Mixing Determination for Solid Rocket Fuel Production by Peristaltic Mixing Pump Using Packing Method

For space rockets, a rotating mixer is used to produce solid fuel. However, mixing with the rotary mixer is subject to high shear forces that limit the equipment drive. In a previous study, the authors developed a new production method using a pneumatically driven peristaltic mixing pump that simulates the intestine and a sensing system with pressure and flow rate sensors. Solid rocket fuel was successfully produced by a small pump unit. In this study, mixing experiments of solid propellant consisting of several types of powders, including metal powder and highly viscous fluids were conducted using a pump unit with a volume size eight times larger than that used in the previous study. In this experiment, mixing was performed with the materials packed in a plastic bag to increase efficiency. This reduces the contact area between the rubber tube and the contents of the device. Because only part of the mixing process is reflected in the behavior of the device, it is difficult to see differences in the sensor values, and it is unknown whether existing methods can be applied. The results of the experiment showed that the existing sensing system could be used to confirm the differences in characteristics due to the mixing process based on the time series data of air pressure and flow rate. By using Gaussian mixture model, which is a type of clustering, the mixing state was roughly binary discrimination from the acquired sensor values. This suggests that it is possible to estimate the mixing degree in large pumps using existing systems.