• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2006.05a
• /
• pp.135-140
• /
• 2006

In the experimental study of $N_2$ purge cold flow test of impinging(FOOF) injector for determining of instability region, the whistling sound which has a specific frequency is generated. The frequency of whistling is proportional to the gas flow velocity in part of the oxidizer orifice and due to the coupling of the vibrating gas column and the natural frequency of pipe-orifice shape, the discontinuous jumping phenomena arises. The whistling phenomena have no effect on the combustion instability. Compared the damping factor of 1T1L mode with the hot fire test, the instability region of $N_2$ purge cold flow test is very much like that. It means that flow instability by impinging or mixing of jet is the main reason of combustion instability of impinging injector(FOOF) in the hot firing test.

• Journal of the Korean Society of Propulsion Engineers
• /
• v.3 no.4
• /
• pp.44-50
• /
• 1999

For the prediction of combustion performance of the Unlike Impinging Quadlet Injector (OOOF type), mixing efficiency, mixing characteristic velocity, and efficiency of mixing characteristic velocity were obtained from the cold test. Water/kerosene were used for simulants, The momentum ratio of oxidizer and fuel were mixing correlating parameter. Orifice discharge coefficient, spray pattern and mass distribution were measured. As a result, invasion-depth had strong effect on mixing efficiency, mixing characteristic velocity, and efficiency of mixing characteristic velocity. Mixing efficiency and efficiency of mixing characteristic velocity showed maximum value for momentum ratio 1.67(TMR = 2.5), and fuel rich state showed larger decreasing ratio than oxidizer rich state.

• Journal of the Korean Society of Propulsion Engineers
• /
• v.19 no.4
• /
• pp.8-14
• /
• 2015

This study has been done as a preliminary work in the process of confirming the modeling and calculation results on the dynamic characteristics of closed-type swirl injector which were performed by Ismailov et al. in Purdue university. Closed-type swirl injectors with replaceable swirl chamber parts were designed and manufactured. The steady state spray characteristics of closed-type swirl injector with varying swirl chamber length and diameter were verified. Mass flow rate was measured with a mass flow meter installed in front of the injector, and liquid film thickness was measured by Lefebvre's method with electrodes installed at the orifice of the injector. Variation of spray cone angle and break-up length were investigated from the spray images captured under different manifold pressure conditions.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.9 no.4
• /
• pp.135-143
• /
• 1989

The experimental study on the shape and behavior of bubbles in U-tube deep shaft of 32m has been performed. According to the results in this paper, the equivalent spherical diameter of bubbles was 0.422-0.722cm and the shape of bubbles was almost ellipsoidal for bubbles to be generated ta single-orifice of diameter 0.06cm in the downcomer of the deep shaft system. Gas hold-up and gas-liquid contact area of bubbles in the deep shaft was decreased in accordance with depth, Also downcomer velocity of bubbles was slower than circulation velocity of liquid and riser velocity of bubbles was fast than circulation velocity. The bubble-size-distribution of bubbles in the deep shaft was the logarithmic probability distribution. The number of bubbles in the deep shaft was decreased in accordance with depth and the number of bubbles in the downcomer is more than the bubbles in the riser.

• Journal of Wetlands Research
• /
• v.25 no.3
• /
• pp.176-183
• /
• 2023

The aim of this paper is to understand the blade number effect on vortex turbine performance in the cylindrical vortex chamber below the free water surface. Using the same blade profile, the performance of gravitational vortex turbine is tested each with 2, 3, 4, 5 and 6 blades installed at the relative vortex height (y/h_v) ranging from 0.065 to 0.417. The obtained results indicate that the rotation, voltage, current and power increase in the relative vortex height of 0.065 and 0.111 when increasing the number of blades at flow velocity of less than 0.7 m/s. The average power of the 5-blade turbine is more than others. The performance of the 4-blade turbine with a 130 mm diameter installed near the orifice is higher than that of the same number of blades with a 220 mm diameter in the vortex chamber.

• Journal of the Korean Society for Marine Environment & Energy
• /
• v.17 no.3
• /
• pp.182-188
• /
• 2014

In an oscillating water column (OWC)-type wave energy conversion system, the performance of the OWC chamber depends on the chamber shape, as well as the incident wave direction and pressure drop produced by the turbine. Although the previous studies on OWC chambers have focused on wave absorbing performance in ideal operating conditions, incident waves do not always arrive normally to the OWC chamber in real sea conditions, especially in fixed devices. The present study deals with experiments and numerical calculations to investigate the effects of wave direction on the performance of the OWC chamber. The experiments were carried out in a three-dimensional wave basin for five different wave directions, including the effect of turbine using the corresponding orifice. The wave elevation inside the chamber was measured at the center point under various incident wave conditions. The numerical study was conducted by using a numerical wave tank-based volume-of-fluid model to compare the results with experimental data and to reveal the detailed flows around the chamber.

• Journal of Aerospace System Engineering
• /
• v.16 no.5
• /
• pp.17-25
• /
• 2022

The pintle injector has many advantages in the key characteristics of a liquid rocket engine, such as combustion stability, combustion efficiency, and wide range of comprehensive thrust control, design and manufacture, and test fired under supercritical conditions. The pintle injector is manufactured with a rectangular, single-row orifice for thrust control and production considerations. In order to verify the combustion performance of the pintle injector and its potential as a commercial injector, the combustion characteristics were analyzed by varying the TMR (Total Momentum Ratio) and BF (Blockage Factor). The result of the hot firing test showed that the heat flux increased as TMR increased, and it confirmed that the characteristic velocity efficiency was more affected by BF than TMR. Suppose a single-row pintle injector with efficiency characteristics insensitive to changes in TMR can achieve high efficiency at low fuel differential pressure conditions. In that case, the variable pintle injector's design flexibility can be increase.