小径高比环形叶栅的某些实验条件对实验结果的影响

对1/4环、半环和全环形叶栅在两种出口条件下进行了吹风实验。测量了栅后的静压、总压和子午面内气流倾斜角沿节距和叶高的分布。实验结果表明:在栅后有简体的条件下,半环和全环形的实验结果接近,在进行方案比较时,可采用半环形叶栅。但为使实验结果更好地反映透平中的实际流动,实验叶栅应制成全环形。栅后安装简体可以部分消除大气条件对测量结果的影响。气流自叶栅直接排入大气的条件是不可取的。

Influence of Some Experimental Conditious for Annular Cascades with a Small Diameter-Blade Length Ratio on Their Experimental Results

Blow-down tests of quarter-annular,semi-annular and full-annular cascades were performed under two different outlet conditions. The distribution of the static pressure,the total pressure and the obliquity angle of airflow in the meridional plane along the pitch and the height of a cascade was measured. The experimental results showed that there is no great difference in the performance of a semi-annular cascade and a full-annular cascade when a circular outlet duct is fitted behind the annular cascade. Therefore, when different methods are to be compared with each other, the use of a semi-annular cascade is acceptable. However, in order to make the experimental result of an annular cascade better reflect its actual flowing in a turbine, the trial cascade should be full-annular. If an outlet is fitted behind the annular cascade,the influence of the atmosphere on the experimental results can be partly eliminated. It is not advisable that the airflow be directly exhausted into the atmosphere.