• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
• /
• 2002.10b
• /
• pp.323-324
• /
• 2002

This paper presents a preliminary study of the influence of roughness due to marine propeller blades machining on their performance. A blade surface finish that has been roughened by corrosion, cavitation and other phenomena, leads to a power penalty. Thus propellers manufacturers tend to propose blades of great surface finish, even mirror-polished. However achieving such surface finish increases manufacturing costs. With modem manufacturing means, propellers can now be machined while preserving a good surface finish. We have studied the influence of manufacturing strategy on an aspect of hydrodynamic performance, cavitation.

• The KSFM Journal of Fluid Machinery
• /
• v.17 no.3
• /
• pp.25-32
• /
• 2014

The main objective of this study is to validate the performance characteristics of newly developed micro propeller turbine based on experimental model test. For this purpose, Measurements of efficiency and cavitation tests with variations on the guide vane opening, blade rotational speed, head and load are carried out according to the IEC standard for model testing. From the tests and scale up calculation, the maximum prototype and model efficiency of the runner blade reaches as high as 90.87 % and 90.27 % respectively. Test results show that good cavitation behavior is covered in the range of output 50kW and 100 kW.

• Aerospace Engineering and Technology
• /
• v.10 no.1
• /
• pp.122-128
• /
• 2011

A series of water tests of a Lox pump for liquid rocket engines are performed at a room temperature. According to the hydraulic test results, the head coefficient is slightly decreased when the rotational speed of the pump is increased. However the efficiency is high at the high-speed test. Also, according to the cavitation test results, the cavitation performance of the pump is found to be decreased when the flow ratio is less than 92%. Furthermore, the vibration characteristic is analyzed using measured high frequency data.

• Journal of Advanced Marine Engineering and Technology
• /
• v.17 no.3
• /
• pp.42-49
• /
• 1993

Recently, because the lubricating oil showed a tendency to be emulsified and oxidized by high speed, high output and the extension of maintenance & conservation of marine engine, the cavitation erosion-corrosion at such an environment became a big problem on effective performance of engine. Therefore, there was a need to study the behavior and protection of erosion-corrosion damage, and then applied inhibitor to a protective method of cavitation erosion- corrosion damage. At this time, test environments were marine lubricating oil & various emulsified oil that mixed distilled water and sea water etc., and also used 20KHz, 24.mu.m piezoelectric vibrator as an experimental apparatus of cavitation erosion. With this apparatus, we investigated an influence of the emulsified oil on characteristics of erosion-corrosion and protection for erosion-corrosion by inhibitor at slide bearing metals.

• Journal of the Society of Naval Architects of Korea
• /
• v.37 no.1
• /
• pp.10-25
• /
• 2000

The effects of Reynolds number of model propeller leading edge roughness and air content resolved in tunnel water on cavitation inception, cavitation extent and pressure fluctuation were investigated experimentally by using two model propellers in a cavitation tunnel. Cavitation observation and propeller induced fluctuating pressure measured in the present model test were compared with the model test results of other research institutes and the full-scale data of a German container ship(Sydney Express). The comparison shows a reasonable agreement.

• Journal of the Society of Naval Architects of Korea
• /
• v.37 no.2
• /
• pp.14-21
• /
• 2000

The cavitation noise of 2-D hydrofoils is measured a cavitation tunnel. A new experimental method was developed for the noise measurement of 2-D hydrofoil. Three hydrofoils with the span of 600mm are designed and manufactured to investigate cavitation behavior and noise characteristics. The experimental results show the noise characteristics of various cavitation patterns and the noise performance of the three foils very well. This suggests that low-noise propeller blade section can be developed using the present experimental method.

• Journal of the Society of Naval Architects of Korea
• /
• v.37 no.2
• /
• pp.22-29
• /
• 2000

The cavitation noised of high-speed propellers was experimentally studied in KRISO cavitation tunnel. In this paper, a series of cavitation noise tests were carried out for five propellers with various sections and loading distributions. From the experimental results, the noise characteristics of various cavitation pattern and the noise performance of the propellers were analyzed. There can be used for optimum design for high-speed propellers.

• The KSFM Journal of Fluid Machinery
• /
• v.16 no.2
• /
• pp.27-34
• /
• 2013

As the operating range of centrifugal pump is expanded recently, the various suction conditions are demanded. The most important problem in the suction conditions is cavitation. In this study, to analyze the characteristics for such the cavitation, first the validity of the numerical analysis was certified through comparison with the experimental result of performance curve according to flow rate for the industrial centrifugal pump. At this time, the transient numerical analysis for the full type model of the centrifugal pump was performed to get more accurate results. The numerical analysis on the cavitation of centrifugal pump were conducted on the two-phase flow as the same method of one-phased flow.

• Nuclear Engineering and Technology
• /
• v.30 no.1
• /
• pp.40-46
• /
• 1998

A set of experiments using a 1/10 scale model pump which was manufactured to simulate performance of reactor coolant pump(RCP) of Y.G.N # 3 and 4, was executed in single phase(at atmospheric pressure and room temperature) and near-saturation(300 ~ 600kPa). The pump characteristics in single phase flow was similar to the characteristics of the RCP. The pump characteristic curves at nearly saturated state were correlated in terms of flow coefficient and head coefficient for subcooled temperature using the cavitation number defined as (equation omitted), which can be predicted the cavitation possibility. The pump behavior around the saturated temperature almost consists with single phase behavior until the cavitation occurs(When cavitation occurs. When the flow coefficient is about 0.12), the pump head rapidly degrades. In this situation, subcooled temperature is about 1.8~8$^{\circ}C$ and cavitation number of model pump is 1.0 ~ 1.7.

• Journal of Mechanical Science and Technology
• /
• v.16 no.2
• /
• pp.246-254
• /
• 2002

Recent primary concern for the design of high performance heat exchanger and highly integrated electronic equipments is to develop an active and creative technologies which enhance the heat transfer without obstructing the coolant flows. In this study, we found through the LDV measurement that the gaseous cavitation induced by ultrasonic vibration applied to the CO$_2$saturated water in the square cross-sectioned straight duct flow enhances the turbulence much more than the case of non-ultrasonic or normal ultrasonic conditions without gaseous cavitation does. We also found that gaseous cavitation can enhance effectively the turbulent heat transfer between the heating surfaces and coolants by destructing the viscous sublayer.