Study On The Cause Tracing Of Airflow Fluctuation And Drift In Mine Ventilation System

As basic data of mine ventilation network calculation, resistances of airways needs to bemeasured accurately through time-consuming work process, which seriously hinders theapplication of ventilation network calculation in mines. Being one of the important functionscovered by Safety Monitoring Systems, systematically operated airflow measurement canreveal a wide range of ventilation information such as changes of resistance distribution.Relevant analysis of airflow data can provide valuable support to the routine application ofmine ventilation calculations, thus promote mine safety management to a higher level.As a tool for engineering problem solving, mine ventilation network calculationsnormally do not have sufficient and accurate data to balance the network while allow theresult fit the in-situ measurement accurately, thus, when applying to a mine, ventilationnetwork solving pursues a rational rather than theoretically accurate solution, and is lack ofrigid rule to follow as well as a clear and definite objective to pursue. This dissertation putsforward a mathematical model to deduce airflow pattern in the system based on limitedmonitoring data of airflow, and further aim at the deduced airflow distribution data to obtainairway resistance data in an optimization process. A two-phase control design is adopted toensure its applicability and reliability with a lower need of operation interference and a higherdegree of rationality, thus opens a door for the technique of ventilation network calculationinto daily safety management.In the dissertation, two concepts of airflow fluctuation and airflow drift are put forwardto mark off airflow variances of different nature. It is pointed out that airflow fluctuationshave the characteristics of white noise sequence while airflow drifts demonstrate thecharacteristics of gradual change sequence. Based on the application of Taylor Series and relevant mathematical theories, a ventilation sensitivity matrix is calculated to aid theidentification of ventilation resistance changes that led the observed airflow changes in thesystem, and the statistical characteristics of airflow and resistance changes can be obtained.The research of this paper shows that the identification capability of cause tracking ofairflow variance has some regional discrepancy within the whole ventilation system. Thiscould influence the uniformity of identification accuracy, and thus could form some localblind areas for identifying which in turn could result in the problem of multi-solutions.Therefore this paper suggests that it is necessary to optimize the distribution of airflowmonitors within the whole ventilation system, putting forward the methods to optimize theconfiguration of airflow monitors based on the analysis of single airway’s airflow change aswell as deal with the multi-solutions problem by setting additional criterions, which enhancethe application accuracy and suitability of cause tracking in a ventilation system.A numerical experiment platform of coal mine ventilation system is designed in thedissertation to verify the proposed model of cause tracing based on relevant theories ofstochastic process and Monte-Carlo method. The numerical experiment platform ofventilation system can effectively provide simulated sceneries of real mine network, thus issuitable for a variety of analysis and verifications relating to mine ventilation, and can bewidely applied in the future.