Improvement of regression rate and combustion efficiency of high density polyethylene fuel and paraffin fuel of hybrid rockets with multi-section swirl injection method

In order to improve fuel regression rate of hybrid rockets, a new method with multisection swirl injection is proposed. The new method is to introduce swirling flow through multi-section swirl injector ports, which are placed at several locations along the fuel grain. The key point of the method is to generate swirling flow in the cavity of the fuel grain and provide oxidizer at several cross-sections. In the present study four injector ports are located at four cross-sections along the axis of the fuel grain. At each cross-section of the fuel grain four injector ports are located at every 90 degrees with deflected angle where injected oxidizer causes swirl at a cross-section in the fuel grain cavity. The method is applied for high density polyethylene fuel and paraffin fuel (FT-0070) with pressurized gaseous oxygen. The results show the average regression rate of the proposed method is about 2 - 3 times with high density polyethylene fuel and 10 times with paraffin fuel compared with that of the conventional no-swirl injection method.