• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2005.11a
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• pp.40-45
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• 2005

Techniques used for throcket motors are mainly classified as fixed nozzles with mechanical exhaust jet interferences on the expansion region (such as jet tabs and jet vanes) and movable nozzles(such as ball&socket md flexible seal). Using the numerical analysis and the cold-flow test, this paper evaluates the performance of supersonic nozzle for asymmetric entrance shape at tilted position of ball&socket nozzle. Numerical results show that the asymmetric effects in the flow fields are gradually diminished up to the nozzle throat and are not noticeable downstream of the nozzle throat. Although the calculated thrust and the lateral force are less than those of cold-flow test, two results show a flirty good agreement.

• Journal of the Korean Society of Propulsion Engineers
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• v.10 no.2
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• pp.46-52
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• 2006

Techniques used for thrust vector control in rocket motors are mainly classified nozzles installed mechanical interference on the expansive region of nozzle(such as jet tabs and jet vanes) and movable nozzles(such as ball&socket and flexible seal). Using the numerical analysis and cold-flow test, this paper evaluates the performance of supersonic nozzle with asymmetric entrance shape when the test nozzle, especially ball&socket, is tilted. Numerical result shows that the effect of the asymmetric entrance shape on the flow field is suddenly diminished at the nozzle throat and downstream is mostly free from the effect of asymmetric entrance shape. Although the calculated thrust and lateral force are less than those of cold-flow test, two results show a fairly good agreement. But the cold-flow test results indicate the effective angles calculated from measured forces are not agreement with the geometric angles.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.37 no.9
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• pp.899-905
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• 2009

Most supersonic-flow test facility has axisymmetric nozzles or two-dimensional symmetric nozzles. Compared to these nozzles, a two-dimensional asymmetric nozzle has advantages of reducing low cost for various Mach number testing and undesirable flow structure such as shock wave reflection because the nozzle part can be directly connected to the test section part in this type of nozzle. The two-dimensional asymmetric nozzle, which was Mach number 2, was designed for supersonic combustion experiment. And it was verified with the numerical analysis and visualization of Mach wave. This study suggested the practical method for design and verification of supersonic two dimensional asymmetric nozzles.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.04a
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• pp.61-65
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• 2011

In this paper, the nozzle design with asymmetric configuration using the optimal method is used in order to improve the under- and over-expansion problem of the flow at the supersonic turbine nozzle. For the design of nozzle contour, 8 design variables are selected and the total-to-static efficiency from the nozzle inlet to the wake outlet is considered as the objective function to be maximized. The Fluent6.3 and the iSIGHT-FD program are used for calculation of nozzle flow and design optimization respectively. RBF(Radial Basis Function) method is chosen for approximate optimization algorithm. It is shown that the static efficiency of improved nozzle design increases 1.35% and loss coefficient decreases 19.85% as compared to baseline design.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2012.05a
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• pp.110-116
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• 2012

To analyze flow characteristics and performance of the side jet thruster with 4 shutters and rectangular nozzles, a 3-D simulation has been implemented. Numerical calculations for three rotation anlgles of the shutter, have been conducted. Internal recirculation in a chamber and asymmetric flow structure in a nozzle were observed. In addition, the more shutter rotated, the more asymmetries of flow increased, and this phenomena resulted in thrust bias. The degrees of thrust bias and thrust performance with the rotation angles of the shutter were predicted and comparisons with theoretical thrust were made.

• Journal of the Korean Society of Propulsion Engineers
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• v.17 no.2
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• pp.63-70
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• 2013

To analyze flow characteristics of the side jet thruster with 4 shutters and rectangular nozzles, a 3-D simulation has been implemented. Numerical calculations for two rotation angles of the shutter, have been conducted. Internal recirculation in a chamber and asymmetric flow structure in a nozzle were observed. In addition, the more shutter rotated, the more asymmetries of flow increased, and this phenomena resulted in thrust bias. The degrees of thrust bias and thrust performance with the rotation angles of the shutter were predicted and compared with theoretical thrust.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2017.05a
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• pp.383-387
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• 2017

A three dimensional numerical analysis has been conducted to analyze the effects of a pipe angle, connecting a combustion chamber and a pintle nozzle, and pintle position on pintle nozzle performance. The compressibility correction of $k-{\omega}$ SST turbulent model was implemented to precisely predict the characteristics of complex flow structures inside a supersonic pintle nozzle. Due to an 3-D asymmetric pintle nozzle configuration, complex helical flow streamlines and large flow separations were observed, which resulting in significant nozzle performance losses. As the angle of connection-tube decreases, the coefficient of performance increases and Since the flow structures are evidently changed to the pintle stroke position, the performance characteristics was analyzed.

• Journal of ILASS-Korea
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• v.4 no.4
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• pp.38-45
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• 1999

The near field structure of round turbulent jets with initially asymmetric velocity distribution is investigated experimentally. Experiments were carried out using a constant temperature hot-wire anemometry system to measure streamwise velocity in the jets. The measurements were undertaken across the jet at various streamwise stations in a range starting from the jet exit plane and up to a downstream location of twelve diameters. The experimental results include the distribution of mean and instantaneous velocities, vorticity field, turbulence intensity, and the Reynolds shear stress. The asymmetry of the jet exit plane was obtained by using circular cross-section pipes with a bend at the upstream of the exit. Three pipes were used for this study: A straight pipe, 90 and 160 degree-bended pipes. Therefore, at the upstream of the pipe exit, the secondary flow through the bend and the mean streamwise velocity distribution could be controlled by changing the curvature of pipes.

• Journal of the Korean Society of Propulsion Engineers
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• v.15 no.2
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• pp.29-35
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• 2011

The behaviors of combustion-induced internal flows of SRM equipped with fin-slot grain and submerged nozzle are very complex and diverse. Cold air-flow tests for 2D and 3D scale models of SRM have been done in order to specify the visualization method to analyze particular internal flow patterns such as roll-torque inducing flow. Swirl flow induced by asymmetric vortical tubes also has been visualized through employing various light source and recording directions.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2010.11a
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• pp.181-185
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• 2010

The behavior of combustion-induced internal flow of SRM equipped with fin-slot grain and submerged nozzle is very complex and diverse. Cold air-flow test for 2D and 3D scale models of SRM has been done in order to specify the visualization method to analyze particular internal flow patterns such as roll-torque inducing flow. Swirl flow induced by asymmetric vortical tube also has been visualized through employing various light source and recording directions.