矿井通风系统扩散器性能与结构优化研究

发布时间：2018-09-12 21:02

【摘要】：针对当前矿井通风系统扩散器结构阻力大和由此导致通风系统风机效率低的问题,提出了双切流线型扩散器,形成了该扩散器结构及其参数的优化方法,优化了扩散器流场,改善了该扩散器的性能,提高了矿井通风系统的效率。首先,在深入调查研究的基础上,总结了矿井通风系统节能技术研究进展,找出了存在的问题,发现优化扩散器是实现矿井通风系统节能的重要途径。应用能量守恒和质量守恒原理,界定了结构及其参数对扩散器流场的影响特性,量化了流场与扩散器性能的关系。应用流体力学理论,推导出了扩散器理想静压率、实际静压率、结构阻力系数和净收益率等计算式,建立了扩散器性能评价体系。其次,设计了双切流线型扩散器。根据现场技术要求和行业安全规范,扩散器具有轴向长度短、曲线壁面和大转角出流的工程约束,应用速度势函数,得到了非均匀平面平行来流与虚拟汇叠加的扩散器内流流场势函数;利用柯西-黎曼条件,导出该势函数的共轭流函数;利用边界条件,解析出流线型轮廓线方程;利用预设松弛因子控制流线型轮廓线曲率增加率的工程近似,得到了扩散器内轮廓线和外轮廓线方程。在所得内轮廓线和外轮廓线的基础上,设计了一种由引导线、流线型壁面曲线和延长线构成的新型曲线壁面扩散器。而后,优化了双切流线型扩散器结构参数与流场。通过数值计算,得出双切流线型扩散器具有更合理的内流流场和出流流场。以实际静压率、结构阻力系数、净回收率为评价指标,优化了双切流线型扩散器结构,得出优化的断面扩大系数为2.20至2.35之间。建立了实验平台及自动测量系统,针对三个不同结构及其参数变化的双切流线型扩散器性能开展实验测试,获得了最佳性能的扩散器,优化了双切流线型扩散器的结构及其参数,得到最优断面扩大系数为2.28。通过数值计算,得到了双切流线型扩散器渐扩断面上的动量系数和动能系数,归纳出动量系数和动能系数随雷诺数变化的跃升过渡流区,并得出该过渡区主要受矩形断面宽高比的影响;相比外轮廓线,内轮廓线上的边界层厚度和压力梯度的沿程变化更平缓;来流速度越大,边界层厚度和压力梯度沿程波动幅度和频度越大;扩散器形体参数偏离优化值越大,边界层厚度和压力梯度波动幅度和频度越大,结合实验数据,得出出流断面上的流场越不稳定。因此,优化的流场能改善扩散器性能,性能的提升依赖于扩散器结构及其参数的优化来实现。最后,形成了矿井通风扩散器性能与结构参数优化的方法。在工程边界约束下,利用理论演绎,改进了扩散器结构设计方法;利用数值计算,优化了扩散器结构;利用数值计算和模型实验,优化了扩散器结构及其参数;最终,形成了以性能参数为评价指标的双切流线型扩散器结构及其参数优化方法。
[Abstract]:In view of the large resistance of diffuser structure in mine ventilation system and the low efficiency of fan in ventilation system, a double tangent streamline diffuser is put forward, which forms the optimization method of the diffuser structure and its parameters, and optimizes the diffuser flow field. The performance of the diffuser is improved and the efficiency of mine ventilation system is improved. Firstly, on the basis of deep investigation and research, this paper summarizes the research progress of mine ventilation system energy saving technology, finds out the existing problems, and finds out that optimizing diffuser is an important way to realize mine ventilation system energy saving. Based on the principles of energy conservation and mass conservation, the influence of structure and its parameters on diffuser flow field is defined, and the relationship between flow field and diffuser performance is quantified. Based on the hydrodynamics theory, the formulas of ideal static pressure rate, actual static pressure rate, structural resistance coefficient and net return rate of diffuser are derived, and the performance evaluation system of diffuser is established. Secondly, a double tangent streamline diffuser is designed. According to field technical requirements and industry safety specifications, diffusers have engineering constraints of short axial length, curve wall and large corner outflow, and apply velocity potential function. In this paper, the potential function of flow field in diffuser is obtained, the conjugate flow function of the potential function is derived by using Cauchy Riemann condition, and the streamline contour equation is analyzed by using boundary conditions. The engineering approximation of the curvature increase rate of streamline contour is controlled by the preset relaxation factor, and the internal and external contour equations of diffuser are obtained. On the basis of the inner and outer contours, a new type of curve wall diffuser composed of guide line, streamline wall curve and extension line is designed. Then, the structure parameters and flow field of double tangent streamline diffuser are optimized. Through numerical calculation, it is concluded that the double tangent streamline diffuser has more reasonable internal flow field and outlet flow field. The structure of double tangent streamline diffuser is optimized by taking the actual static pressure ratio, structural resistance coefficient and net recovery rate as evaluation index, and the optimized cross section expansion coefficient is between 2.20 and 2.35. The experimental platform and the automatic measurement system are established. The performance of the double tangent streamline diffuser with three different structures and its parameters is tested, and the diffuser with the best performance is obtained. The structure and parameters of double tangent streamline diffuser are optimized, and the optimum expansion coefficient is 2.28. Through numerical calculation, momentum coefficient and kinetic energy coefficient on the expanding section of double tangent streamline diffuser are obtained. It is concluded that the transition zone is mainly affected by the ratio of width to height of the rectangular section, the thickness of boundary layer and the pressure gradient on the inner contour are more gentle than those of the outer contour, and the velocity of the flow is greater. The greater the fluctuation amplitude and frequency along the boundary layer thickness and pressure gradient, the greater the fluctuation amplitude and frequency of the diffuser body parameters deviating from the optimized value, the greater the fluctuation amplitude and frequency of the boundary layer thickness and pressure gradient. It is concluded that the flow field on the flow section is more unstable. Therefore, the optimized flow field can improve the diffuser performance, and the performance improvement depends on the optimization of the diffuser structure and its parameters. Finally, the optimization method of performance and structure parameters of mine ventilation diffuser is formed. Under the engineering boundary constraint, the design method of diffuser structure is improved by theoretical deduction, the diffuser structure is optimized by numerical calculation, and the diffuser structure and its parameters are optimized by numerical calculation and model experiment. A double tangent streamline diffuser structure and its parameter optimization method based on performance parameters are developed.
【学位授予单位】：湖南大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：TD724

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