Pressure Loss of a Cylindrical Intake and its Reduction

This paper presents a basic study on pressure loss of a cylindrical intake (inner diameter=2R=200mm, wall thickness=t=25 or 50mm), where measurements were made under the conditions of Reynolds number being (1.0-1.4)×105 and external/internal velocity ratio being 0-0.29 for each of the following three intake-lips:(a) quarter round lip (Type A: t/R=0.25), (b) semi-circular lip (Type B: t/R=0.25). and (c) semi-circular lip (Type C: t/R=0.50). From the experimental results, it is clarified that the curvature of intake inner-wall is a key factor to secure the good fl uid-dynamic performance. Each pressure loss was correlated with the wall pressure distribution and the separation region. The latter was favorably v isualized with the distribution of back-flow fraction measured with a split film probe. Further, it is demonstrated that the reduction of pressure loss was achieved by installation of a backward-facing-ramp type bar in the separation region of Type B intake, which is regarded as a new method for separation control.