as the main stage air layer will prevent the pilot fuel droplets arriving at igniter tip. The goal of the present paper is to study the effect of the main stage air on the ignition of the centrally staged combustor. Two cases of the main swirler vane angle of the TeLESS-II combustor, 20 deg and 30 deg are researched. The ignition results at room inlet temperature and pressure show that the ignition performance of the 30 deg vane angle case is better than that of the 20 deg vane angle case. High-speed camera, planar laser induced fluorescence (PLIF), and computational fluids dynamics (CFD) are used to better understand the ignition results. The high-speed camera has recorded the ignition process, indicated that an initial kernel forms just adjacent the liner wall after the igniter is turned on, the kernel propagates along the radial direction to the combustor center and begins to grow into a big flame, and then it spreads to the exit of the pilot stage, and eventually stabilizes the flame. CFD of the cold flow field coupled with spray field is conducted. A verification of the CFD method has been applied with PLIF measurement, and the simulation results can qualitatively represent the experimental data in terms of fuel distribution. The CFD results show that the radial dimensions of the primary recirculation zone of the two cases are very similar, and the dominant cause of the different ignition results is the vapor distribution of the fuel. The concentration of kerosene vapor of the 30 deg vane angle case is much larger than that of the 20 deg vane angle case close to the igniter tip and along the propagation route of the kernel, therefore, the 30 deg vane angle case has a better ignition performance. For the consideration of the ignition performance, a larger main swirler vane angle of 30 deg is suggested for the better fuel distribution when designing a centrally staged combustor.

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Interactive Effects in Two-Droplets Combustion of RP-3 Kerosene under Sub-Atmospheric Pressure

Processes ◽

10.3390/pr9071229 ◽

2021 ◽

Vol 9 (7) ◽

pp. 1229

Author(s):

Hongtao Zhang ◽

Zhihua Wang ◽

Yong He ◽

Jie Huang ◽

Kefa Cen

Keyword(s):

Burning Rate ◽

Atmospheric Pressure ◽

High Speed ◽

Ambient Pressure ◽

Interactive Effects ◽

Propagation Time ◽

High Speed Camera ◽

Single Droplet ◽

Fuel Droplets ◽

Spacing Distance

To improve our understanding of the interactive effects in combustion of binary multicomponent fuel droplets at sub-atmospheric pressure, combustion experiments were conducted on two fibre-supported RP-3 kerosene droplets at pressures from 0.2 to 1.0 bar. The burning life of the interactive droplets was recorded by a high-speed camera and a mirrorless camera. The results showed that the flame propagation time from burning droplet to unburned droplet was proportional to the normalised spacing distance between droplets and the ambient pressure. Meanwhile, the maximum normalised spacing distance from which the left droplet can be ignited has been investigated under different ambient pressure. The burning rate was evaluated and found to have the same trend as the single droplet combustion, which decreased with the reduction in the pressure. For every experiment, the interactive coefficient was less than one owing to the oxygen competition, except for the experiment at L/D0 = 2.5 and P = 1.0 bar. During the interactive combustion, puffing and microexplosion were found to have a significant impact on secondary atomization, ignition and extinction.

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High-Speed Camera Imaging of the Ignition Process in a Heaterless Hollow Cathode

IEEE Transactions on Plasma Science ◽

10.1109/tps.2018.2885380 ◽

2019 ◽

Vol 47 (2) ◽

pp. 1487-1491 ◽

Cited By ~ 2

Author(s):

Hai-Guang Zhang ◽

Zhong-Xi Ning ◽

Yong-Jie Ding ◽

Xi-Ming Zhu ◽

Bin-Hao Jiang ◽

...

Keyword(s):

Hollow Cathode ◽

High Speed ◽

Ignition Process ◽

High Speed Camera ◽

Camera Imaging

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Observation on Solid Propellant Ignition Using High Speed Camera: The Effect of Hot Wire Position on the Combustion Flame Contour

Jurnal Teknologi ◽

10.11113/jt.v71.3718 ◽

2014 ◽

Vol 71 (2) ◽

Cited By ~ 1

Author(s):

Wan Khairuddin Wan Ali ◽

Ang Kiang Long ◽

Mohammad Nazri Mohd. Jaafar

Keyword(s):

Solid Propellant ◽

High Speed ◽

Flame Structure ◽

Combustion Process ◽

Ignition Process ◽

High Speed Camera ◽

Hot Wire ◽

Composite Propellant ◽

Burning Behavior ◽

Insight Into

This paper reports on the discovery of unique flame structure of a composite propellant sample under hot wire ignition. The entire combustion process at atmospheric pressure condition was recorded using a high speed camera. Three hot wire orientations were chosen in this experiment for examining their effects on the propellant burning behavior. The results show that the wire orientations are crucial in propellant combustion process, as different flame patterns were observed when the hot wire orientation was altered. This paper provides an important insight into this specific ignition process that can be useful for researchers in the aerospace industry for better design and more realistic simulation results in ignition control.

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Influence of Main Stage Air Splits on the Ignition Performance of TeLESS-II Combustor

Volume 4A: Combustion, Fuels and Emissions ◽

10.1115/gt2017-63216 ◽

2017 ◽

Author(s):

Xiaotong Mi ◽

Chi Zhang ◽

Bo Wang ◽

Yuzhen Lin

Keyword(s):

Flow Field ◽

Air Flow ◽

Pollutant Emissions ◽

Recirculation Region ◽

Stable Operation ◽

Inlet Temperature ◽

Main Stage ◽

Fuel Distribution ◽

Baseline Case ◽

The Impact

The centrally staged layout is preferred in the advanced aero-engine combustor to achieve low pollutant emissions as well as stable operation in lean premixed prevaporized combustion. However, because the high-speed main stage airflow prevents the pilot fuel droplets arriving at igniter tip and has a strong convection effect on the initial flame kernel, the application of centrally staged combustor is restricted by its poor ignition and lean blow-out performance. In the centrally staged combustor, the main stage and pilot stage have strong coupled influences on the flow field and fuel distribution. The aim of this paper is to research the impact of the main stage air split on the ignition performance for the baseline case and the comparison case of the main swirler in the TeLESS-II combustor. The main stage air flow rate of the comparison case is about 8 percent less than that of the baseline case. The results of the ignition test at room inlet temperature and pressure indicate that the ignition performance of the comparison case is significantly better than that of the baseline case. The results of the lean blow-out tests show that the main stage air splits do not make the lean blow-out performance worse. To achieve a better understanding of the test results, PLIF technology and CFD analysis were used to measure the fuel distribution and non-reacting flow field. The PLIF and CFD results demonstrate that the most of the fuel spray disperse outward into the main stage cold airflow in the baseline case so that the pilot flame is hard to be established, which leads to poor ignition performance. On the other hand, in the comparison case, the most of the fuel is confined in the recirculation region, which gives a better ignition performance. Compared with the baseline case, the main stage airflow velocity decays faster in the comparison case. It changes the direction of the instantaneous velocity in the spark vicinity, which makes it more likely for the ignition kernel to be captured by the recirculation stream in the comparison case. Therefore, the different fuel distribution and flow field characteristics cause the ignition performance improvement in the comparison case. The improvement is due to the different main stage air flow rates, which is the consequence of the main stage air split.

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Experimental Investigation of Dual-Swirl Spray Flame in a Fuel Staged Optical Model Combustor With Laser Diagnostics

10.1115/gt2021-58706 ◽

2021 ◽

Author(s):

Siheng Yang ◽

Jianchen Wang ◽

Zhichao Wang ◽

Meng Han ◽

Yuzhen Lin ◽

...

Keyword(s):

Heat Release ◽

Shear Layer ◽

Optical Model ◽

Flame Structure ◽

Operating Conditions ◽

Inlet Temperature ◽

Main Stage ◽

Staged Combustion ◽

Swirl Number ◽

Fuel Distribution

Abstract Lean premixed prevaporized combustors often feature staged combustion with a premixed main flame anchored by the nonpremixed pilot flame to obtain a wide operating range. Interaction between pilot flame and main flame is complex. The present article investigates the flame topologies and flame-fuel interactions in separated stratified swirl flames under various operating conditions (fuel to air ratio FAR and fuel stage ratio α) and injector designs (main stage swirl number Sm and fuel injection angle JA). Experiments are carried out in the centrally staged optical model combustor at inlet pressure P3 = 0.49–0.7 MPa and inlet temperature T3 = 539 K. At first, the flame structures obtained from OH-PLIF are investigated and discussed for the baseline injector (Sm = 0.9, JA = −50°). The V-shaped flame is stabilized in the inner shear layer (ISL) with the flame attachment point located at the lip for the pilot flame mode (α = 1). Dual flame is observed in the combustor for the fuel staged combustion (α < 1): the main flame stabilized in the outer shear layer (OSL) and the pilot flame stabilized in the inner shear layer (ISL). For increasing α from 0.15 to 0.25, gaps between the main flame and pilot flame are decreased, indicating a stronger interaction between the two flames. The flame structure for different injector geometries is then investigated. It is found that the higher main stage swirl number induces a larger flame opening angle, decreasing the interaction between two flames. Fuel injected into crossflow (JA = −50°) is found to generated a more separated flame, decreasing the flame interactions. Finally, fuel distribution measured by kerosene-PLIF is analyzed with the correlation to flame structure. Results show that the existence of a good mixing of fuel and fresh air in ISL and OSL provide favorable conditions for chemical reaction with high heat release. The OH distribution is highly correlated to fuel distribution. The fuel zone is located at the inner side of high OH region, indicating the reaction and heat release take place after the mixing of preheating of fuel-air mixture.

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Effect of Swirl Cup’s Venturi Shape on Spray Structure and Ignition Process

Volume 4A: Combustion, Fuels and Emissions ◽

10.1115/gt2014-25216 ◽

2014 ◽

Cited By ~ 4

Author(s):

Xiaofeng Wang ◽

Yuzhen Lin ◽

Haosheng Hu ◽

Chi Zhang ◽

Yao Kang

Keyword(s):

Spatial Distribution ◽

High Speed ◽

Side Wall ◽

Video Camera ◽

Spark Ignition ◽

Ignition Process ◽

Turbine Engine ◽

Fuel Droplets ◽

Spray Structure ◽

Air Stream

In a gas turbine engine combustor, combustion performance is tied to the spatial distribution of the fuel injected into the dome. Swirl cup, as an air blast atomizer, is widely used to provide a uniform presentation of fuel droplets to the combustor dome. In this paper, two swirl cups with different venturi angle have been studied: case 1 (with narrow venturi angle) and case 2 (with wide venturi angle). Kerosene is injected to the test domain through a simplex nozzle. The spatial distribution of droplet characteristics produced by the two swirl cups were measured using dual-phase Doppler anemometry (PDA). A single cup combustor has been built in order to characterize the swirl cups’ ignition phenomena. Spark ignition test has been performed for ground condition, two swirl cups’ lean ignition limits are obtained, and ignition sequences have been recorded by a high-speed video camera. Comparing the two swirl cups’ small droplets velocity, case 1 swirl cup produces a different velocity profile from typical swirl cup. The air stream outflowing from case 1 swirl cup just ran into the side wall. The droplet size around the spark plug of case 2 is smaller than case 1. Ignition test results show that case 2 swirl cup’s lean ignition limit is wider than case 1’s. Record of the ignition process deepened the understanding of spark ignition of the swirl diffusion flame. It takes some time for the kernel to anchor in swirl cup. The results demonstrate that swirl cup’s venturi shape strongly influence the spray structure. Thereby affect the combustor ignition performance.

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High-speed camera test of newly developed igniter’s charges for artillery rounds

Journal of Physics Conference Series ◽

10.1088/1742-6596/2090/1/012129 ◽

2021 ◽

Vol 2090 (1) ◽

pp. 012129

Author(s):

A Plachá ◽

J Recko

Keyword(s):

High Speed ◽

The Other ◽

Ignition Process ◽

High Speed Camera ◽

Test Results ◽

Black Powder ◽

Time To Ignition ◽

Military Institute ◽

The Military

Abstract The article presents the results of the high-speed camera test of newly developed igniter’s charges for artillery rounds. The test was performed to take a closer look at the ignition process of mixtures, that is, to check the time-to-ignition of samples, and to assess the presence and quantity of solid igniting particles (if any). Five compositions were tested: Three of them contained the new igniter’s charges developed by the Military Institute of Armament Technology, and the other two contained black powder in different granularity classes as a comparison mixture. This article presents the collated test results.

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Flow Field, Spray Distribution and Pilot Flame Stabilization in a Centrally Staged Combustor

Volume 4A: Combustion, Fuels, and Emissions ◽

10.1115/gt2020-14362 ◽

2020 ◽

Author(s):

Bo Wang ◽

Guangming Ren ◽

Xiaohua Gan ◽

Yuzhen Lin

Keyword(s):

Flow Field ◽

High Speed ◽

Stability Boundary ◽

Critical Time ◽

Flame Stabilization ◽

Cycle Duration ◽

High Speed Camera ◽

Double Root ◽

Fuel Distribution ◽

Spray Distribution

Abstract Centrally staged lean premixed prevaporized low emission combustor has achieved great commercial success in the past decade. Pilot flame characteristics is with key importance to centrally staged combustor, which is considered not entirely up to the design of pilot stage, but also influenced by the flow field and fuel distribution of the combustor. The flow field and fuel distribution behaviors in centrally staged combustor are not very clear since the role of LRZ is unknown, as well as the pilot flame stabilization mechanism. The goal of this paper is to study the flow field, spray distribution and pilot flame stabilization in centrally staged combustor. This paper designs a comparison scheme of the dome lip for study. Particle image velocimetry, Planar Mie scattering measurements and high-speed camera experiments are conducted to get an in depth understanding on the flow field, spray distribution characteristics and pilot flame stabilization in a centrally staged combustor. The flow field with a 3.0 mm lip incline is quite different. Two PRZs forms, one connected with the LRZ and the other at the outlet of pilot stage. Pilot flow no longer joins to the main flow but flows alone in the center. It seems like it is the decoupling pilot stage air cutting PRZ into two PRZs. The pilot spray has a conical boundary and it is probably formed by the high velocity main air flow. A considerable number of fuel droplets are involved in LRZ with the lip incline. Two shapes of pilot flame are observed, the V-shaped flame and double root flame. High-speed camera has captured the flame stabilization process close to LBO. As for the V-shaped pilot flame, the central flame root performs an extinction/relight cycle close to LBO. The cycle duration time is much longer than the critical time of swirl cup methane flame previously reported. As for the double root pilot flame, the central flame root is lighted before the lip flame root and it is the central flame that plays the leading role in stabilizing the whole flame. The lip flame root can weaken the quench effect of main air and broaden the flame stability boundary. A relatively large lip height is recommended for the consideration of the LBO performance.

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