Temperature Stratification in a Self-Pressurized Nitrous Oxide Tank

Self-pressurized nitrous oxide feed systems have gained the attention of many rocket designers because of their overall simplicity and low mass. A study of temperature stratification in tanks during evacuation is important for the modeling of a self-pressurized nitrous oxide system. In this study, an experimental apparatus has been constructed with a series of temperature sensors equally distributed in the tank’s axial direction to measure stratification and with a set of load cells to measure the nitrous oxide mass flow rate. The response time of the temperature sensor in water is also measured and is evaluated in the test. The temperature distribution in the tank is measured during the filling and evacuation processes. It is observed that temperature stratification in the liquid region is so small that it can be modeled with a lumped parameter node. However, the stratification will always occur in the vapor region, making it insufficient to be modeled with a lumped parameter node. The saturation temperature based on the pressure in the tank is marginally higher than that in the liquid.