CAJ | 학술논문

对于非设计工况下流体机械的流场计算，由于其偏离设计工况，分离流动严重等特点，使得用普通的湍流模型数值模拟精度不高。本文采用一种将涡粘性系数Cμ与湍流脉动动能和湍流耗散率的变化相关联的方法，对RNG k-ε湍流模型进行修正。为验证其对非设计工况下叶片泵的预测精度，分别采用修正模型和原始RNG模型，数值模拟了一比转速为439的叶片泵的内部流场，得到了其扬程、效率曲线及在典型工况下的内部流场流线分布。通过比较改进前后RNG湍流模型的数值计算结果，并与实验结果对比，得出修正RNG模型更能准确预测出非设计工况下叶片泵的流场特性。
대우비설계공황하류체궤계적류장계산，유우기편리설계공황，분리류동엄중등특점，사득용보통적단류모형수치모의정도불고。본문채용일충장와점성계수Cμ여단류맥동동능화단류모산솔적변화상관련적방법，대RNG k-ε단류모형진행수정。위험증기대비설계공황하협편빙적예측정도，분별채용수정모형화원시RNG모형，수치모의료일비전속위439적협편빙적내부류장，득도료기양정、효솔곡선급재전형공황하적내부류장류선분포。통과비교개진전후RNG단류모형적수치계산결과，병여실험결과대비，득출수정RNG모형경능준학예측출비설계공황하협편빙적류장특성。
Numerical simulation with normal turbulence model could not predict the internal flow of fluid machinery precisely under the off-design operations because of the severe separated and secondary flow under those conditions. This paper has modified the RNG k-ε turbulence model by associating the eddy-viscosity value with the change of turbulent kinetic energy and turbulent dissipation. In order to validate the improved turbulence model, the internal flow of a centrifugal pump which the specific speed equals to 439 has been simulated with the modified RNG k-ε turbulence model and original RNG model respectively. Based on the numerical simulation, the head and efficiency curve and also the internal flow streamlines distribution under typical operations was obtained. With the comparison of numerical and experiment results, it is noted that the modified RNG k-ε model could predict the performance of centrifugal pump under off-design operations more precisely compared to original model.