Review of ejector nozzles.Part 1 – Thrust augmenting ejector nozzles

The subject of this article is ejector nozzles, which are intended for the thrust augmentation of jet engines. The goal of this study is to analyze the contradictions between technical requirements and the requirements of manufacturability and price, between the required high characteristics of ejectors and compactness, and between the conflicting goals of achieving a high mixing rate with low losses of the total pressure of the primary flow within a short total length. Moreover, this study aims to identify methods for rationally reducing these contradictions by using effective mixers of the primary and secondary flows. The tasks to be solved are: development of a classification, revealing the advantages and drawbacks of thrust augmenting ejector nozzles, and analysis of the main directions in ejector nozzle research (theoretical research based on simplified models, experimental research using improved models, and research using computational fluid dynamics models). The following methods were used: search of corresponding information sources on the Internet and analysis based on operational experience in the aviation branch. The following results were obtained: in terms of information sources, the classification of thrust augmenting ejector nozzles was developed, their advantages and drawbacks were formulated, and the results of available research were analyzed. Investigations of thrust augmenting ejector nozzles for micro-turbojets were analyzed separately. Conclusions. The scientific novelty of the results obtained is as follows: 1) information from numerous sources of literature that clarifies classification features, advantages, and drawbacks of thrust augmenting ejector nozzles, development of these nozzles investigations by theoretical and experimental methods were collected; 2) a very limited number of publications and absence (in open-source literature) of methodology as for designing thrust augmenting ejector nozzles for micro-turbojet engines was discovered. Thus, the necessity of developing a design methodology for thrust augmenting ejector nozzles for micro-turbojets has been justified. The goal and challenges of the following research are outlined.