An endoscopic PIV method is provided that combines an endoscope and PIV to overcome optical path restrictions and allows for fine presentation of important flow field information within a water jet propulsion pump. Then the measurements of water jet propulsion pumps’ inlet, impeller and vane, outlet flow fields have completed by the endoscopic PIV. The practicality and correctness of the endoscopic PIV are verified by analyzing the pattern and characteristic of flow field, comparing results of the conventional PIV method. Technical assistance is provided for the development of high-performance water jet propulsion pump through this study.
Water jet propulsion is a new type of marine propulsion device with high efficiency, strong anti-cavitation ability, good maneuverability, low operating noise, and a wide range of variable operating conditions, which is currently developing in the direction of high speed, light weight, and quietness (Wu, 2012). However, researchers have yet to fully comprehend the complex flow structure within the water jet propulsion pump, and there are significant limits in the understanding of impeller and vane interference, as well as fluid-structure coupling (Yan et al., 2022).
An advanced non-contact flow field measuring method based on optical image correlation analysis is called particle image velocimetry, or PIV for short (Wei et al., 2021). In a laboratory setting, the casing can be setted viewing window or manufactured directly from transparent Plexiglas, however the field of vision distortion induced by refraction between several media makes it impossible for PIV to collect more precise information about the flow field within the water jet propulsion pump directly. A combination of PIV and endoscope is attempted, based on the established applications of endoscopic techniques in endoscopy, minimally invasive surgery, and in-cylinder viewing. We propose an endoscopic PIV flow field measurement method for water jet propulsion pumps and have completed measurements of a 300mm-inner-diameter water jet propulsion pump's inlet, impeller and vane, and outlet flow fields. The practicality of the endoscopic PIV method and the correctness of the results are verified through the analysis of the flow pattern and characteristics of the flow field and the comparison of the results of the conventional PIV test. The research results provide reliable experimental means for water jet propulsion pumps’ design optimization of high-performance, vibration and noise reduction, momentum conversion mechanism and flow structure-induced dynamic problems.
