Design and testing of injectors manufactured using additive technologies for a low-thrust liquid rocket engine

Modern liquid rocket engines of low thrust (LRELT) represent complex engineering structures, which are subject to very high requirements in terms of efficiency, reliability, and cost-effectiveness. To confirm the characteristics of the developed designs, a comprehensive set of tests for prototype samples is required, allowing their operability to be verified under conditions close to real-life operation. As part of this work, a thermodynamic calculation of the LRELT chamber for fuel components such as liquid kerosene and gaseous oxygen was conducted. The injector calculation method used in this work is based on the application of similarity criteria. This allows the transition from small-scale injectors to those suitable for full-scale testing, including stand tests using the “hydroflush” method. For testing, a specialized test rig was created, allowing the testing of injectors manufactured using modern additive technologies, such as 3D printing from polymer materials. This not only reduces the cost of creating prototypes but also accelerates the testing process. The injector tests on the stand play a crucial role in verifying their operability. This testing method allows studying the behavior of injectors in conditions as close to operational as possible. In this study, injectors manufactured using additive technologies from polymer plastic were used. The use of such materials in the early stages of testing helped to reduce costs and time resources for producing prototype samples. During the tests, the injectors were subjected to liquid at a specified pressure differential, which allowed their operability and fuel distribution uniformity to be assessed. The results of the tests demonstrated a high degree of correlation between theoretical calculations and actual data. The injectors showed stable operation corresponding to the calculated characteristics, and also proved their suitability for further development stages. The use of additive technologies in the manufacturing of the injectors confirmed its effectiveness, allowing the prototype production cycle to be shortened and costs reduced. Moreover, the “hydroflush” method proved to be a reliable means of verifying and validating the working characteristics of the injectors, which is an important step toward their implementation in real-world operations. Thus, the proposed methodology, which includes the use of similarity criteria and additive technologies, significantly simplifies the process of development and testing, improves accuracy, and brings the results closer to real operating conditions. This is especially important for increasing the reliability and quality of final products used in rocket and space technology, contributing to a reduction in operational risks.