• 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.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2005.11a
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• pp.487-490
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• 2005

The thrust Control in Solid Propellant Rocket is incomparably limited than that in Liquid Propellant Rocket. Because it is fixed that section to relate a combustion, that is a natural result. The control of a thrust directions in a Solid Propellant Rocket is not efficient for the purpose of a Solid Propellant Rocket. But it is a problem to solve that a weight on board should increase through the maximization of the thrust in a Solid Propellant Rocket.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2003.05a
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• pp.23-26
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• 2003

Recently, the thrust vector control using a secondary flow injection which is accomplished by injecting a secondary flow into the supersonic exhaust flow through hole in the wall of the propulsion nozzle has been attention in the applications of the rocket propulsion system. In the present study, 3-dimensional compressible, Navier-Stokes equation to understand the SITVC(Secondary Injection Thrust Vector Control) flow field. The computational results are validated with previous experimental data available. The computational results are visualized detailed structure of shock wave induced by secondary flow and deflected supersonic jets.

• Journal of the Korean Society of Propulsion Engineers
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• v.3 no.1
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• pp.1-8
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• 1999

In the present paper an attempt has been made to simulate the secondary injection-primary flow interaction in the conical rocket nozzle and to derive the performance of secondary injection thrust vector control(SITVC) system. Complex three-dimensional flowfield induced by the secondary injection is numerically analyzed by solving unsteady three-dimensional Euler equation with Beam and Warming's implicit approximate factorization method. Emphasized in the present study is the effect of secondary injection such as secondary mass flow rates and the momentum of secondary/primary nozzle flow mass rates upon the gross system performance parameters such as thrust ratio, specific impulse ratio and deflection angle. The results obtained in terms of system performance parameters show that lower secondary mass flow rate is advantageous for to reduce secondary specific impulse loss. It is further found that the nozzle with secondary jet injected downstream and interacting with fast primary flow is preferable for efficient and stable SITVC over the wide range of use with the penalty of side specific impulse loss.

• Journal of the Korean Society of Propulsion Engineers
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• v.5 no.1
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• pp.18-25
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• 2001

The results of systematic numerical experiments of secondary gas injection thrust vector control are presented. The effects of secondary injection system such as injection location and nozzle divergent cone angle onto the overall performance parameters such as thrust ratio, specific impulse ratio and axial thrust augmentation, are investigated. Complex nozzle exhaust flows induced by the secondary jet penetration is numerically analyzed by solving unsteady three-dimensional Reynolds-averaged Navier-Stokes equations with Baldwin-Lomax turbulence model for closure. Numerical simulations compared with the experiments of secondary air injection into the rocket nozzle of $9.6^{\cire}$ divergent half angle showed good agreement. The results obtained in terms of overall performance parameters showed that locating the secondary injection orifice further downstream of primary nozzle ensures the prevention of occurrence of reflected shock wave, therefore is suitable for efficient and stable thrust vectoring over a wide range of use.

• 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.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.11a
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• pp.213-217
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• 2011

Unsteady numerical simulations of pintle nozzles were implemented for solid rocket thrust vector control. The variation of pintle location was considered using unsteady numerical techniques, and dynamic characteristics of various pintle models were investigated. In order to consider the variation of the pintle location, a moving mesh method was applied. The effects of shape and location of the pintle nozzle have been analytically investigated. And the results were compared with numerical results. The chamber pressure, mass flow and thrust are analyzed to take account dynamic characteristics of pintle performance.

• The KSFM Journal of Fluid Machinery
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• v.18 no.5
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• pp.49-53
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• 2015

Thrust vector control is the method which generates the side force and roll moment by controlling exhausted gas directly in a rocket nozzle. TVC is classified by mechanical and fluid dynamic methods. Mechanical methods can change the flow direction by several objects installed in a rocket nozzle exhaust such as tapered ramp tabs and jet vane. Fluid dynamic methods control the flight direction with the injection of secondary gaseous flows into the rocket nozzle. The tapered ramp tabs of mechanical methods are used in this paper. They installed at the rear in the rocket nozzle could be freely moved along axial and radial direction on the mounting ring to provide the mass flow rate which is injected from the rocket nozzle. TVC of the tapered ramp tabs has the potential to produce both large axial thrust and high lateral force. We have conducted the experimental research and flow analysis of ramp tabs to show the performance and the structural integrity of the TVC. The experiments are carried out with the supersonic cold flow system and the schlieren graph. This paper provides to analyze the location of normal shock wave and distribution of surface pressure on the region enclosed by the tapered ramp tabs.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.33 no.1
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• pp.85-92
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• 2005

The motion of flexseal bearing for movable nozzle has inherent nonlinear characteristics due to floating rotational center and compression by combustion pressure of solid motor. To perform precise attitude control in spite of these characteristics, the TVC actuation system requires counter potentiometer as an extra position feedback sensor of movable nozzle to form a compensated control loop. The prototype TVC actuation system, test equipments and compensated controller are newly designed, manufactured and tested in consideration of counter potentiometer. On the basis of integration test, the inherent characteristics of movable nozzle and control characteristics of its TVC actuation system are analyzed and summarized in this paper.

• International Journal of Fluid Machinery and Systems
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• v.9 no.4
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• pp.354-361
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• 2016

This study aims to identify aerodynamic characteristics of the ramp tab, a mechanical deflector, by conducting a non-combustive experiment using compressed air and supersonic flow test equipment. With the ramp tabs installed symmetrically and asymmetrically on the outlet of the supersonic nozzle, the structure of the flow field, the thrust spoilage, the thrust deviation angle, and the lift/drag coefficients were derived and analyzed. The results show that the asymmetrically-installed ramp tabs are advantageous relative to the symmetrically-installed tabs in terms of the performance of thrust vector control, thrust deviation angle, and lift coefficient.