Research On Technique Of Explosion Flame True Temperature Measurement

Explosion flame temperature is an important parameter that characterizesthe explosive forces of missiles and explosives. Its research has practicalsignificance in the field of national defense, chemistry, and material sciences etc.Because of the destructiveness and instantaneity in the explosion process, it israther difficult to measure the explosion flame temperature. This research,sponsored by funds on the national level, researched on the true temperaturemeasurement technology of the explosive flame so as to lay foundation for theevaluation of explosive force.The existing methods and instruments in the measurement of the explosiveflame true temperature were researched on and improvement was made directingat the existing faults. The multi-spectral pyrometer was successfully developedfor this purpose. For the high temperature calibration, two non-sourcetemperature calibration methods were proposed, one being power-function based,and the other being logarithmic function based. The two methods proposed aresignificant in improving the radiation temperature measurement theory,broadening the measurement range of the pyrometers, and upgrading themeasurement precision of non-source temperature.At present, most radiation pyrometers have the following two faults. First,they can only measure the brightness temperature rather than the true temperaturewhen the emissivity is unknown. The emissivity estimation method usuallyresults in comparatively large error. Secondly, it has low anti-explosion ability,low response speed, low sample rate and narrow measurement range. To solvethe problem mentioned above, a multi-spectral pyrometer was developed tomeasure the true temperature of the explosive flame in this research. Based onthe radiation temperature measurement theory, the Second Measurement Methodand Brightness Temperature Approximation Method were combined to resolvethe theoretical issue in the true temperature measurement. An optical structurewas established to separate the main body of the pyrometer and the opticaltargeting system, which improved the anti-explosion property of the pyrometer.The automatic selection of the measurement range was designed to widen the range of the pyrometer. Automatic activation designed greatly increased theextent of automation of the pyrometer. high-speed synchronized data collectionsystem was developed which improved the response rate and sampling rate. Thewireless transmission and host computer were implemented to ensure the safetyof the personnel.In order to solve the existing problem in the non-source temperaturecalibration, a non-source temperature calibration method was proposed based onthe power function. Since the curve of power function and that of thetemperature-voltage in source temperature region have great similarity, amathematical model was established based on the power function. Since theDerivative Least-Square has high controllability over the shape of the curve, itwas used to obtain the solution of the model so as to realize the non-sourcetemperature calibration. In addition, Plank Law was used to testify the theoreticalprecision of this calibration method. The experimental data collected in thesource temperature range and the theoretical testing in the non-sourcetemperature range were employed to testify the precision of this method in thepractical application. The test results show that the extrapolation temperaturerange is between3100℃and3500℃,and the actual experimental data precisionis greater than0.7%.A calibration method in non-source temperature range was proposed basedon the logarithmic function model. The transfer function of the pyrometer wasused to establish the temperature-voltage curve and the solution to the model wasobtained using derivative Least-Square. The blackbody emissivity and the actualcalibration data of the pyrometer in the source temperature range were usedrespectively to testify the precision of this method. The result shows that thecalibration has both high theoretical precision and satisfactory precision inpractical applications. The extrapolation temperature range is between3100℃and3500℃, and the actual data measurement precision is1.1%.In order to define the applicable condition of the two calibration methods,large amount of simulations were conducted. Through the analyzing the influenceof different wavelengths and the numbers of temperature points on the precisionof the two methods, the wavelength and number of points were determined forthe two methods respectively. Through the analysis of the influence of temperature points at unequal intervals and the range of temperature selection onthe precision of the two methods, the theoretical basis of temperature pointselection was established. Through the analysis of anti-random-error ability ofthe two methods, their applicable precision ranges were determined. Thesimulation results showed that the conditions for the calibration method based onthe power function model could be easily realized and the ability of anti-random-error was strong, while the method based on the logarithmic function modelrequired strict application condition and the ability of anti-random-error wasweak.The blackbody furnace simulation and TNT explosion experiment wereconducted using multi-spectral pyrometer developed in the research. The reactionof this pyrometer to temperature field was tested through rapidly shielding thehigh-temperature blackbody output window to simulate the rapidly changingtemperature field. In the field experiment, the3kg TNT explosive was tested andthe experimental results were analyzed. The uncertainty of the measurement ofthe pyrometer is obtained which is1.2%in the overall measurement range.