Experimental and Numerical Investigation of N2O Flow Feeding System in a Hybrid Rocket

• Main Authors: Chuang, Kang-Ming, 莊康旻
• Other Authors: Wu, Jong-Shinn
• Format: Others
• Language: en_US
• Published: 2012
• Online Access: http://ndltd.ncl.edu.tw/handle/56628900210202698679

碩士 === 國立交通大學 === 機械工程學系 === 100 === Hybrid rocket propulsion has attracted much attention recently mainly because of its capability of thrust profiling, in addition to its safe and green operation. To realize thrust control, the easiest way is to accurately control the flow rate of oxidizer flowing into the combustion chamber. In this thesis, a venturi flow meter calibration/measurement system for pressurized nitrous oxide or carbon dioxide is developed and validated by comparing between experiments and flow simulations using real-fluid HMBS model. An incompressible Bernoulli type empirical correlation that links between pressure difference (inlet and throat) and mass flow rate is also proposed with an empirical coefficient. This venturi flow meter calibration/measurement system for nitrous oxide includes a nitrogen pressurized source tank with adjustable pressure (63-85 bars), a venturi flow tube and an orifice (7 mm in diameter) for controlling the back pressure in the downstream of flow meter. CO2 is used as the working gas in this thesis instead of N2O because of their similarity in thermodynamic behavior and also large cost saving. Three different venturi flow tubes, including 10, 28 and 28 mm in inlet diameter with 8, 16 and 20 mm in throat diameter, respectively, were designed to cover different ranges of mass flow rates, including 1~2, 3~8, 6~12 kg/s, respectively. Pressure transducers and themocouples were used to measure instantaneous pressure and temperature, respectively, wherever is necessary. A load cell is used to measure the instantaneous weight of the pressurized tank during experiment that can be used to deduce the instantaneous mass flow rate. Results show that the simulations agree very well with the measurements performed in the current study. An empirical correlation based on the incompressible Bernoulli type equation is proposed with velocity coefficients of 0.96, 0.97, and 0.91, respectively, for the three ranges of flow rates as mentioned in the above. Recommendations for future work are also outlined at the end of the thesis.