| A Study on the Pressure Increase due to the Foam Left in the Radial Slot of Propellant Grain |
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Jong-Yul Kim, Gyoo-Dong Jung, Jun-Seo Yang |
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Agency for Defense Development |
| 추진제 그레인 래디얼 슬롯내의 폼 코어에 의한 압력증가 해석 |
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김종율, 정규동, 양준서 |
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국방과학연구소 |
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| Abstract |
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The radial slot configuration in the solid propellant grain is usually fabricated by the polyurethane foam slot former The foam cannot be easily removed from the solid propellant, some can remain in the slot. Analogue solid propellant rocket motors using polyurethane foam to shape the slot are static fired with the foam former still in place in the slot. The pressure increases at the slot part are measured and there are indications of the propellant cracks at the insulations above the slot. The pressure increase is produced at the beginning of the burning sequence as the foam will hinder the combustion gas of the burning propellant from flowing into the central bore. The pressure increase up to about 300psi is predicted for the motor tested and this pressure increase depends on the gap between the propellant and foam surfaces and remaining foam volume. This amount of pressure increase inside of the slot is estimated to cause the propellant crack. To prevent this pressure increase, minimizing the foam remainder in the slot and making sufficient chamfering at the comer of the slot entrance are suggested. |
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