| Flammable liquid and solid fuels are widely used in civil and national defense industry.The explosion of gas-liquid,gas-solid two-phase mist is one of the major disasters in the industrial production process.At the same time,the mists as the explosion energy,how to improve the explosive intensity is an urgent need to solve the major issue in national-security research.In this work,Gas-liquid,gas-solid two-phase mists as the research object,The concentration,turbulence of gas-liquid,gas-solid two-phase mists and its explosion physical characteristic are studied through experiment and theoretical method.The results and main innovative contributions of the thesis are briefly described below:In order to study the explosion mechanism of mists,the measurement system on transient concentration,particle size of mists,and on the transient turbulence fields were developed.It is the key to the basic research on mist's explosion,which to design the measurement system for a transient mist's field.Based on the demand of multiphase explosion mechanism,through a variety of comparisons and analysis with the measuring methods of particle size,concentration,and on the basis of the principle of optical scattering method,we design the measurement system on transient concentration,particle size of mists.The sampling time is less than 1 ms,the deviation measurement of particle size is less than 1 u m,the measurement deviation of concentration is less than 5%.Ultimately,the measurement system adapted to multiphase mist's explosion mechanism,to solve the important basic subject for observation and analysis of transient mists,and it provides an important method for the mist's explosion research.Using the technical advantages about accurate characterization of the flow field on PTV,combined with the needs of observation and analysis on the flow field characteristics of multiphase mists,and successfully designed the measurement system for the transient turbulence fields.Through the comparison of a variety of particle matching algorithm,and combined with the characteristics of transient mists,to realize the particle matching calculation in flow fields by particle matching probability method,solved the design key technology for the high speed flow field,computation's efficiency and precision.Using sliding the least square method,the interpolation calculation from the vector data in the flow field is implemented,and the accurate results are obtained.By montecarlo numerical simulation method,the system of reliability and suitability,the results were verified.The measurement system for the transient turbulence implements the observation of transient flow field by the non-contact,to the further study on the interaction of turbulence and explosion provides a new approach.The coupling law over the concentration and turbulence,the mechanics characteristic of the explosion on gas-liquid two-phase mists are researched by the methods of experiment and theory.The related laws for the particle size and the physical mechanical properties on mists are derived.The rules within the explosion limits,the pressure and temperature,the minimum ignition energy on n-alkane mists is revealed.The correlation model for the minimum ignition energy and the particle size,the explosion parameters and turbulence are established.Williams and Polymeropoulos are verified by this experiment on mist's explosion intensity increases with specific particle size scale.The results show: the lower explosive limits of n-hexane,n-heptane,n-octane,n-decane on mists and their number of C element are linear relationship.N-alkane mist's lower explosive limits with the increase of particle size increase.The minimum ignition energy for the particle size of 40 ?m on n-alkane mists than the minimum ignition energy of gas-phase n-alkane,increased by two orders of magnitude.With micron and nano aluminum powder and micron,nano hybrid aluminum powder as the research object,explore the dispersed physical characteristics of aluminium dusts,the dispersed essential difference between micron and nanometer aluminum powder is revealed.The results show: To the nano aluminum powder under different pneumatic pressure,rather than the nano aluminum powder intrinsic characteristics under the scanning electron microscope(SEM),the difference on the particle size have two order of magnitude.So nano aluminum powder has obvious aggregation effect,there is essential difference with micron aluminium powder.With micron and nano powder as the research object,Combined with the physical properties of the gas-solid two-phase dispersion,the physical characteristics of the explosion and the maximum effective burning velocity on micron and nano aluminum powder dust cloud under turbulent flow are studied.The law for the explosion parameters change with the turbulence intensity is derived,and the physical characteristic of mist's explosion under different turbulence is revealed.The results show: The explosion overpressure peak for micron,nano aluminum powder with the increase of the turbulence increase linearly.The explosion overpressure peak value for nano aluminum powder is greater than micron aluminium powder under the condition of same turbulence intensity.The agglomerating force between nano aluminum particles has an inhibitory effect for the increased rate of maximum overpressure.With the increase of turbulence intensity,the influence of the agglomerating force is weakening for the increased rate of maximum overpressure. |
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