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

2014 ◽  
Vol 71 (2) ◽  
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.

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

2016 ◽  
Vol 139 (1) ◽  
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.

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

2019 ◽  
Vol 47 (2) ◽  
pp. 1487-1491 ◽  
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

Visualization and Analysis of the Multiphase Flow in an Electromagnetically Driven Dosing Pump

2013 ◽  
Author(s):  
Martin Petzold ◽  
Jürgen Weber ◽  
Etienne Dautry ◽  
Olaf Ohligschläger ◽  
Axel Müller
Keyword(s):  
Fluid Flow ◽  
Multiphase Flow ◽  
Experimental Work ◽  
High Speed ◽  
Flow Behavior ◽  
Motor Vehicles ◽  
Critical Flow ◽  
High Speed Camera ◽  
Insight Into ◽  
Dissolved Air

Fluids with a high proportion of dissolved air lead to an increased air release in hydraulic components. Looking at the fluid flow in a piston pump, the resulting multiphase flow may affect its metering performance. To improve effects caused by cavitation, it is necessary to detect and analyze all critical flow areas in detail. This paper presents investigations of the multiphase flow in an electromagnetically driven dosing pump. This type of pump is suitable for metering any kind of liquid in motor vehicles in a very precise manner. Using high speed camera equipment and transparent components for the displacement chamber, the presented experimental work gives a comprehensive insight into the most relevant cavitation effects in the pump. In addition, the pressure inside the displacement chamber is measured with the help of a miniature pressure sensor. By combination of measuring data and visual recordings, cavitation phenomena can be determined precisely, so that a profound understanding of the flow behavior in the pump is achieved.

Analysis of the Flame Structure in a Trapped Vortex Combustor Using Low and High-Speed OH-PLIF

2014 ◽  
Author(s):  
Pradip Xavier ◽  
Alexis Vandel ◽  
Gilles Godard ◽  
Bruno Renou ◽  
Frederic Grisch ◽  
...  
Keyword(s):  
High Speed ◽  
Laser Diagnostics ◽  
Flame Structure ◽  
Combustion Process ◽  
Operating Conditions ◽  
Pollutant Emissions ◽  
Time Resolved ◽  
Lean Combustion ◽  
Stage Combustion ◽  
Trapped Vortex

Operating with lean combustion has led to more efficient “Low-NOx” burners but has also brought several technological issues. The burner design geometry is among the most important element as it controls, in a general way, the whole combustion process, the pollutant emissions and the flame stability. Investigation of new geometry concepts associating lean combustion is still under development, and new solutions have to meet the future pollutant regulations. This paper reports the experimental investigation of an innovative staged lean premixed burner. The retained annular geometry follows the Trapped Vortex Combustor concept (TVC) which operates with a two stage combustion chamber: a main lean flame (1) is stabilized by passing past a vortex shape rich-pilot flame (2) located within a cavity. This concept, presented in GT2012-68451 and GT2013-94704, seems to be promising but exhibits combustion instabilities in certain cases, then leading to undesirable level of pollutant emissions and could possibly conduct to serious material damages. No precise information have been reported in the literature about the chain of reasons leading to such an operation. The aim of this paper is to have insights about the main parameters controlling the combustion in this geometry. The flame structure dynamics is examined and compared for two specific operating conditions, producing an acoustically self-excited and a stable burner. Low and high-speed OH-PLIF laser diagnostics (up to 10 kHz) are used to have access to the flame curvature and to time-resolved events. Results show that the cavity jets location can lead to flow-field oscillations and a non-constant flame’s heat release. The associated flame structure, naturally influenced by turbulence is also affected by hot gases thermal expansion. Achieving a good and rapid mixing at the interface between the cavity and the main channel leads to a stable flame.

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

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.

scholarly journals Process of Multiple Channel Gliding Arc Assisted Combustion Near Lean Blow-out Limit

2021 ◽  
Vol 233 ◽  
pp. 01027
Author(s):  
Weizhen Wang ◽  
Min Jia ◽  
Wei Cui ◽  
Zhibo Zhang
Keyword(s):  
High Speed ◽  
Flame Structure ◽  
Combustion Process ◽  
Plasma Actuators ◽  
Swirl Combustor ◽  
Flow Rates ◽  
Gliding Arc ◽  
Multiple Channel ◽  
Fuel Flow ◽  
Instantaneous Voltage

Multichannel gliding arcs actuators were designed to enhance the non-premixed combustion of the kerosene (RP-3) and air mixture in a swirl combustor near lean blow-out limit. The instantaneous voltage and current of the multichannel gliding arcs and the 1kHz high-speed CH* chemiluminescence imaging of the combustion process were simultaneously measured to show the characteristics of the process assisted by the plasma. When reaching near lean blow-out limit in a flow rate of 225 SLPM, at the combustor inlet, the emission intensity and projected flame assisted by the multichannel gliding arcs remain the same with decreased fuel flow rates from 3 to 1 ml/min, which assisted by the single gliding arc decreases nevertheless. The flame structure under the influence of plasma actuators with various channel numbers evolves differently owing to the differences in plasma distributions.

Simulation of the Ignition Process in an Annular Multiple-Injector Combustor and Comparison With Experiments

2014 ◽  
Vol 137 (3) ◽  
Author(s):  
Maxime Philip ◽  
Matthieu Boileau ◽  
Ronan Vicquelin ◽  
Thomas Schmitt ◽  
Daniel Durox ◽  
...  
Keyword(s):  
High Speed ◽  
Burning Velocity ◽  
Flame Structure ◽  
Combustion Model ◽  
Ignition Process ◽  
High Speed Imaging ◽  
Flamelet Model ◽  
Swirl Injectors ◽  
Eddy Simulation ◽  
Annular Combustor

Ignition is a problem of fundamental interest with critical practical implications. While there are many studies of ignition of single injector configurations, the transient ignition of a full annular combustor has not been extensively investigated, mainly because of the added geometrical complexity. The present investigation combines simulations and experiments on a complete annular combustor. The setup, developed at EMC2 (Energétique Moléculaire et Macroscopique Combustion) Laboratory (Mesa, AZ), features sixteen swirl injectors and quartz walls allowing direct visualization of the flame. High speed imaging is used to record the space time flame structure and study the dynamics of the light-round process. On the numerical side, massively parallel computations are carried out in the large eddy simulation (LES) framework using the filtered tabulated (F-TACLES) flamelet model. Comparisons are carried out at different instants during the light-round process between experimental data and results of calculations. It is found that the simulation results are in remarkable agreement with experiments provided that the thermal effects at the walls are considered. Further analysis indicate that the flame burning velocity and flame front geometry are close to those found in the experiment. This investigation confirms that the LES framework used for these calculations and the selected combustion model are adequate for such calculations but that further work is needed to show that ignition prediction can be used reliably over a range of operating parameters.

scholarly journals Polarity symmetry of leaders in moist air

2021 ◽  
Author(s):  
Shengxin Huang ◽  
Weijiang Chen ◽  
Zhong Fu ◽  
Weidong Shi ◽  
Nianwen Xiang ◽  
...  
Keyword(s):  
Temporal Resolution ◽  
High Speed ◽  
High Speed Camera ◽  
Moist Air ◽  
Macroscopic Behavior ◽  
Outstanding Problem ◽  
The Difference ◽  
Insight Into ◽  
Bidirectional Development

Abstract The most important physics underlying lightning is the leader discharge. The presence or absence of space stems/leaders in leader steps is the key to the polarity asymmetry of leaders, which describes the difference in macroscopic behavior between positive and negative leaders and is a long-term consensus among lightning physicists. It is generally believed that negative leader steps are led by space stem, and there is no space stem/leader in positive leader discharges. Here we report the emergence of the space stem and the bidirectional development of the space leader in positive leader steps in moist air, using a high-speed camera with unprecedented spatial-temporal resolution. The lifetime of space stem/leader in positive leader steps is shorter than that in negative leader steps, causing the uncover of space stem/leader in previous studies. The bidirectional development of space leaders in positive leader steps may be an important source for VHF radiations, illuminating insight into the outstanding problem that how positive lightning leaders produce VHF radiation.

scholarly journals Large Eddy Simulation of Light-Round in an Annular Combustor With Liquid Spray Injection and Comparison With Experiments

2017 ◽  
Vol 140 (2) ◽  
Author(s):  
Théa Lancien ◽  
Kevin Prieur ◽  
Daniel Durox ◽  
Sébastien Candel ◽  
Ronan Vicquelin
Keyword(s):  
Large Eddy Simulation ◽  
High Speed ◽  
Flame Structure ◽  
Ignition Process ◽  
Two Phase ◽  
Eddy Simulation ◽  
Large Eddy ◽  
Annular Combustor ◽  
Intensified Charge Coupled Device ◽  
Aero Engines

The light-round is defined as the process by which the flame initiated by an ignition spark propagates from burner to burner in an annular combustor, eventually leading to a stable combustion. Combining experiments and numerical simulation, it was recently demonstrated that under perfectly premixed conditions, this process could be suitably described by large eddy simulation (LES) using massively parallel computations. The present investigation aims at developing light-round simulations in a configuration that is closer to that found in aero-engines by considering liquid n-heptane injection. The LES of the ignition sequence of a laboratory scale annular combustion chamber comprising sixteen swirled spray injectors is carried out with a monodisperse Eulerian approach for the description of the liquid phase. The objective is to assess this modeling approach of the two-phase reactive flow during the ignition process. The simulation results are compared in terms of flame structure and light-round duration to the corresponding experimental images of the flame front recorded by a high-speed intensified charge-coupled device camera and to the corresponding experimental delays. The dynamics of the flow is also analyzed to identify and characterize mechanisms controlling flame propagation during the light-round process.

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