Pyrotechnic Igniter Research Articles

A comparative study between two ignition sources: Electric igniter versus pyrotechnic igniter

The risk assessment of combustible explosive dust is based on the determination of the probability of dust dispersion, the identification of potential ignition sources and the evaluation of explosion severity. It is achieved in most of cases with the two main experimental normalized devices such as the Hartmann tube (spark ignition) and the 20 L spherical bomb (with two 5 kJ pyrotechnic ignitors).Ignition energy of the 5 kJ ignitor is well calibrated and generates a reproducible ignition. But, on the other hand, this ignition is not punctual and the over pressure produced is nearly 2 bar. Moreover, the pyrotechnic igniter accelerates the combustion with multi ignition points in a large volume and that disturbs the flame propagation. In this way, this ignition source does not allow to analyze the combustion products because the composition of the pyrotechnic igniter was found in the combustion products.This paper deals with the comparison of two ignition sources in the 20 L spherical bomb. Different explosive dusts of great industrial interest are studied with electrical and pyrotechnic ignitors, in order to understand, first, the influence of each type of igniter on the explosion behaviour and then to evaluate the possibility of establishing a correspondence between parameters obtained with these two ignition sources.Severity parameters of nicotinic acid, aluminium powder and titanium alloy were measured by using the two types of ignition system in our 20 L spherical bomb equipped with the Kühner dihedral injector. The explosion overpressure P and the rate of pressure rise (dPdt) were measured in a large range of concentration allowing to propose correlations between electrical and pyrotechnic ignition for each parameter and each type of powder. These correlations aim to link the tests used with two different collections of experimental parameters for the same dust. The relevance of these correlations will be discussed.

Study into influence of different types of igniters on the explosion parameters of dispersed nitrocellulose powder

Nitrocellulose is a flammable compound produced by cellulose nitration. The nitrocellulose production and handling are associated with a risk of fire and explosion. Nitrocellulose is used as either collodion cotton (<12.5% N) or as an explosive (>12.5% N). Nitrocellulose is a fibrous or powdered substance and may detonate or burn upon certain conditions. The article compares the combustion parameters of dry nitrocellulose in the KV-150M2-UIBE explosion chamber at the concentrations of 250, 500 and 750 g m−3. To ignite a nitrocellulose sample, six different types of igniters were used. A commercially available 5 kJ pyrotechnic igniter was used as the standard. Also used were a nitrocellulose igniter, a pyrotechnic igniter with magnesium powder and KNO3/KClO3, and an exploding wire (Kanthal and tungsten wire). The examined igniters were found to affect the explosion parameters of dispersed nitrocellulose. The deviation of the explosion constant Kst reached 50% of the standard value. The highest pressure of 12.73 bar g was reached at a concentration of 750 g m−3 and an igniter exploding wire with Kanthal wire. The highest Kst value of 287.9 bar.m.s−1 was achieved at a concentration of 750 g m−3, when using the pyrotechnic igniter with KClO3 and magnesium powder.

Reliability Analysis of Pyrotechnic Igniter for Hydrogen-Oxygen Rocket Engine with Low Temperature Combustion Instability Failure Mode

To evaluate the functional reliability of the pyrotechnic igniter in the failure mode of unstable combustion at low temperature, a reliability and reliability sensitivity analysis method based on the combination of an interior ballistic model and Kriging reliability method is proposed. Through the deterministic interior ballistic simulation, the failure mode of low temperature unstable combustion of the pyrotechnic igniter is examined, while the random variables are introduced to establish the ignition nonlinear implicit function of the pyrotechnic igniter. The ignition display function of the pyrotechnic igniter is established by the Kriging model, which avoids the repeated calculation of true limit state function values. This study provides an efficient approach to evaluate the ignition reliability of the pyrotechnic igniter and compared with the traditional Monte Carlo method to verify the accuracy of the results. Finally, reliability-based sensitivity indices are presented to quantify the significance of random parameters. It is shown that the influence of the uncertainties can be precisely described, and the diameter of the nozzle plays a dominant role in ignition reliability. Additionally, ignition experiments of nozzles with different diameters were performed to verify the result of sensitivity. This can further support the detailed design of the pyrotechnic igniter.

Insight into the Effect of Moisture and Thermal Aging on the Degradation of a Pyrotechnic Igniter Composition through Thermogravimetric Kinetics Coupled with Deconvolution Approach

AbstractIn the present study, the effect of moisture and thermal aging on the degradation of a pyrotechnic igniter composition (PIC) composed of magnesium (Mg) as fuel and dual‐oxidizer of barium nitrate (Ba(NO3)2) and barium peroxide (BaO2) has been investigated to well understand the main compositional and structural changes that may occur. The unaged and aged samples were examined through non‐destructive techniques, namely, Raman and Fourier transform infrared (FTIR) spectroscopies, scanning electron microscopy (SEM), and X‐ray diffraction (XRD). The thermal decomposition behavior and the kinetic parameters of the different Mg‐PIC samples were determined using thermogravimetry (TGA) analysis coupled with a deconvolution approach. The obtained results revealed that the aging processes performed at 65 °C and 85 % relative humidity (RH), respectively, affected the chemical structure of the samples, and the degradation became more pronounced with the increase of the aging time. These changes are attributed to the partial decomposition of barium nitrate, barium peroxide, and the oxidation of magnesium, which generated Ba(NO2)2, MgO, and Mg(OH)2 as degradation products. On the other hand, based on the TGA data, the kinetic modelling was carried out through the deconvolution approach combined with isoconversional kinetic analysis to determine the multiple‐step kinetic behaviors of the different PIC samples. The results revealed that the aging processes may engender various degradation reactions with different activation energies compared to the fresh sample, what can lead to severe changes in stability and untrustworthy performance of the pyrotechnic compositions.

Studies on Effect of Nitrogen Rich Explosives on the Morphology, Thermal and Combustion Behaviour of B/KNO3 Composition

AbstractThe study elucidates the influence of three nitrogen‐rich explosives viz., FOX‐7, FOX‐12, and RS‐RDX on the performance of B/KNO3/PEC igniter composition. The B/KNO3 pyrotechnic igniter compositions with 5, 10 &amp; 15 parts of FOX‐7, FOX‐12, and RS‐RDX were successfully prepared. The compositions were evaluated in terms of surface morphology, heat output, sensitivities, flame temperature, pressure output, ignition delay, time to reach Pmax (BTPmax), and thermal analysis. The closed vessel firing data indicated higher Pmax value and lower BTPmax for FOX‐12 and FOX‐7 based composition. The addition of FOX‐12 and FOX‐7 also reduces the decomposition temperature of B/KNO3 composition without affecting friction and spark sensitivities. The composition having 15 parts RSRDX is the most insensitive to impact among all. Therefore, the addition of insensitive high explosives like RS‐RDX, FOX‐7and FOX‐12 is useful to improve the performance of the igniter composition to achieve low BTPmax and increased pressure output. Optimum performance is exhibited by RS‐RDX‐based compositions.

Influence of the Pyrotechnic Igniter Composition Aging on Explosion Parameters of Dispersed Dusts

A commercially available pyrotechnic igniter was used according to the EN 14034 and ASTM E1226a Standards to study the explosiveness of dispersed dusts. Its pyrotechnic composition consists of 1.2 g of zirconium (40% wt.), barium peroxide (30% wt.) and barium nitrate (30% wt.). The energy released during the combustion of that amount of composition is 5 kJ. The article investigates the influence of aging of the pyrotechnic composition in the igniter on its initiation parameters. In the study, igniters of different years from date of manufacture were used: Igniter 1, manufactured in 2021 (less than 1 year from date of manufacture), and Igniter 2 (more than 2 years from date of manufacture). The study was performed in the KV 150M2 explosion chamber with a volume of 365 L and the 20 L sphere chamber with a volume of 20 L. A standard sample of Lycopodium clavatum was used in the KV 150M2 explosion chamber. Magnesium and benzoic acid were used as the samples in the 20 L sphere explosion chamber. The experiment showed that the explosion pressure Pmax of the igniter with more than 2 years from date of manufacture decreased by up to 10%, while the value of the explosion constant Kst decreased by up to 40%. The attained results proved that aging of igniters affects their explosion parameters and measurement accuracy.

Validation of relations for the determination of pyrotechnic igniter mass

Propellant ignition is an essential process in solid rocket motor operation as it is responsible of starting the combustion and to reliably self-sustain burning of the solid propellant. Despite the importance of igniter design and ignition process, the relations dealing with igniter mass determination are not well studied and not validated against actual motors with a systematic variation of parameters. The main objective of the current research is to validate the available equations in open literature for determination of the mass of igniter pyrotechnic charge. Data from seven real solid propellant rocket motors were used to validate the relations. These motors have different sizes, grain geometries and pyrotechnic compositions. The results show that the equation of Brayan–Lawerene has the smallest root mean square error (RMSE), and so, it is considered more convenient.

Ignition and combustion behavior of zirconium-based pyrotechnic igniters and pyrotechnic delays under aging

Pyrotechnic materials often necessitate high reliability and stability to be utilized in energetic devices. However, prolonged storage of these materials degrades their performance in many ways and results in failure of these devices. Only a few studies have focussed on their burning characteristics, and reported limited understanding on the effect of aging on this behavior of such materials. In this study, ignition and combustion behavior of pyrotechnic materials based on zirconium (Zr) as fuel and potassium perchlorate (KClO4) or iron(III) oxide (Fe2O3) as oxidant are investigated, for various aging conditions. Pristine samples are compared with samples subjected to aging under 91 °C (thermally aged) and seasonal changes (naturally aged). The ignition delay time as a function of maximum wire temperature is obtained through high-speed combustion photography for these samples. Surface features and oxide content are analyzed using scanning electron microscopy and x-ray photoelectron spectroscopy techniques. Results indicate that ignition delay time increases significantly with aging period for both pyrotechnic igniter and pyrotechnic delay samples. However, this time reduces as the maximum wire temperature is increased for all samples. Naturally aged samples exhibit longer ignition delay times and higher metal oxide content when compared to thermally aged ones. Both pre-oxidation of metallic fuel and prior thermal decomposition of oxidizer play an important role in causing this behavior with aged samples.

Investigations on the Modifications in Ignition Delay Time of Shellac-based Pyrotechnic Igniter using Additives of Varying Particle Size

Modifications achieved in the ignition delay time of shellac-based pyrotechnic igniter using different additives of varying particle size are observed and compared. 40 different pyrotechnic compositions were prepared using five additives i.e. aluminium, magnesium, red iron oxide, naphthalene and activated carbon. Four particle sizes i.e. &lt;75 µm, 75-150 µm, 150-300 µm, 300-600 µm and two weight percentages of the additives i.e. 3% and 5% were investigated. A base composition, without any additive, was also prepared to compare and investigate the effects of additives and their particle size on the ignition delay time of the composition. The incorporation of additives significantly reduced the ignition delay time of the base composition. Addition of 5% red iron oxide having a particle size of &lt;75 µm, delivered the maximum decrement in ignition delay time i.e. by 49.7%. Naphthalene of particle size of &lt;75 µm added as 3% in the composition weight, provided the minimum reduction in the ignition delay time i.e. by 13.7%. It was also observed that all of the additives exhibited a similar manner of decrement in ignition delay time as the particle size decreased, except for naphthalene which exhibited an opposite trend.

Towards understanding the effects of heat and humidity on ageing of a NASA standard pyrotechnic igniter

Ageing of pyrotechnic substance, primarily fuel oxidisation, can cause changes in composition that degrade their performance. This study investigates the effect of ageing on zirconium potassium perchlorate (ZPP), a widely used NASA Standard Initiator. Although prior studies have investigated the effects of accelerated ageing on ZPP, this is the first to conduct kinetic analyses at different relative humidity (RH) levels. Here, both thermal and kinetic analyses are conducted for a variety of hygrothermal ageing cases in order to replicate the natural ageing process. X-ray photoelectron spectroscopy (XPS) results reveal that oxidant levels drop and zirconium dioxide levels rise as ZPP ages. Lower heats of reaction and increases in activation energy were also observed under the RH conditions. Calculations using van’t Hoff equation indicate that moisture shortened the lifespan of the unaged ZPP up to about 85% under extreme RH conditions, while significantly deteriorating the heat of reaction, sensitivity, and thus increased the risk of a misfire.

Characterizing pyrotechnic igniter output with high-speed schlieren imaging

Small-scale pyrotechnic igniter output has been characterized using a high-speed schlieren imaging system for observing critical features of the post-combustion flow. The diagnostic, with laser illumination, was successfully applied towards the quantitative characterization of the output from \(\hbox {Ti/KClO}_4\) and \(\hbox {TiH}_{1.65}/\hbox {KClO}_4\) pyrotechnic igniters. The high-speed image sequences showed shock motion, burned gas expansion, and particle motion. A statistical-based analysis methodology for tracking the full-field shock motion enabled straightforward comparisons across the experimental parameters of pyrotechnic material and initial density. This characterization of the mechanical energy of the shock front within the post-combustion environment is a necessary addition to the large body of literature focused on pyrotechnic combustion behavior within the powder bed. Ultimately, understanding the role that the combustion behavior has on the resulting multiphase environment is required for tailored igniter development and comparative performance assessments.

Explosion characteristics tests for micrometer-sized Ag dust cloud with a concentration of 0.8 g/L

A dust explosion is triggered by the rapid combustion of burnable particulate matter suspended in air. Two blank tests and three Ag-dust-cloud explosion tests were performed in a 20-L spherical steel chamber using a 5 kJ pyrotechnic igniter as the energy source in each test. In the explosion tests, no apparent increase in pressure above that found in the blank tests was observed for Ag dust cloud with a concentration of 0.8 g/L. In addition, fine solid particles remaining after the tests showed no evidence of a combustion reaction at the end of the tests. In this research, the thermal decomposition of Ag powders was measured using a differential scanning calorimeter, and the thermal analysis technique to estimate hazards in relation to the samples was employed. The change in enthalpies (H) of the Ag powders were approximately 180, 93, and 53 J/g, and the onset temperatures (T0) were approximately 211.76, 201.41, and 240.46 °C for P3032, P3012, and P3072, respectively. These results support the conclusion that Ag samples with concentrations below 0.8 g/L do not pose a dust explosion hazard.

Shock Tube Effect Inside a Pyrotechnic Igniter

AbstractAn output closure is a critical component of a pyrotechnic igniter. It controls the heat transfer duration of initiation train, stress loading on the propellant grain, and the pressure drop during closure deployment. Normally the pressure profiles calculated by a quasi‐static interior ballistics code are adequate for igniter design evaluation. But following a case of premature closure deployment in which the propellant failed to ignite, the authors discovered that the design geometry mimicked that of a shock tube. The shock tube effect occurred whenever the high‐temperature gases of the initiator were rapidly discharged into a long conduit. The shock resultant from the initiator opened the closure prior to ignition of the ignition aid. In this paper, we report results from both quasi‐static computations for static pressure and time‐dependent simulations for dynamic pressure. Designers need to consider both static and dynamic pressure when devices have a sudden high‐pressure gas released into a conduit.

The effect of 5-amino-1H-tetrazole on the combustion performance and ignition capability of boron/potassium nitrate igniter

The performance of boron/potassium nitrate/5-amino-1H-tetrazole-based pyrotechnic igniter, used as an initiator in airbag gas generators, was investigated. It was found that 5-amino-1H-tetrazole could significantly improve the stability, burning characteristics and ignition capability of boron/potassium nitrate igniter. When mixed with mass ratio of 27/73/10, boron/potassium nitrate/5-amino-1H-tetrazole showed an activation energy of 396.90 kJ mol−1. When used to ignite the guanidine nitrate and basic cupric nitrate gas-generating agent, it resulted in an increase by 19 % in the maximum pressure, as well as a decline in the burning time and ignition delay time by 12 and 24 %, respectively.

IMPROVEMENT OF A TURBINE ENGINE START BY AN EXTERNAL OXYGEN-RICH GAS GENERATOR

Starting of turbine engines is often required under ambient temperature and pressure that are far from their design values. Under such conditions, less air enters the combustion chamber, precluding more fuel to be burned, and making it difficult to produce sufficient energy to accelerate the engine up to idle speed. Common solutions introduce additional oxygen into the combustion chamber to enable more fuel to burn and improve the combustion efficiency, thus providing more energy to the hot gas driving the turbine to accelerate the rotor. Adding oxygen also enables faster and more reliable starting of turbine engines, even under adverse ambient conditions. Conventional oxygen-addition units require storage and supply systems, which pose a great problem for small turbine engines, where space and weight requirements are typically tight, and reliable starting is often needed. The novel approach presented in this paper uses an external module that supplies hot oxygen-rich gas to the combustion chamber, thus providing both oxygen enrichment and ignition of the air-fuel mixture. Consequently, the starting capability of the engine is enhanced. The module’s exterior location enables easy replacement and/or retrofit. Several modes of implementation and their combination are considered. One implementation may use the hot discharge from a pyrotechnic igniter to thermally decompose a solid oxidizer grain, which releases hot oxygen-rich gaseous products. Another implementation may utilize a uniform oxygen-rich solid-propellant grain, releasing hot oxygen-rich combustion products. Preliminary tests with GAP/KP/AP-based oxygen-rich propellant compositions were conducted.

An Investigation of the Performance of a Boron/Potassium‐Nitrate Based Pyrotechnic Igniter

AbstractThe performance of a boron/potassium‐nitrate based pyrotechnic igniter, used as an initiator in airbag gas generators, was investigated at different initial temperatures. Igniter firings were conducted in a small vented combustion chamber in order to measure the instantaneous chamber pressures. A theoretical model, which considers multi‐phase products and lumped chamber parameters, was adopted to determine the discharging gas phase and condensed phase mass flow rates from the igniter. The data reduction model used experimentally obtained pressure‐time traces and the total burned mass as input data. The calculated instantaneous mass flow rates of the igniter at various initial temperatures showed that the initial temperature has a major influence on the igniter's performance. For the temperature range tested (−20 °C to 60 °C), the pressurization rate and the total mass flow rate of the igniter increased with temperature and ranged from 322 GPa/s to 721 GPa/s and 4.3 kg/s to 6.1 kg/s, respectively. It was found that the condensed‐phase products comprised the majority of the igniter discharge products. The mass fraction of the condensed‐phase products indicated a weak dependency on initial igniter temperature. Under similar test conditions, the recorded pressure‐time traces during igniter firings were found to be quite reproducible.

Decomposition flame propagation limits of ethylene and mixtures with other gases

The minimum pressures required for ethylene to propagate a decomposition flame were found at 40, 120 and 280°C in six-inch diameter pipe. Pressure limits found using a anovel “starburst” pyrotechnic igniter array were confirmed as true values using a 75:25 ethylene-oxygen flame cannon. By producing simultaneous initiation across the pipe cross-section, these ignition systems simulated extensive heat sources in process equipment such as adiabatic compression of a trapped diatomic gas, external fire exposure, and runaway reaction in a purifier bed. Heat losses from the nascent flame caused by flame stretch, buoyancy and other effects were minimized. The limits at 40°C, 120°C and 280°C (440 ± 5, 368 ± 8 and 250 ± 10 psia) are about one-half the lowest literature values. The pressure limit varies linearly with temperature and is given by P (psia) = 468 - 0.784* T where T is temperature (°C). The limit was extrapolaed to the derived autodecomposition curve, yielding a complete ignition diagram for ethylene decomposition. Flame speeds were less than 2 ft/s with a typical value of 1 ft/s. The new data explain several reported incidents [15] in this pressure range and underline the potential for decomposition in ethylene purification systems. The data support the practice of blowing down intermediate pressure ethylene to about 150 psi to extinguish flames in hot equipment while avoiding metal embrittlement caused by decompression cooling. Addition of up to 50 mol% hydrogen to ethylene at 120°C progressively lowered the ignition energy; the pressure limit found using 5 kJ “point” ignition sources fell with increased hydrogen. Conversely, the “true” limit found using the starburst array remained similar to ethylene alone (380 ± 10 psia) at up to 25% hydrogen but increased to 490 psia at 50% hydrogen, showing that the latter is a weak diluent. Maximum pressures, pressure rise rates and flame speeds were slightly lower than for pure ethylene. Carbon, hydrogen and methane decomposition products tended to an equilibrium composition with only about 1% ethane. The limit data help explain reported explosions in ethylene-hydrogen mixtures at initial pressures less than 450 psi [15]. Numerous process materials including bed packings and high surface area iron may create hot spots via catalytic hydrogenation of ethylene, hence the lowering of ignition energy by hydrogen can be a hazardous feature. Nitrogen proved to be an effective diluent forethylene-hydrogen mixtures; cases examined with respect to low pressure polymerization reactors displayed pressure limits above 700 psia. Propylene is an effective diluent in binary mixtures with ethylene despite its small positive heat of formation; the pressure limit at 120°C was greater than 600 psia at 57% ethylene. Literature values for the upper flammability limit (UFL) of ethylene in oxygen were critically reviewed. UFL literature data are increasingly unreliable above 90% ethylene owing to igniter limitations. The condition that the UFL must equal 100% ethylene at the observed pressure limit enabled the UFL to be estimated at about 120°C and pressures above 50 psia, where the UFL variation was approximately linear. Ignition sources having insufficient ignition energy may give results that are not only non-conservative, but also have the wrong trend. “Limits” from such studies are not true limits of flammability but only loci at which the igniter system dissipates sufficient power density for ignition. Statistically-based limit modeling of high ignition energy systems may be particularly prone to error, especially if data are extrapolated. An example, based on the UFL findings, is prediction of the limiting oxidant concentration in high pressure process streams based on “low ignition energy” test data. In order to determine true propagation limits for high ignition energy systems, careful attention must be given both to the ignition source and test vessel. Increased ignition energy should not progressively change the observed limit. Especially for slowly developing flames such as ethylene, igniter arrays are more efficient than “point” igniters and can simulate the most severe cases for plant equipment. The test vessel should be large enough to prevent “overdriving” by the ignition source and minimize quenching of the developing flame. The starburst igniter array described in this paper revealed true limits in a six foot long, six inch diameter test pipe, but had an upper operability limit of 125°C and required a significant correction for the overpressure it produced. At temperatures above 125°C, flame initiation was necessary owing to the thermal limitations of pyrotechnics. A 26 foot long test pipe was used to minimize overpressure effects of the flame cannon, which were similar to those observed for the starburst in the 6 foot long pipe. Over-pressure effects were negligible using the starburst in the 26 foot long pipe and this was the preferred system for test temperatures up to 125°C.

Improving the Safety of a Pyrotechnic Igniter through a controlled experiment

AbstractOne of the important goals of quality management in today's competitive marketplace is to build quality into products and processes at the development stage. The use of statistically controlled experiments, in which several parameters are studied simultaneously, can help accomplish this goal efficiently. This paper describes a case study that illustrates the utility of controlled experiments in product development. The customer required improvements in the safety of a pyrotechnic igniter used in one of the products they purchased. The safety improvements could be met by replacing the “match‐head” initiator by a type IA/IW no fire initiator. However, there was concern that changing the initiator might degrade other important product performance characteristics. A controlled experiment was designed to compare three different initiators, the booster charge and the main charge. The experiment quickly and efficiently pointed to a superior initiator and the optimal charges to maintain high performance with enhanced product safety.

Thermal decomposition of phase-stabilised ammonium nitrate (PSAN), hydroxyl-terminated polybutadiene (HTPB) based propellants. The effect of iron(III) oxide burning-rate catalyst

Phase-stabilised ammonium nitrate (PSAN) and hydroxyl-terminated polybutadiene (HTPB) are the main ingredients of propellants used with success in some pyrotechnic igniter components of the VULCAIN liquid rocket engine for the ARIANE 5. Small amounts of selected additives play an important role in solving some of the problems presented by composite propellants that include ammonium nitrate (AN). Iron(III) oxide (Fe 2O 3), for example, can be used as a burning-rate modifier in PSAN/HTPB propellants and although its effect on the burning rate is well known, its mechanism of action is not well understood. Thermogravimetry (TG), differential thermogravimetry (DTG) and differential thermal analysis (DTA) have been applied to study the slow thermal decomposition of selected compositions to investigate the mechanism of action of Fe 2O 3 as a burning-rate modifier of PSAN/HTPB propellants. The compositions evaluated include PSAN, Fe 2O 3 and HTPB cross-linked with isophorone diisocyanate (IPDI) as ingredients. No effect of Fe 2O 3 on PSAN decomposition is found. Fe 2O 3 shows an effect on the kinetics of the first stage of HTPBIPDI decomposition and increases the exothermicity of HTPBIPDI decomposition. In the decomposition of PSAN HTPBIPDI Fe 2O 3 propellants, the effect of Fe 2O 3 is also observed and a synergetic interaction between PSAN and HTPBIPDI is found, for which a physical-chemical explanation is given.

Optimization of a pyrotechnic igniter with the release of reactive particles

This paper deals with the effects of reactive particles on the performance of a pyrotechnic igniter. These particles are placed on the inner surface of a “flash tube”, released into the main flow of the gas and ignited by the passage of one of the two discontinuities (the shock wave or the contact surface). Two particle sizes have been studied (3μm and 10μm). It is shown that the best performance is achieved with small particles released into the flow by the shock wave. Another focal point of this study is the combining of two fundamentally different methods to calculate the two phase flow.