High-Speed Infrared Radiation Thermometer for the Investigation of Early Stage Explosive Development and Fireball Expansion

Hobbs, Matthew J.; Barr, A.D.; Woolford, S.; Farrimond, Dain; Clarke, Steve; Tyas, A.; Willmott, Jon R.

doi:10.3390/s22166143

Cited by 6 publications

(5 citation statements)

References 30 publications

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“…Hobbs et al . [42] provide details on the specification, design, manufacture and calibration of the IRTs used in this study. Using the ideal gas law theory (equation 6.1), the temperature measurements, T , can be used to infer the temporal development of pressure, P , in a constant volume, V , with the known moles of gas in the chamber, n , and gas constant, R = 8.314 J/(mol K).…”

Section: Inferred Pressure From Temperature Measurementsmentioning

confidence: 99%

“…A bespoke high-speed (250 kHz) infrared radiation thermometer (IRT) was developed that has the ability to measure the temperature of a given medium based on the emitted radiance of a fireball. Hobbs et al [42] provide details on the specification, design, manufacture and calibration of the IRTs used in this study. Using the ideal gas law theory (equation 6.1), the temperature measurements, T, can be used to infer the temporal development of pressure, Experimentally recorded pressure-time history resulting from a 30 g PE10 detonation in air (black -left), argon (blue -centre) and nitrogen (red -right) using pressure gauges and inferred pressures from the IRT using the ideal gas laws.…”

Section: Inferred Pressure From Temperature Measurementsmentioning

confidence: 99%

See 1 more Smart Citation

Experimental studies of confined detonations of plasticized high explosives in inert and reactive atmospheres

Farrimond,

Woolford,

Barr

et al. 2024

Proc. R. Soc. A.

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When explosives detonate in a confined space, repeated boundary reflections result in complex shock interactions and the formation of a uniform quasi-static pressure (QSP). For fuel-rich explosives, mixing of partially oxidized detonation products with an oxygen-rich atmosphere results in a further energy release through rapid secondary combustion or ‘afterburn’. While empirical formulae and thermochemical modelling approaches have been developed to predict QSP, a lack of high-fidelity experimental data means questions remain around the deterministic quality of confined explosions, and the magnitude and mechanisms of afterburn reactions. This article presents experimental data for RDX- and PETN-based plastic explosives, demonstrating the high repeatability of the QSP generated in a sealed chamber using pressure transducers and high-speed infrared thermometry. Detonations in air, nitrogen and argon atmospheres are used to identify the contribution of afterburn to total QSP, to estimate the duration of afterburn reactions and to speculate on the flame temperature associated with this mechanism. Computational fluid dynamic modelling of the experiments was also able to accurately predict these effects. Understanding and quantifying explosions in complex environments are critical for the design of effective protective structures: the mechanisms described here provide a significant step towards the development of fast-running engineering models for internal blast events.

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Section: Inferred Pressure From Temperature Measurementsmentioning

confidence: 99%

Section: Inferred Pressure From Temperature Measurementsmentioning

confidence: 99%

Experimental studies of confined detonations of plasticized high explosives in inert and reactive atmospheres

Farrimond,

Woolford,

Barr

et al. 2024

Proc. R. Soc. A.

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“…Buckling of the pressure bars is prevented by a series of lateral supports fitted with bushings to enable free axial movement and shock absorbers at the base of each bar. The main target plate also features fastening points for a removable blast chamber, which are used to investigate the effects of afterburn through control of the atmospheric gases around the explosive charge [ 25 ], and enable thermal [ 26 ] and chemical [ 27 ] analysis of the detonation products.…”

Section: Experimental Designmentioning

confidence: 99%

Temporally and Spatially Resolved Reflected Overpressure Measurements in the Extreme Near Field

Barr

Rigby

Clarke

et al. 2023

Sensors

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The design of blast-resistant structures and protective systems requires a firm understanding of the loadings imparted to structures by blast waves. While empirical methods can reliably predict these loadings in the far field, there is currently a lack of understanding on the pressures experienced in the very near field, where physics-based numerical modelling and semi-empirical fast-running engineering model predictions can vary by an order of magnitude. In this paper, we present the design of an experimental facility capable of providing definitive spatially and temporally resolved reflected pressure data in the extreme near field (Z<0.5 m/kg1/3). The Mechanisms and Characterisation of Explosions (MaCE) facility is a specific near-field evolution of the existing Characterisation of Blast Loading (CoBL) facility, which uses an array of Hopkinson pressure bars embedded in a stiff target plate. Maraging steel pressure bars and specially designed strain gauges are used to increase the measurement capacity from 600 MPa to 1800 MPa, and 33 pressure bars in a radial grid are used to improve the spatial resolution from 25 mm to 12.5 mm over the 100 mm radius measurement area. In addition, the pressure bar diameter is reduced from 10 mm to 4 mm, which greatly reduces stress wave dispersion, increasing the effective bandwidth. This enables the observation of high-frequency features in the pressure measurements, which is vital for validating the near-field transient effects predicted by numerical modelling and developing effective blast mitigation methods.

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“…As a thermometry technique, non-contact radiation thermometry has been widely adopted in recent years because it does not require contact with the measured object [1][2][3][4][5][6][7]. In order to measure the transient surface temperature of combustion devices such as internal combustion engines and gas turbines, Sneha Neupane et al developed a multi-infraredchannel pyrometry-based optical instrument for high-speed surface thermometry.…”

Section: Introductionmentioning

confidence: 99%

Multispectral Thermometry Method Based on Optimisation Ideas

Zhang,

Liu,

Wang

et al. 2024

Sensors

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Multispectral thermometry is based on the law of blackbody radiation and is widely used in engineering practice today. Temperature values can be inferred from radiation intensity and multiple sets of wavelengths. Multispectral thermometry eliminates the requirements for single-spectral and spectral similarity, which are associated with two-colour thermometry. In the process of multispectral temperature inversion, the solution of spectral emissivity and multispectral data processing can be seen as the keys to accurate thermometry. At present, spectral emissivity is most commonly estimated using assumption models. When an assumption model closely matches an actual situation, the inversion of the temperature and the accuracy of spectral emissivity are both very high; however, when the two are not closely matched, the inversion result is very different from the actual situation. Assumption models of spectral emissivity exhibit drawbacks when used for thermometry of a complex material, or any material whose properties dynamically change during a combustion process. To address the above problems, in the present study, we developed a multispectral thermometry method based on optimisation ideas. This method involves analysing connections between measured temperatures of each channel in a multispectral temperature inversion process; it also makes use of correlations between multispectral signals at different temperatures. In short, we established a multivariate temperature difference correlation function based on the principles of multispectral radiometric thermometry, using information correlations between data for each channel in a temperature inversion process. We then established a high-precision thermometry model by optimising the correlation function and correcting any measurement errors. This method simplifies the modelling process so that it becomes an optimisation problem of the temperature difference function. This also removes the need to assume the relationships between spectral emissivity and other physical quantities, simplifying the process of multispectral thermometry. Finally, this involves correction of the spectral data so that any impact of measurement error on the thermometry is reduced. In order to verify the feasibility and reliability of the method, a simple eight-channel multispectral thermometry device was used for experimental validation, in which the temperature emitted from a blackbody furnace was identified as the standard value. In addition, spectral data from the 468–603 nm band were calibrated within a temperature range of 1923.15–2273.15 K, resulting in multispectral thermometry based on optimisation principles with an error rate of around 0.3% and a temperature calculation time of less than 3 s. The achieved level of inversion accuracy was better than that obtained using either a secondary measurement method (SMM) or a neural network method, and the calculation speed achieved was considerably faster than that obtained using the SMM method.

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High-Speed Infrared Radiation Thermometer for the Investigation of Early Stage Explosive Development and Fireball Expansion

Cited by 6 publications

References 30 publications

Experimental studies of confined detonations of plasticized high explosives in inert and reactive atmospheres

Experimental studies of confined detonations of plasticized high explosives in inert and reactive atmospheres

Temporally and Spatially Resolved Reflected Overpressure Measurements in the Extreme Near Field

Multispectral Thermometry Method Based on Optimisation Ideas

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