基于引射器原理的投砾装置喷嘴CFD优化仿真分析

Optimization CFD Simulation Analysis on the Nozzle of Gravel Delivery Device Based on Ejector Principle

摘要:

地浸钻孔成井工艺中，目前常用的投砾设备主要有渣浆泵与各类自制投砾装置。基于引射器原理的投砾装置是一种现场应用较广的投砾装置，为了提高该投砾装置的工作效率和投砾质量，本文基于计算流体力学的数值模拟软件Fluent对引射器原理的投砾装置的引射器结构进行了数值模拟的优化分析。分析结果表明，引射器喷嘴直径对引射效果具有较大影响，引射器的引射系数随喷嘴直径的增大而逐渐减小，但较小的喷嘴直径会导致对泥浆泵的泵压负荷增大，对于现场使用的BW250型泥浆泵，要求最高压力≯6 MPa，因此引射器喷嘴的直径为5 mm时为最优值；混合室直径增大会降低引射器性能，根据砾料通过能力等确定最优参数为18 mm；混合室长度有利于提高引射器性能，本文优化值为120 mm长度时为较佳混合室管长。优化后的投砾装置较原有基于大喷嘴直径引射器的投砾装置，投砾效率和质量均有大幅提高。

Abstract:

In the completion process of in-situ leaching borehole, the common gravel delivery equipments used at present are mainly slurry pump and non-subject gravel delivery devices. The gravel delivery device based on the ejector principle has wide range of field application, in order to improve its working efficiency and delivering quality, the optimization analysis is made on the numerical simulation of ejector structure of gravel delivery device based on the ejector principle by employing numerical simulation software Fluent based on computational fluid dynamics in this paper. The analysis results show that the diameter of the nozzle has great influence on the performance of the ejector and the injection coefficients of ejector decrease with the increase of ejector nozzle diameter, but the smaller nozzle diameter will lead to the increase of pump pressure load of mud pump. For BW250 mud pump used in the field site, the required maximum pressure is not greater than 6MPa, so the optimal nozzle diameter in the study is 5mm in this case. For the increase of the mixing chamber diameter will reduce the performance of the ejector, the optimal parameter is determined as 18mm based on gravel passing capacity and some factors; the appropriate increase of the length of mixing chamber is beneficial to improve the ejector performance, ideal length of 120mm is decided after optimization. The delivery efficiency and quality of optimized delivery device are greatly improved than those of original delivery device based on ejector with large diameter nozzle.