Decoy Flares Research Articles

고체/액체 혼합 입자 분사에 의한 항공기 노즐의 다상 유동에 관한 전산 해석

Infrared (IR) signals from the hot exhaust gases of aircraft engines have a significant impact on the survivability of aircraft. Several methods were developed to reduce IR signatures to avoid tracking by IR signatures generated in the exhaust, or decoy flares are used to deceive IR seekers. Research into injecting water particles to lower the exhaust gas temperature or injecting carbon particles to shield the plume has also been previously conducted. In this study, we propose a method for injecting solid/liquid mixed particles that lower the exhaust gas temperature and block IR signal propagation generated in the exhaust gas. The multiphase flow in aircraft nozzles by solid/liquid mixed particle injection was analyzed using the CFD code for the total flow rate of particles corresponding to 5%, 10%, and 20% of the exhaust gas flow rate. After analyzing the characteristics of the mixed particles interacting with the exhaust plume, the optimal flow rate of water and carbon particles with a small thrust penalty was obtained.

Investigation of the Ignition of MTV Decoy Flares

Investigation of the Ignition of MTV Decoy Flares

GF-KCF: Aerial infrared target tracking algorithm based on kernel correlation filters under complex interference environment

Aerial infrared target automatic tracking technology is the core technology of the photoelectric coun-termeasure system of infrared imaging missiles. The correlation filter (CF) tracker has attracted considerable attention in the field of aerial target tracking owing to its excellent performance in tracking accuracy and timeliness. We propose a correlation filter tracking based on Gabor filter (GF) features (GF-KCF) in the frequency domain for aerial infrared target tracking. This tracker constructs a set of frequency-domain GFs, which effectively suppress background noise and highlight target texture information. In view of the large overload maneuver and rapid deformation of aerial infrared targets in the process from near to far distance, we propose a scale estimation method in the frequency-domain based on GF features. The eigenvectors of the target spectrum scale are extracted to improve the accuracy of target scale information estimation. To address the problem of partial occlusion of targets by infrared decoy flares, we propose an anti-interference tracking strategy based on a high-confidence patch model. High-confidence patches are used to track the reliable part of the target, which provide more target information and improve the robustness of the algorithm in case of reappearance of the occluded target. Compared with other trackers, the average accuracy of the proposed tracker was improved by 15.2%, and the frame frequency reached above 110 Hz.

Superior spectral performance of decoy flares compositions via inclusion of graphite as a black body emitter

Graphite particles can offer high interfacial surface area as well as high emissivity as black body; therefore it can find wide applications in advanced decoy flares. In the current study, graphite particles of 100 µm size, were employed with different reactive metal fuels including Mg, Al, and Mg-Al alloy. Different formulations based on graphite ratio up to 8 wt % were developed via granulation with subsequent pressing. Thermal signature was measured using IR spectrometer (1-6 µm) Arc-Optics. Composite flare based on Mg-Al fuel, and graphite demonstrated superior spectral intensity; this formulation offered an increase in average intensity by 83 % to reference MTV flare. In the mean time, composite flare based on Al and graphite offered the highest relative intensity value θ of 0.6. Graphite, as an allotrope of carbon, can act as an excellent source of carbonaceous materials; that can strengthen incandescence emission. Furthermore Mg-Al reactive metal alloy can offer novel synergism as Mg could vaporize at 1000 °C offering efficient combustion process. It can be concluded that tailored flare with customized thermal signature can be developed.

Effects of Mg Al Alloy Powder on the Combustion and Infrared Emission Characteristics of the Mg Al PTFE Viton Composition

Metal-Fluorocarbon compositions are the pyrotechnic formulations which have been widely used in infrared decoy flares to protect aerial targets from infrared guide missile seekers. In this work, the effect of Mg-Al alloy powder (i.e. the particle size and the content) on the combustion and the infrared emission characteristics (i.e. the infrared emission distribution and the infrared radiance) of the pyrotechnic composition based on Mg-Al alloy, polytetrafluoroethylene (PTFE) and Viton rubber are described. The results show that the high burning rate (with the values of 4.0 mm.s-1 to 10.0 mm.s-1, depend on the compression density) of this composition is achieved with a high content of Mg-Al alloy or when using fine Mg-Al alloy particles as well as coarse PTFE particles. On the other hand, the infrared emission radiance (in the wavelength range of 2.5 μm to 5.0 μm) of Mg-Al/PTFE/Viton composition reaches maximum values (i.e. 17.7 W.cm-2.Sr-1 and 21.0 W.cm-2.Sr-1 with the size of Mg-Al particles are 20 μm and 120 μm, respectively) at 60 wt% Mg-Al alloy. Finally, the Mg-Al/PTFE/Viton composition has a similar combustion and emission characteristics as the Mg/PTFE/Viton composition.

Synergism of nanothermite and nanophosphrous compound for advanced infrared flares with superior spectral performance

ABSTRACT Hydroxyapatite (HA) is one of the most common biocompatible material with high phosphorous content (18.5 wt %). HA is thermally stable compound that requires high temperature to decompose; upon decomposition active phosphorus can offer enhanced thermal signature for effective countermeasure of infrared missiles. High reaction temperature can be accomplished via high energy density materials such as nanothermites. This study reports on the facile synthesis of Fe2O3 nanoparticles (5 nm average particle size) and HA nanoplates (530 nm length, 140 nm width) using hydrothermal synthesis. Whereas ferric oxide was employed for nanothermite reactions, HA was employed as phosphorous source material. The effect of developed nanomaterials on thermal signature of traditional Magnesium/Teflon/Viton (MTV) decoy flare was evaluated using Arc-Optics IR spectrometer (1–6 µm). Whereas Fe2O3 (8 wt %) offered enhanced average intensity value by 67%; synergism between HA and Fe2O3 particles offered enhanced spectral performance by 97%. Key radiometric performance parameter is the relative intensity ratio Ɵ(Ɵ = Iα/ Iβ); synergism between HA and Fe2O3 offered superior radiometric performance with Ɵ value of 0.59; this value is similar to aircraft value. This novel spectral performance shaded the light on HA as novel phosphorus material for advanced infrared countermeasure flares.

Multi-component nanocomposite infrared flare with superior infrared signature via synergism of nanothermite and reduced graphene oxide

Infrared-guided missiles caused 90% aircraft damage. Infrared decoy flares are effective counter measure against infrared missiles. Decoy flare thermal signature depends mainly on black body emission of carbonaceous combustion products. Thermite particles can offer substantial heat output to promote black body emission. Reduced graphene oxide (RGO) is a promising material for advanced infrared decoy flares. RGO could act as ideal black-body emitter with superior thermal properties and high interfacial surface area. This study is dedicated to investigate novel synergism between Fe2O3 and RGO; Fe2O3 NPs of 3.56 nm were fabricated using hydrothermal synthesis technique. RGO nano-sheets of 10 µm dimensions and 10 nm thickness were developed via the reduction of graphene oxide, developed by Hummer method. Complete reduction of GO to RGO was confirmed by Raman spectroscopy. Amorphous nano-sheets structure was observed using TEM; XRD diffractogram demonstrated tiny characteristic broad peak for amorphous RGO. Decoy flare formulation based on Fe2O3, RGO, reactive metal fuel (Mg), and fluorocarbon polymer (teflon) were developed. Thermal signature was evaluated using Arc-Optics IR spectrometer (1–6 µm). Multi-component MTV nanocomposite flare based on 6 wt % RGO and 2 wt % Fe2O3 demonstrated superior spectral and radiometric performance. It offered an increase in average intensity by 130% to reference MTV formulation; additionally it offered superior relative intensity Ɵ value of 0.76. While RGO could act as novel black body emitter; thermite reaction between Fe2O3 NPs and surplus magnesium fuel could provide substantial heat output; that could promote RGO black body emission.

Reduced graphene oxide: a novel black body emitter for advanced infrared decoy flares

ABSTRACT Reduced graphene oxide (RGO) possesses unique thermal and optical properties. It could act as black body emitter with high-infrared emissivity. RGO could meet wide applications in advanced infrared decoy flares. In this study, RGO nano-sheets were synthesized through the reduction of GO after applying Hummers’ method using graphite powder as a precursor. The synthesized RGO owns 10 µm dimensions and 10 nm thicknesses. TEM analysis revealed the amorphous structure of the prepared nano-sheets. XRD diffractogram demonstrated the amorphous RGO structure. Moreover, Raman spectroscopy confirmed the complete reduction of GO into RGO. In addition, decoy flare formulations based on RGO, reactive metal fuels, and fluorocarbon polymer were developed. Additionally, thermal signature was evaluated using Arc-Optics IR spectrometer (1–6 µm) to reference formulation. Our results revealed that nanocomposite flare based on 6 wt % RGO demonstrated superior spectral intensity with an increase in average intensity by 147%. Moreover, advanced radiometric performance with superior relative intensity value (Ɵ) of 0.7 was recorded. To sum up, RGO can act as an excellent source of carbonaceous materials that can strengthen incandescence emission. Surplus magnesium could vaporize and combust with substantial heat output that could promote black body emission.

Optimization of compressive strength of MTV decoy flare pellets by Taguchi method

Magnesium/Teflon/Viton or MTV based pyrotechnic composition has been the most preferred composition for decoy flares against conventional heat-seeking missiles for more than four decades. MTV flares of standard configurations are available globally but the details of their manufacturing process including compacting pressure and compressive strength of the flare pellets have not been explicitly defined. The pellets are sub-assembly of the flares dispensed in flight and are critical for successful operations of the decoy flares. Hence, in the present paper, an attempt has been made to optimize the process parameters namely charge mass (A), applied load (B) and dwell time (C) which are responsible for performance variation of compacted standard configuration cylindrical pellets of 50 mm diameter. Each of the process parameters has been considered for three levels. L27 array has been selected to represent these parameters and their interactions. The Taguchi robust experimental method arrived at the optimal result as A1B3C3 (100 g of charge mass, 78.48 KN of applied load and 20 s of dwell time). Analysis of Variance (ANOVA) highlighted that applied load followed by charge mass significantly influenced the density of the pellets. Finally, general regression equation was derived with R 2 value of 0.936 and validated with experimental results.

Novel nanocomposite decoy flare based on super-thermite and graphite particles

Graphite has attracted scientific interest due to its exceptional physical and chemical properties. On combustion, graphite particles offer high emissivity as a black body; therefore, it can find wide application in advanced decoy flares. Thermite particles (metal oxides/metal) can offer a high reaction temperature that is required to stimulate emitting species. In this study, graphite particles were employed with super-thermite Fe2O3 NPs. Novel Mg–Al bimetal alloy was employed as a reactive metal fuel; Viton A (fluorocarbon polymer) was employed as an energetic binder. Multi-component nanocomposite flares were developed via granulation with subsequent pressing. The thermal signature was measured using the IR spectrometer. Nanocomposite flares based on 6 wt% graphite and 2% Fe2O3 NPs demonstrated superior spectral intensity. This flare formulation offered an increase in average intensity by 248% to reference formulation. It offered the highest relative intensity value θ of 0.54. Graphite, as an allotrope of carbon, acts as an excellent source of carbonaceous materials that can strengthen incandescence emission.

Performance evaluation of mechanically pressed Magnesium/Teflon/Viton (MTV) decoy flare pellets

Infra-red decoy flares constituting of Magnesium, Teflon and Viton or MTV, is the most widely acceptable off-board counter measures among majority of the defence forces across the world. These flares are essentially pyrotechnic compositions operating in the range of 3–5µm wavelength owing to the selective emission of the combustion products (MgO, MgF2 and oxides of carbon namely CO and CO2). However, literature on manufacturing techniques and performance characteristics of standard configurations flare pellets developed and supplied by few firms globally is somewhat restricted. Hence, this study is an attempt to evaluate the performance of mechanically pressed 50 mm diameter cylindrical MTV pellets. While varying the process parameters viz. charge mass and applied load for pelleting, the cross-sectional area of the pellets and dwell time of applied load have been maintained constant. With increase in applied load, elastic/brittle fracture of the particles occur which increases surface area of contacts between particles. The optimum density was achieved at 8 tons of load. Similarly, the improvement in density with increase in charge mass was observed till L/D ratio of unity was achieved. SEM images confirmed the increase in contact surfaces and reduction in size of particles owing to elastic/brittle fracture. With increase in applied load, the available surface area decreased and there was a conspicuous increase in burn time. With increase in charge mass, the quantity of pyrotechnic mixture available for burning increased leading to increase in burn time.

Infrared Spectra of Customized Magnesium/Teflon/Viton Decoy Flares

Infrared (IR) guided missile is known to cause 90% of aircraft damage. Magnesium/Teflon/Viton (MTV) decoy flares are customized materials, which are capable of yielding thermal signature to interfere with IR guided missile seekers. In this study, the IR-signature of an MTV flare is measured in a jet engine nozzle. The jet engine IR-signature is characterized with two characteristic peaks over the α-band (2–3 µm) and β-band (3–5 µm); this is correlated to black body emission at 690° C. The MTV decoy flare with 65% Mg offers an increase in the average intensity of the α- and β-bands by 21 and 4 times, respectively, to that of the jet engine. Quantification of emitting species in the combustion flame is conducted by using the ICT thermodynamic code. The developed MTV formulation offers the relative intensity ratio of the α- and β-bands equal to 0.96, which is comparable to that of an aircraft (0.7).

Optimisation of density of infra-red decoy flare pellets by Taguchi method

Magnesium/Teflon/Viton or MTV pyrotechnic composition has been widely preferred to prepare decoy flares as countermeasures against heat seeking Infra-red (IR) missiles. Though MTV for military applications are available in the global market, the manufacturing process and performance characteristics of these flares have not been explicitly defined. The pellets which are an essential sub-assembly of the flares need to be extensively studied to develop these flares for military applications. The study paper attempts to optimise the density of compacted 50 mm diameter cylindrical pellets. The pyrotechnic composition is initially subjected to various sensitivity tests namely impact, friction and spark to assess the threshold values of initiation of this composition. Three levels of process parameters for pelleting have been considered and L27 array has been selected to represent the process parameters namely charge mass (A), applied load (B), dwell time (C) and their interactions. The Taguchi robust experiment method arrived at the optimal result as A1B3C3 (100 g of charge mass, 8 tons of applied load and 20 s of dwell time). Analysis of Variance (ANOVA) highlighted that parameters A and B significantly influenced the density of the pellets. Finally, general regression equation was derived with R2 value of 0.94.

Investigations of Process Parameters on the Mechanical Properties of MTV Decoy Flare Pellets for Defence Applications

The Infrared (IR) guided missiles have posed serious threats to aircrafts flying even at considerably high altitude. An effective counter measure to this imminent threat of the heat seeking missiles is IR decoy flares constituting of Magnesium/Teflon/Viton (MTV) based pyrotechnic composition. The provisioning of MTV flares primarily for defence applications globally is controlled by very few foreign firms who have ensured that the manufacturing techniques and performance parameters are closely guarded owing to economic as well as strategic reasons. Hence, there are limited research papers available which illustrates the mechanical pressing of the MTV composition to form pellets and the performance evaluation of these pellets.The present paper is an attempt to study the density of 50 mm diameter pellets by varying the charge mass of pellets and the applied load to compact the MTV composition. The applied load is varied in steps of 1 ton for a fixed pyrotechnic charge mass mixture of 100 gm for a fixed dwell time of 15 seconds. It is observed that the density of pellets increased with increase in application of load up to an applied load of 8 tons. This phenomenon is owing to reduction in porosity of the mixture as well as brittle fracture of magnesium particles facilitating optimisation of density of pellets. Similar phenomenon was observed by varying the charge mass and the optimum density was obtained for a L/D ratio nearing unity. Thus, the range of process parameters which is found to be of interest for development of pellets of this dimension is 100 gm to 140 gm of charge mass and 6 tons to 8 tons of applied load.

Cancer Self-Defense: An Immune Stealth.

The hurdles in realizing successful cancer immunotherapy stem from the fact that cancer patients are either refractory to immune response and/or develop resistance. Here, we propose that these phenomena are due, in part, to the deployment/secretion of a "decoy flare," for example, anomalous cancer-associated antigens by the tumor cells. The cancer secretome, which resembles the parent cell make-up, is composed of soluble macromolecules (proteins, glycans, lipids, DNAs, RNAs, etc.) and insoluble vesicles (exosomes), thus hindering cancer detection/recognition by immunotherapeutic agents, resulting in a "cancer-stealth" effect. Immunotherapy, or any treatment that relies on antigens' expression/function, could be improved by the understanding of the properties of the cancer secretome, as its clinical evaluation may change the therapeutic landscape. Cancer Res; 77(20); 5441-4. ©2017 AACR.

The influence of accelerated aging on magnesium/PTFE/FPM decoy flares

The influence of accelerated aging on magnesium/PTFE/FPM decoy flares

The Infrared Spectra of Customized Magnesium/Teflon/Viton (MTV) Decoy Flares to Thermal Signature of Jet Engine

Decoy flares are customized materials, which are capable of yielding thermal signature to interfere with IR guided missile seekers. In this study, different decoy flares compositions based on Magnesium/Teflon/Viton (MTV) (with fuel percentage ranging from 40:70 wt %) were developed by granulation and subsequent pressing. The spectral performance of developed decoy flare formulations was measured to thermal signature of jet engine nozzle using (FT-MIR 2-6) spectrophotometer. The jet engine thermal signature was characterized with two characteristic peaks over α band (2-3μm) and β band (3-5μm); this signature was correlated to black body emission by the nozzle at 690 0C. Absorption of the IR emission by air could attenuate the signal over the band 3-4 μm due to CO2 and H2O IR absorption. The characteristic intensity ratio of jet engine nozzle (α/ β) = 0.26 . The developed decoy flares offered similar thermal signature but with higher intensity due to the formation carbon soot and MgF2 as black body and active IR emitter respectively. Quantification of these emitting species in the combustion flame was performed using the ICT thermodynamic code. MTV decoy flare with 65 wt % Mg offered an increase in the intensity of α band and β by 21 and 4 times respectively. This customized formulation offered the formation of MgF2 (molecular emitter) and C soot (grey emitter) at 42.4, and 8.8 wt % respectively. It is also offered 48 wt % Mg fuel which would be oxidized in the flame and add much more heat with the formation of MgO (grey body). The characteristic intensity ratio Ɵ was found to be 0.96. This is manuscript would open the route for the development of customized decoy flares with tailored spectral performance.

The Infrared Spectra of Customized Magnesium/Teflon/Viton (MTV) Decoy Flares to Thermal Signature of Jet Engine

The Infrared Spectra of Customized Magnesium/Teflon/Viton (MTV) Decoy Flares to Thermal Signature of Jet Engine

Ignition and combustion of pyrotechnics at low pressures and at temperature extremes

Abstract Rapid and effective ignition of pyrotechnic countermeasure decoy flares is vitally important to the safety of expensive military platforms such as aircraft. QinetiQ is conducting experimental and theoretical research into pyrotechnic countermeasure decoy flares. A key part of this work is the development and application of improved models to increase the understanding of the ignition processes occurring for these flares. These models have been implemented in a two-dimensional computational model and details are described in this paper. Previous work has conducted experiments and validated the computational model at ambient temperature and pressure. More recently the computational model has been validated at pressures down to that equivalent to 40,000 feet but at ambient temperature (∼290 K). This paper describes further experimental work in which the ignition delays of the priming material in inert countermeasure decoy flares were determined for pressures down to 40,000 feet and at temperature extremes of −40 °C and 100 °C. Also included in this paper is a comparison of the measured and predicted ignition delays at low pressures and temperature extremes. The agreement between the predicted and measured ignition delays is acceptable.

Temperature measurements of magnesium- and aluminum-based flares

Experimental researches were performed in order to determine the combustion temperatures and the visible and infrared screening performances of two pyrotechnic compositions used in decoy flare systems. Morphostructural and morphochemical analyses of the combustion solid products have been correlated with the combustion temperature. For the experimental studies, visible and infrared thermography have been employed, together with dedicated software. The comparative measurements indicated that the thermovision camera enables the acquisition of more accurate results versus the optical pyrometer in terms of data processing, and that the aluminum/polyhalogenated compounds–compositions present visible and infrared screening performances superior to those based on magnesium/polyhalogenated compounds.