• Proceedings of the KSME Conference
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• 2001.06e
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• pp.619-624
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• 2001

A performance test facility for turbopump inducer cavitation was developed and the inducer cavitation performance tests were performed. Major components of the performance test facility are driving unit, test section, piping, water tank, and data acquisition and control system. The maximum of testing capability of this facility are as follows: flow rate - 30kg/s; pressure - 13 bar; rotational speed 10,000rpm. This cavitation test facility is characterized by the booster pump installed at the outlet of the pump that extends the flow rate range, and by the pressure control system that makes the line pressure down to vapor pressure. The vacuum pump is used for removing the dissolved air in the water as well as the line pressure. Performance tests were carried out and preliminary data of test model inducer were obtained. The cavitation performance test and cavitation bubble flow visualization were also made. This facility is originally designed for turbopump inducer performance test and cavitation test. However it can be applied to the pump impeller performance test in the future with little modification.

• Journal of the Society of Naval Architects of Korea
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• v.60 no.1
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• pp.1-9
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• 2023

In order to improve the propeller cavitation performance composed of Cavitation Inception Speed (CIS), cavitation extent and pressure fluctuation, it needs to improve the wake distribution that flows into the propeller. The warship propeller cavitation is strongly influenced by the wake created at the V-strut of various appendages. The inflow characteristics of the V-strut were investigated using Computational Fluid Dynamics (CFD) and the twisted angles of the V-strut were aligned with upstream flow. The resistance and self-propulsion tests for the model ship with the existing and modified V-struts were conducted in Towing Tank (TT), and wake distribution, CIS, cavitation observation and pressure fluctuation tests were conducted in Large Cavitation Tunnel (LCT). The propeller behind the modified V-strut showed better cavitation characteristics than that behind the existing V-strut. Another model test was conducted to investigate rudder cavitation performance by the change of the V-strut. The rudder cavitation characteristics were not improved by the change of the operating conditions. On the basis of the present study, it is thought that the stern appendages for better propeller cavitation performance would be developed.

• Aerospace Engineering and Technology
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• v.8 no.1
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• pp.26-31
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• 2009

Three Lox pumps and one fuel pump are manufactured for turbopump real-propellent tests and water tests of the pumps are performed in order to estimate the performance characteristics of the pumps. According to the test results, the test region(flow ratio, cavitation number) of the pumps at the water tests cover the operating region at the real-propellent tests and also all the pumps satisfy the design requirement. The head of the Lox pumps shows a 2% difference among them due to the internal geometry, but the efficiency and overall cavitation performance are almost same. It is found that the fuel pump has a similar head and efficiency compared with the previous model of the same internal geometry, while it has a little inferior cavitation performance.

• Journal of the Society of Naval Architects of Korea
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• v.46 no.6
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• pp.569-577
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• 2009

As the scale factor of model propellers utilized in cavitation test is about 40, it is difficult to find out practical countermeasures against the small area erosions on the blade tip region throughout model erosion tests. In this study, a partial propeller blade model was used for the observation of cavitation pattern for the eroded propeller. A partial propeller blade model was manufactured from 0.7R to tip with expanded profile and with adjustable device of angle of attack. Reynold's number of a partial propeller blade model is 7 times larger than that of a model propeller. Also, anti-singing edge and application of countermeasures to partial propeller blade model which produced in large scale can be more practical than a model propeller. For the observation of cavitation at high Reynold's number, high speed cavitation tunnel was used. To find out the most severe erosive blade position during a revolution, cavitation observation tests were carried out at 5 blade angle positions.

• Aerospace Engineering and Technology
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• v.4 no.1
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• pp.143-149
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• 2005

To evaluate the hydraulic and cavitation performance of a fuel pump for a liquid rocket engine, performance tests of the pump, which consist of hydraulic tests and cavitation tests, were conducted in water environment with various condition. In the hydraulic tests, the head, efficiency and volute pressure distribution of the pump are found to follow the conventional similarity rule, whereas the secondary flow pressure shows a small deviation from the similarity rule. As the floating gap is constricted, the efficiency of the pump improves and the secondary flow pressure decreases. However, the inner diameter of bypass line orifice does not show clear relationship with the pump efficiency. In the cavitation tests, measurements of the head and the NPSH indicate that the pump shows better cavitation performance as the rotational speed of the pump increases.

• Special Issue of the Society of Naval Architects of Korea
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• 2005.06a
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• pp.44-50
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• 2005

Since a cavitation pattern in model scale can be different from that in full scale, it has been highly demanded to measure a fluctuating pressure induced by propeller in full scale. For the verification of the cavitation test for 105K lanker in the large cavitation tunnel in Samsung Ship Model Basin(SSMB), an effective pressure fluctuation measurement system was developed and a series of full scale measurements was carried out. These results were compared with those of cavitation tests in SSMB. The measured results in full scale gave good agreements to those in model tests. The fluctuating pressure at $2^{nd}$ blade frequency in full scale seems to be highly dependent upon tip loading.

• Journal of the Society of Naval Architects of Korea
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• v.43 no.5 s.149
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• pp.578-585
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• 2006

Cavitation related erosion damages on semi-spade rudder generally occur at around leading edge of lower-face and behind gap of lower pintle. To get the idea of gap entrance profile for the latter case, a series of tests with large models has been carried out at MOERI. In the tests, the flow pattern around lower pintle have been investigated and visualized by high speed camera. Additionally, cavitation inception tests and pressure measurements have also been conducted for better comparison. As a result a new model (F rudder) has been developed. The new model turned out to have stable pressure distribution along the surface and so the cavitation inception speeds within ${\pm}5^{\circ}$ of rudder angle were delayed approx. 4 knots in average.

• International Journal of Naval Architecture and Ocean Engineering
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• v.4 no.3
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• pp.322-334
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• 2012

This paper shows the numerical and experimental results about the hydrodynamic characteristics of X-Twisted rudders having continuous twist of the leading edge along the span. All the results were compared with those of the semi-balanced rudder. Calculation through the Reynolds-Averaged Navier-Stokes Equation (RANSE) code with propeller sliding meshes shows large inflow angle and fast inflow velocity in the vicinity of ${\pm}0.7$ R from the shaft center, so it may cause cavitation. Also, X-Twisted rudder has relatively small inflow angles along the rudder span compared with semi-balanced rudder. For the performance validation, rudders for two large container carriers were designed and tested. Cavitation tests at the medium sized cavitation tunnel with respect to the rudder types and twisted angles showed the effectiveness of twist on cavitation and the tendency according to the twist. And the resistance, self-propulsion and manoeuvring tests were also carried out at the towing tank. As a result, in the case of X-Twisted rudder, ship speed was improved with good manoeuvring performance. Especially, it was found out that manoeuvring performance between port and starboard was well balanced compared with semi-balanced rudders.

• Corrosion Science and Technology
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• v.20 no.6
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• pp.325-334
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• 2021

In the open system (vessel and pipe), the maximum corrosion rate of carbon steel at ca. 80 ℃ was obtained due to the decrease of dissolved oxygen by increasing the solution temperature. Effect of temperature on the cavitation damage can be explained through several mechanisms. Moreover, when cavitation occurs on the surface of metal and alloys, whether cavitation is erosion or corrosion is still controversial. This work focused on the effect of solution temperature on the corrosion of carbon steel under cavitation in an open system, Tests were performed using an electrochemical cavitation corrosion tester in 3.5% NaCl solution and the effect of solution temperature of carbon steel was discussed. Cavitation corrosion rate can be increased by cavitation, but when the temperature increases, a dissolved oxygen content reduces at a very high speed and thus the maximum cavitation corrosion temperature changed from 80 ℃ to 45 ℃. Below the maximum cavitation temperature, the electrochemical effect was more dominant than the mechanical effect by increasing temperature, but over the maximum cavitation temperature, the mechanical effect was more dominant than the electrochemical effect by increasing temperature.

• The KSFM Journal of Fluid Machinery
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• v.8 no.1 s.28
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• pp.23-29
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• 2005

Steady and unsteady cavitation characteristics of turbopump inducer were investigated in this paper. To investigate the effect of blade angle on the inducer performance, three inducers with inlet tip blade angle of $7.8^{\circ},\;7.0^{\circ},\;6.1^{\circ}$, respectively, were tested. For $7.8^{\circ},\;7.0^{\circ}$ inducers in the non-cavitating condition, head decreased linearly with flow rate, but head-flow rate curve had a dip at the flow coefficient ${\psi}=0.065$ for $6.1^{\circ}$ inducer. Attached cavitation and cavitation surge were found in the $7.8^{\circ},\;7.0^{\circ}$ inducers in the cavitation tests. During the attached cavitation one cell rotated at the same rotational speed as that of the inducer. The cavitation surge did not rotate and the oscillating frequency was $7{\sim}20\;Hz$. From the curve of the critical cavitation number versus flow rate, it was found that the steady cavitation performance of $6.1^{\circ}$ inducer was much lower than that of $7.8^{\circ},\;7.0^{\circ}$ inducers.