Interior Ballistics of a Combustion Chamber Discharging a Weight

Dan Michaels
Work toward a Ph.D. degree under the supervision of Prof. Alon Gany
Faculty of Aerospace Engineering
Technion – Israel Institute of Technology

A unique concept for short action motors, based on a rocket-type combustion chamber discharging a weight through an exhaust tube will be presented and investigated. Such short action motors may be beneficial for spacecraft and missile trajectory correction, applying mini-thrusters of this kind as well as for separating large space bodies such as missiles/launcher stages, satellites, etc. Calculations with granular double-base propellant and a solid ejected weight reveal that a specific impulse based on the propellant mass of well above 400 seconds can be obtained for small ejected weights (compared to a typical value of 250 s for solid rockets). Space body separation using this technique can result in specific impulse exceeding 10,000 seconds. An experimental thruster was built in order to demonstrate the new idea and validate the model. The thruster impulse was measured both directly with a load cell and indirectly by using a pressure transducer and high speed photography of the weight as it exits the tube, with both ways producing very similar total impulse measurement. The good correspondence between the computations and the measured data validates the model as a useful tool for studying and designing such a thruster.
Replacing the weight with a traveling propellant charge appears to be very beneficial, as it can provide higher total impulse and the possibly of eliminating the ejection of a solid inert weight. A system comprising a granular solid propellant and a traveling charge composed of a unique very high burn rate propellant has been considered. The results demonstrate the benefits of using the traveling charge and reveal important design consideration.

The talk will be given in English

Wed, 16-07-2014, 16:30 (Gathering at 16:00)

Classroom 165, ground floor, Library, Aerospace Eng.

Light refreshments will be served before the lecture

Interior Ballistics of a Combustion Chamber Discharging a Weight