This paper presents research related to the tubular combustion chamber of an expendable turbojet. Although annular combustors are dominant at present, tubular combustors are still attractive because they are simpler to produce and require lower amounts of air flow for testing. The objective of this research was to assess the combustor’s primary zone configuration, and four configurations were tested to obtain experimental answers for use in future work. The configuration of the combustion chamber is a simple and classic design in line with its expendable purpose. The test methodology was to perform initial testing of the primary and secondary zones under atmospheric conditions using the four configurations, and then to subsequently complete the combustor using the best configuration. The complete combustor was then tested under both atmospheric conditions and working conditions. The results showed that the stability margin was wide enough to cover the combustor’s entire working area. The measured efficiency and pressure drop were in very good agreement with the corresponding designed values. The design and testing methodology proposed here could be used for similar scientific and engineering research applications.

The operation of gas generators brings relatively high thermo-mechanical loads on the gas generator structure. The objective of this article is to determine the operating conditions, in terms of mechanical loads at extremely high temperatures in very limited and narrow space, of a multifunctional bulkhead for application on specific kinds of gas generators with back-to-back rotor concept. The paper contains numerical analysis and experimental investigation for determining the loads and behavior of the structure. Numerical analysis indicates that there is significant influence of the Tesla turbine effect on flow parameters. Also, uneven pressure distribution and significant thermal loads are identified. With experimental investigation and subsequent exploitation tests, it was concluded that the presented methodology identifies the operating conditions, truthfully simulates the bulkhead stress state and deformations and that the presented design solution satisfied all demands. Regarding results obtained by these numerical simulations, the innovative design solution for the multifunctional bulkhead was proposed.

Original scientific paper This study proposes an innovative test stand design to accurately measure rocket motor thrust vector during its operation. Test stand design is clearly presented as well as procedure and mathematical model for its calibration. A method of processing data obtained from the experiments and the results of the jet tab system for thrust vector control are presented in detail. Experiments have shown that the test stand is highly functional and the results obtained have excellent repeatability and matching with the results of the other authors who have used different construction test stands for measurement of the same or a similar mechanism for thrust vector control. Keywords: jet tab; rocket motor; test stand; thrust vector control Novi ispitni stol sa šest stupnjeva slobode za ispitivanje upravljanja vektorom potiskaIzvorni znastveni rad U ovom radu se predlaže inovativnu konstrukciju ispitnog stola za precizno mjerenje vektora potiska raketnog motora tijekom njegovog rada. Jasno je izložena konstrukcija ispitnog stola kao i procedure te matematički model za kalibraciju ispitnog stola. Metoda obrade podataka dobivenih ispitivanjem kao i rezultati ispitivanja "jet tab" sustava za upravljanje vektorom potiska detaljno su prezentirani. Eksperimenti su pokazali da je ispitni stol iznimno funkcionalan, a da dobineni rezultati imaju odličnu ponovljivost i poklapanje s rezultatima autora koji su koristili ispitne stolove drugačije konstrukcije za mjerenje istog ili sličnog mehanizma za upravljanje vektorom potiska.

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