Interaction between Uneven Cavity Length and Shaft Vibration at the Inception of Synchronous Rotating Cavitation

Asymmetric cavitation is known as one type of the sources of cavitation induced vibration in turbomachinery. Cavity lengths are unequal on each blade under condition of synchronous rotating cavitation, which causes synchronous shaft vibration. To investigate the relationship of the cavity length, fluid force, and shaft vibration in a cavitating inducer with three blades, we observed the unevenness of cavity length at the inception of synchronous rotating cavitation. The fluid force generated by the unevenness of the cavity length was found to grow exponentially, and the amplitude of shaft vibration was observed to increase exponentially. These experimental results indicate that the synchronous shaft vibration due to synchronous rotating cavitation is like selfexcited vibrations arising from the coupling between cavitation instability and rotordynamics

An aberrant right hepatic artery arising from the gastroduodenal artery: a pitfall encountered during pancreaticoduodenectomy.

Among the variations of the right hepatic artery (RHA), the identification of an aberrant RHA arising from the gastroduodenal artery (GDA) is vital for avoiding damage to the RHA during surgery, since ligation of the GDA is necessary during pancreaticoduodenectomy (PD). However, this variation is not frequently reported. The purpose of this study was to focus on an aberrant RHA arising from the GDA, which was not noted in the classifications reported by Michels and Hiatt. A total of 574 patients undergoing a PD between Jan 2001 and Dec 2015 at a tertiary care hospital in Switzerland (n = 366) and between Jan 2009 and May 2015 at a hospital in Japan (n = 208) were included in the analysis. Of these, preoperative CT angiography or/and MRI angiography findings were available for 532 patients. We retrospectively analyzed the hepatic artery variations, patient demographics, and surgical outcomes. Among the 532 patients who received a PD, an RHA originating from the GDA was observed in 19 cases (3.5%). Eleven patients (2.1%) had both an aberrant RHA and an aberrant left hepatic artery (LHA) (Hiatt Type 4). Six patients (1.2%) had a replaced CHA arising from the SMA (Hiatt Type 5). We could, therefore, correctly identify the aberration in all cases. We observed rarely reported but important aberrant RHA variations arising from the GDA. To prevent injury during PD in patients with this type of aberrant RHA, intensive preparations using CT and/or MRI imaging before surgery and intraoperative liver Doppler ultrasonography are considered to be essential