Numerical Analysis of Suppression Effect of Asymmetric Slit on Cavitation Instabilities in Cascade

Abstract

In this study, numerical analysis is carried out around the cyclic flat-plate cascade with symmetric and asymmetric slit, so as to examine the suppressing or controlling effect of the slit on cavitation instabilities such as cavitation oscillation (CO) which resembles cavitation surge, and rotating cavitation. These instabilities cause various problems for the turbomachinery, for example, rotating cavitation causes an asynchronous shaft vibration, and CO causes an oscillation of column of working fluid as a result of the resonance phenomenon of the system. In liquid propellant rocket engine, suppression device for these instabilities bring increase in cost of the launch. Therefore, it is thought that to develop effective suppression technique is important for turbopumps. Especially, in this paper, two types of the flat-plate three blades cascade which have symmetric slit on each blade and three types of the cascade which have asymmetric slit were analyzed, and the results are compared with those of cascade without slit. As a result, the CO is perfectly suppressed in both of two types cascade with asymmetric slit. Also, other examined cascades have suppression effect of CO These results indicate the possibility of suppressing cavitation instabilities in actual inducers or controlling the type of the cavitation instabilities by the arrangement of the slit. Moreover, the head performance is equal or slightly increased by arranging slit.

Influence of Charging Oil Condition on Torque Converter Cavitation Characteristics

“…However, cavitation number is not useful for assessing cavitation degree among different charge oil configurations. For instance, although (7) the cavitation number for the P-T clearance case ranked the highest among all calculated samples (Figure 17), this case suffered from severe cavitation. The P-T clearance was located at the largest radius of the torus (Figure 1), and the pressure dropped significantly with a decreasing torus radius as a result of decreased centrifugal pressure (Figure 10).…”

“…These trends require higher flow velocity in the torque converter, which leads to lower local pressures and thus greater cavitation risk [4,5]. Cavitation has plagued fluid machinery for centuries [6,7], degrading performance and introducing noise, vibration, and even failure depending on the cavitation degree [8]. Considerable research effort has been devoted to the understanding of cavitation mechanism and suppression of cavitation effects [9][10][11].…”

Numerical analysis of the effect of slit shape on the performance and cavitation instability of liquid rocket inducer

“…In our research grope, we have investigated the new suppression technique of the cavitation instabilities by using slits on blades of the inducer from the experimental and numerical methods. In previous studies, numerical analysis of unsteady cavitation in the slit in three-blade cyclic cascade [8,9], experiments on the inducer with asymmetric slits in each blade [10], and experiments on an inducer with the symmetric slits in each blade [11] showed that the slit suppressed the amplitude of oscillation of cavitation instabilities. After that, numerical analysis was performed on inducers with the same slit shape but different slit positions [12].…”

Influence of Charging Oil Condition on Torque Converter Cavitation Characteristics

“…These trends require higher flow velocity in the torque converter, which leads to lower local pressures and thus greater cavitation risk. Cavitation has plagued fluid machinery for centuries [2] [3], degrading performance and introducing noise, vibration, and even failure depending on the cavitation degree [4]. Considerable research effort has been devoted to understanding the cavitation mechanism to enable suppression of its effectys [5][6] [7].…”