固、液导体中第二相微颗粒的电磁探测

It exists several important applications of the electromagnetic approach for inspecting and measuring micro-scale particles being as secondary phase embedded or suspended within the solid or liquid conductor in the areas of In situ, online, quantitative liquid metal quality control in metallurgy industry and solidification engineering, non-destructive testing (NDT), automatically inspecting and controlling technologies in the metal materials service, etc. The applicant propose a method of Lorentz force particles analyzer (LFPA) based on the electromagnetic inducting principle for the first time, The present results prove the correctness of the principle and confirm the technological feasibility. It has several distinguishing superiorities in comparing with the other traditional NDT methods, one of them is its contactless principle. The applicant demostrate the correctness on the principle and technical feasibility. Generally, this topic is a synthesized problem which involves in the knowledge of electromagnetism, magnetohydrodynamics, multiphase and microfluids flow, surveying (particularly in tiny force measurement) comprehensive multi-disciplinary. We plan to theoretically, experimentally and numerically investigated this project applied. On the theoretical side, this project intends to develop electromagnetically detecting principle by means of the electromagnetic quantities not only of Lorentz force acting upon the magnet-generating-system, but also of electromagnetic torque, static magnetic force, verification of frequency domain characteristics et al; The project also intends to develop semi-analytical solution using magnetic dipole; On the experimental side, the project devotes to solve the essential problems applying in different application domains mentioned above using Lorentz force particles analyzer principle; On the numerical analysis side, multiphysics models involving in multiphase, microfluids and electromagnetic field are built to describe the transient physical phenomena. The expected findings and results are expected to enrich the theory of metallurgy and solidification engineering, electromagnetic induction, electro- hydrodynamics, surveying and other disciplines, for instance, the physical behaviors and rules of the micro-particles flowing in the microfluids in magnetic field. In sum, this project fulfills with both important academic values and broad application prospects.

固、液导体中第二相微颗粒的电磁探测方法，在金属液纯净度在线监测、无损检测等领域都有着重要应用。申请人首次提出了基于电磁感应原理的洛仑兹力微颗粒探测方法。确认了原理上的正确性和技术上的可行性。本法可对固、液导体中的微颗粒的尺寸和频度（或浓度）进行可靠的定量监测。由于采用了非直接接触的原理，与传统的库尔特微颗粒测量法相比具有显著优势。本研究是一个涉及电磁学、磁流体力学、多相微流、测量学等学科的综合问题。本研究理论上发展电磁感应探测原理，建立以磁偶极子作为理论解析工具的解析、半解析模型；实验上致力于解决应用中的关键科技问题；数值上求解电磁和多物理场耦合的问题，其中多物理场涵盖多相、微流等。预期结果将丰富电磁学、磁流体力学、冶金与凝固工程、测量学等学科的基础与应用理论，尤其是含微颗粒的固、液导体在电磁场中的物理行为与规律，获得有实用价值的成果。因而本项目兼具重要的学术价值和广阔的应用前景。

本课题探索了一种新的用于检测导电流体流动中的微米级绝缘颗粒的非接触式技术。通过施加渗透到导体中的磁场，测量作用在磁系统上的洛伦兹力（主要是与相对运动方向的分量。通过测量到的脉冲信号可以确定微颗粒数量和定量尺寸。采用移动网格的数值技术建立了的二维的多物理场数值模型。通过两个原型实验和三维数值模型研究了洛伦兹力微颗粒测量仪。.关键数据如发表JAP杂志上的表，第一列表示微颗粒的等效直径，从中可见我们探索了从4毫米直至10微米，最后一列为采用要测量的洛仑兹力的量级，可见所需测量的力的量级直至微牛量级。因此，在本课题的研究我们努力测量该量级的微小力，换言之，微小力测量是本课题的重要任务。在本课题中采用了类似于原子力显微镜的原理，即激光-悬臂梁机构来测量微小力，所不同的是，在机构里采用了永磁体作为磁源，因此测量系统变为激光-悬臂梁-永磁体系统。 .课题研究结果表明：洛仑兹微颗粒测量方法具有在线、定量的特点，可以有更广泛的应用。这些应用包括测量高温和具有侵蚀性的熔融金属（如铝和钢合金）的洁净度，以及制造高纯度的半导体。