• Journal of the Korean Society of Propulsion Engineers
• /
• v.18 no.1
• /
• pp.58-64
• /
• 2014

Hydraulic dual chamber, as the simulator for a dual pulse rocket motor, was tested by a high pressure device with various orifice-hole size being applied. Pressure difference occurs between 1st chamber and 2nd chamber depending on area ratio of the orifice to nozzle throat. Studying a design configuration of the orifice is essential to the motor development because pressure difference severely affects the rocket motor performance. It is noticed in this study that energy dissipation is caused by the vortex flow originating from the orifice as the 2nd chamber is operated. The flow field is simulated by a commercial computational fluid dynamics program, ANSYS FLUENT V14.5.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2013.10a
• /
• pp.815-824
• /
• 2013

Pneumatic exciters can be good replacements of electrodynamic, piezoelectric and hydraulic exciters owing to simple structure and large exciting force. One problem to be solved is a slow response caused by compressibility of air. Desirable frequency response characteristics of exciter are constant magnitude and zero degree phase, because users want no time delay between input signal and output force. For this reason, frequency range of pneumatic exciters is limited about 0~1 Hz. Therefore, expansion of frequency range is an important issue when designing the pneumatic exciter. In this paper, the pneumatic exciter which has same structure with active pneumatic isolator is dealt with. The dynamic characteristics are presented, and its limitation of expanding frequency range is shown based on analytical studies. Then the pneumatic exciter with dual-chamber is suggested to overcome this problem. Based on simulation study, a design method is presented.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.23 no.10
• /
• pp.909-919
• /
• 2013

Pneumatic exciters can be good replacements of electrodynamic, piezoelectric and hydraulic exciters owing to simple structure and large exciting force. One problem to be solved is a slow response caused by compressibility of air. Desirable frequency response characteristics of exciter are constant magnitude and zero degree phase, because users want no time delay between input signal and output force. For this reason, frequency range of pneumatic exciters is limited about 0~1 Hz. Therefore, expansion of frequency range is an important issue when designing the pneumatic exciter. In this paper, the pneumatic exciter which has same structure with active pneumatic isolator is dealt with. The dynamic characteristics are presented, and its limitation of expanding frequency range is shown based on analytical studies. Then the pneumatic exciter with dual-chamber is suggested to overcome this problem. Based on simulation study, a design method is presented.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2007.05a
• /
• pp.1112-1118
• /
• 2007

This paper investigates the performance of an electromagnetic type active control engine mount (ACM) recently developed in the laboratory. The ACM employs the basic structure of the conventional hydraulic engine mount of which upper chamber is connected to a dual magnet electromagnetic actuator. The actuator, that essentially replaces the existing decoupler of the conventional passive hydraulic engine mount, actively controls the upper chamber pressure. Using the linearized ACM model incorporated with the actuator dynamics, we suggest an optimal design of ACM, maximizing the actuator efficiency as well as the vibration isolation efficiency.

• Journal of the Korea Institute of Military Science and Technology
• /
• v.6 no.4
• /
• pp.113-123
• /
• 2003

Both numerical analysis and experiment of cold and hot tests were performed to obtain basic design data for the swirl coaxial type Injector and to predict the combustion performance. Mass distribution, mixing distribution, mixing efficiency, characteristic velocity efficiency were measured by the cold tests and numerical analysis using the commercial thermo-hydraulic program. Test and analysis variables were recess, pressure drop, velocity ratio, mixing spray, mixture ratio. Hot tests were performed for the Uni-element injector to compare the performance with the cold test results, and, hot tests for Multi-element injector were performed to compare the performance with Uni-element injector. Designed thrust of the Uni-element injector liquid rocket was 35kgf at sea level and combustion chamber pressure, 20bar. Kerosene and Lox were used as a propellant.