CAJ | 학술논문

为优化和扩大旋进旋涡流量计的计量范围，通过CFD方法，采用RNGk-ε湍流模型进行数值模拟并结合试验对150 mm口径的旋进旋涡流量计进行了研究。首先对起旋器入射角为57.5°的流量计进行了非定常数值计算，由于气体速度较低，在数值计算时不考虑气体的压缩性，计算结果能够反映压力损失的实际变化，流量计仪表系数的数值模拟结果与试验值基本吻合。通过试验验证了所采用的数值方法能对流量计的性能进行较好的预测。为进一步分析起旋器入射角度对旋进旋涡流量计压力损失和仪表系数的影响，对3种起旋器入射角度55°、57.5°和60°下的旋进旋涡流量计内部流场进行了三维数值模拟，对比分析了不同入射角下旋进旋涡流量计内部流场分布以及压力损失和仪表系数随流量的变化特性。研究结果表明：流体流经起旋器后压力会迅速下降，旋涡中心的压力相对较低，在喉部以前区域压力沿轴向基本成对称分布；发现起旋器入射角越大，流量计压力损失越大；起旋器入射角度对仪表系数有一定的影响，起旋器入射角越大，仪表系数越大。起旋器入射角度为55°时，旋进旋涡流量计性能最好。
위우화화확대선진선와류량계적계량범위，통과CFD방법，채용RNGk-ε단류모형진행수치모의병결합시험대150 mm구경적선진선와류량계진행료연구。수선대기선기입사각위57.5°적류량계진행료비정상수치계산，유우기체속도교저，재수치계산시불고필기체적압축성，계산결과능구반영압력손실적실제변화，류량계의표계수적수치모의결과여시험치기본문합。통과시험험증료소채용적수치방법능대류량계적성능진행교호적예측。위진일보분석기선기입사각도대선진선와류량계압력손실화의표계수적영향，대3충기선기입사각도55°、57.5°화60°하적선진선와류량계내부류장진행료삼유수치모의，대비분석료불동입사각하선진선와류량계내부류장분포이급압력손실화의표계수수류량적변화특성。연구결과표명：류체류경기선기후압력회신속하강，선와중심적압력상대교저，재후부이전구역압력연축향기본성대칭분포；발현기선기입사각월대，류량계압력손실월대；기선기입사각도대의표계수유일정적영향，기선기입사각월대，의표계수월대。기선기입사각도위55°시，선진선와류량계성능최호。
In order to optimize and expand the measure range of the swirl meter with 150 mm diameter, the incident angle of swirler is investigated to improve the performance of swirl meter. The internal flow fields of the swirl meter with different swirler incident angles are numerically simulated using RNG k-ε turbulence model based on CFD (computational fluid dynamics) technique. The pressure loss, instrument coefficient and the distribution of flow field are comparatively analyzed for the swirl meters. First, under the flow rates of 120, 300, 750, 1 200 and 2 100 m3/h, the numerical simulations and experiments are carried out to study the pressure loss characteristics and instrument coefficient of the swirl meter with 150 mm diameter when the incident angle of swirler is 57.5°. The commercial software Gambit is used to obtain the numerical mesh, and the structured and unstructured grids are used for different regions which take both calculation speed and accuracy into consideration. In the process of calculation, FLUENT software is used for the numerical simulation, and the RNGk-ε turbulence model is adopted considering its better prediction ability in complex unsteady flow condition; besides, the inlet boundary condition is set as velocity inlet, and the outlet boundary condition is set as outflow, which assumes the flow is fully developed. The medium of simulation is air and the density is 1.225 kg/m3; moreover, for the maximum velocity of air in this study is about 33 m/h (when flow rate is 2 100 m3/h) which is much less than Mach 0.3, therefore, the air is considered as incompressible fluid during the simulation. The experiment research is completed by sonic nozzle calibration device under a standard atmospheric pressure and the temperature of 24℃. The numerical results are in good agreement with the experimental ones, and therefore, the numerical method adopted in this paper is proved to be feasible for the research of swirl meter and can save lots of time in the future study. It is appropriate to use computational fluid dynamics method to investigate the influence of different incident angles (57.5°, 55° and 60°) on the pressure loss and instrument coefficient for swirl meter, and the design of swirl meter could be more efficient than ever by using CFD technique. As a result, two more swirlers at the incident angle of 55°and 60° are calculated with the same numerical method and geometrical model except for the incident angle. By comparing the pressure loss, instrument coefficient and pressure distribution of three swirl meters, it is found that the larger incident angle is, the bigger pressure loss of swirl meter will be. It is also found that the change of incident angle has some influence on the instrument coefficient, and the larger incident angle is, the larger instrument coefficient will be. As larger incident angle brings stronger vortex, the smaller minimum flow value can therefore be measured by swirl meter. By analyzing the pressure contour distribution of three models, it is found that the pressure drops quickly at the swirler region and leads to part of pressure loss, the lowest pressure is at the center of vortex and the distribution is nonuniform at throat and diffuser region, while the pressure becomes steady at the end of deswirler. As a whole, the swirl meter with swirler incident angle of 55° comes with the best performance.