• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2007.11a
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• pp.215-218
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• 2007

Internal Ballistic modeling and performance prediction for solid propellant micro thruster was performed with heat loss to the chamber wall as an important factor of miniaturization. Simple l-D end-burner type thruster and general HTPB-AP type composite propellant were selected for computation model. The results showed that the performance loss with the heat loss to the surroundings becomes larger as the surface-to-volume ratio is increased. In this case, the total impulse was reduced about 3% of the case in adiabatic condition.

• Journal of the Korean Society of Propulsion Engineers
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• v.24 no.3
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• pp.47-58
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• 2020

In this study, a thrust modulation through oxidizer mass flow rate control and internal ballistic analysis based on Whitmore and Chandlers' models was conducted on a blow-down hybrid rocket using nitrous oxide. The tank pressure prediction considering mass flow rate control of the self-pressuring oxidizer was conducted, and the results showed good agreements with experimental results. In order to verify the internal ballistic analysis, a ground combustion test using a 500 N class hybrid rocket was conducted, and it was confirmed that the experimental results and the analytical results were quite consistent in the chamber pressure and thrust, thereby, a modeling technique capable of predicting the thrust modulation performance is proposed.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.36 no.1
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• pp.79-85
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• 2008

Generally Solid Rocket Motor(SRM) has advantages like this - safety, simplicity and flexibility in design and manufacturing process. However, once propellant grain shape and nozzle throat area are determined, modification of thrust magnitude is nearly impossible. Recently, methods for controlling the thrust magnitude of SRM are vigorously developed. This paper predicts internal ballistic performance variation, especially thrust of SRM by means of Linear Approximation according as chamber pressure or nozzle throat area is changed. The results predicted by the proposed method are good agreement with the those of exclusive Ballistic Performance Prediction Program(SPP).

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2008.03a
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• pp.247-254
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• 2008

The primary objective of this research is to develop an efficient design and optimization methodology for SRM Wagon Wheel Grain and to develop of software for practical designing and optimization of Wagon Wheel grains. This work will provide a design process reference guide for engineers in the field of Solid Rocket Propulsion. Using these proposed design methods, SRM Wagon Wheel grains can be designed for various geometries, their optimal solutions can be found and best possible configuration be attained thereby ensuring finest design in least possible iterations & time. The main focus is to improve computational efficiency at various levels of the design work. These have been achieved by the following way. a. Evaluation of system requirements and design objectives. b. Development of Geometric Model of Wagon Wheel grain configuration. c. Internal ballistic performance predictions. d. Preliminary designing of the Wagon Wheel grain configuration involving various independent geometric variables. e. Optimization of the grain configuration using Sequential Quadratic Programming f. In depth analysis of the optimal results considering affects of various geometric variables on ballistic parameters and analysis of performance prediction outputs have been performed g. Development of software for design and optimization of Wagon Wheel Grain. By using these proposed design methods, SRM Wagon Wheel grains can be designed by using geometric model, their optimal solutions can be found and best possible configuration be attained thereby ensuring finest design.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.11a
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• pp.50-54
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• 2011

This paper presents a two-phase model for hybrid rocket internal ballistics design using $N_2O$ as oxidizer The two-phase model results are compared with data obtained from static firing test. Two-phase model is suitable for blow-down type with saturated compressible fluid as $N_2O$, presented the result by Part 1. HDPE as Fuel, and $N_2O$ as oxidizer were used during the static firing test. The combustor were designed for an average thrust of 30 kgf where oxidizer tank pressure in set to 50 bar. The numerical results of internal ballistic showed good agreements with static firing test results where thrust, oxidizer tank pressure and chamber pressure are compared.

• Journal of the Korean Society of Propulsion Engineers
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• v.21 no.3
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• pp.61-67
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• 2017

In this study, Burning Area Analysis Program (BAAP) was developed by using VOF method to estimate the burning area of 3D shaped grain. The parametric study of mesh size, burning rate and time interval for numerical calculation was conducted. The result of BAAP is compared with the one from commercial 3D modeling software. Also the internal ballistic analysis was performed using the result of BAAP. In order to estimate the burning area and internal pressure with time, Chemical Equilibrium Analysis (CEA) was conducted with a composition of reduced smoke propellant. As a result, the web-averaged pressure was 5.34 MPa which is similar to the published research result.

• Journal of the Korean Society of Propulsion Engineers
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• v.11 no.2
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• pp.79-85
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• 2007

An internal ballistic model to predict the performance of a Polyethylene-GOX (PE-GOX) hybrid motor was proposed and evaluated. A theoretical treatment of the model was followed by detail discussion of each of the factors affecting the overall performance. The present model consists of the governing equations by considering the unsteady burn-back rate of the fuel grain and on-off response characteristics of a oxygen-supply valve. The numerical results using the 4th order Runge-Kutta scheme with temporal physicochemical properties showed good agreements with test results and the global effects of the performance parameters, such as the burning area of the fuel grain, O/F ratio, and etc., on the performance of the motor were analyzed.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2008.03a
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• pp.226-234
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• 2008

Grain design has always been a vital and integral part of Solid Rocket Motor(SRM) design. Basing on the design objectives set by the system designer, the SRM designer has many options available for selecting the Grain configuration. Many of the available configurations may fulfill the required parameters of volumetric loading fraction, web fraction & Length to diameter ratios and produce internal ballistic results that may be in accordance to the design objectives. However, for any given set of design objectives, it is deemed necessary that best possible configuration be selected, designed and optimized. Hence optimal results of all applicable configurations are vital to be attained in order to compare and finalize the design that will produce most efficient performance. Generally the engineers pay attention and have skills on a specific grain configuration. The designing methodologies and computer codes available usually focus on single grain configuration may it be Star, Wagon Wheel or slotted tube. Hardly one can find a software or a design methodology where all such configurations can be worked on jointly and not only adequate designs be found but optimal solutions reached by applying an optimization method to find final design best suited for any design objective. In the present work design requirements have been set, grain configurations have been selected and their designing has been conducted. The internal ballistic parameters have been calculated and after finding the preliminary design solutions, the optimal solutions have been found. In doing so, software has been developed comprising of computer programs for designing the 2D grains including Star, Wagon Wheel and Slotted Tube configurations. The optimization toolbox of Matlab Fmincon has been used for getting optimal solutions. The affects of all the independent geometric design variables on the optimized solutions have been analyzed. Based on results attained from Optimization Method, an in depth comparison of Grain Configurations and analysis of performance prediction outputs have been conducted to come to conclusion as to which grain configuration is ideal for the current design requirement under study.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.04a
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• pp.356-359
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• 2011

In this study, applicable to Sounding Rocket about the development of high-performance propellant was studied. Sounding Rocket requires generally multistage rocket system for atmospheric research. This study describes the development of two types solid propellant compositions which are based on HTPB/AP for the two-stage rocket. CEA code of NASA and internal ballistic analysis were used for confirming the theoretical performance of designed propellants. The strand burner and JANNAF tensile test was used to measure ballistic and mechanical properties of designed propellants. Finally, static fired test of standard motors was performed to prove the possibility of development.

• Journal of the Korean Society of Propulsion Engineers
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• v.18 no.5
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• pp.19-28
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• 2014

Firing test of solid rocket motor with pintle-technology carried out and the measured pressure-time curve was compared with the values predicted by the internal ballistic and performance analysis. Without baffle, the measured combustion chamber pressure was similar with the predicted pressure at the beginning of combustion, but gradual increase in pressure, which was unexpected with the end-burning grain of which burning area is constant, was observed. A baffle was inserted to make uniform flow over the pintle. Unlike the thruster without baffle, the measured combustion chamber pressure was 1.4 times higher than the predicted value. Through the CFD simulation, 10% of total pressure loss of the flow was observed from combustion chamber to nozzle throat when the baffle was inserted. The measured pressure with baffle was predicted well by considering the total pressure loss in the internal ballistic modelling and performance analysis.