A RESEARCH ON INFLUENCE OF EXHAUST SHAPE ON THERMODYNAMIC AND FLUID DYNAMIC EXHAUST PROPERTIES OF A SMALL-SCALE JET ENGINE
Abstract
The purpose of the study is to evaluate method viability of lowering thermal signature and improvement in fuel efficiency of small turbojet by applying a modification to ejector nozzle assembly of the engine using a CFD model environment. The research examines the numerical 2D and 3D models of the working medium flow in the nozzle duct of a small turbojet engine with a nozzle of specified parameters, as well as the impact of the nozzle and the profiled nozzle on the thermal signature of the small-scale turbojet.
The main task of the study is to obtain a quantitative assessment of potential thermal signature reduction in turbojet exhaust with ejector nozzle comparing to engine without an ejector using comparative CFD analysis of a specially profiled CAD model of ejector nozzle mixer assembly.
The obtained contours of the main exhaust gas parameters for the 2D engine-analog model within the framework of model verification are presented; in addition, the model was verified through air blowing through the 3D model domain of ejector nozzle to initially evaluate the impact of the ejector flow on the exhaust parameters. After verification modeling, by using existing small-scale turbojet specifications for the model to simplify comparison, the main CFD calculation was provided for standard non-modified nozzle and ejector mixer nozzle respectively.
A qualitative conclusion was drawn – profiling the nozzle of a turbojet in combination with the use of an ejector can be used to create vortex flows that intensify the heat transfer between the secondary ejector flow and the primary nozzle flow, thus reducing the overall exhaust temperature. Further study of modification influence on exhaust parameters can significantly improve the mixing in domain, resulting in bigger reduction of temperature and potential improvement in terms of thrust and/or fuel efficiency.
The quantitative results obtained (a reduction in exhaust temperature of about 10-15% depending on distance from the exhaust core) correspond to the real engine model, which can be applied in small-sized aircraft with subsonic cruise speeds to achieve greater payload mass, flight range, or reduced thermal signature of the aircraft.
References
2. M. Badami, P. Nuccio, and A. Signoretto (2013-07-05). Experimental and numerical analysis of a small-scale turbojet engine. Energy Conversion and Management, 76, 225–233. https://doi.org/10.1016/j.enconman.2013.07.043.
3. M. Z. Sogut (2020-06-01). Assessment of small scale turbojet engine considering environmental and thermodynamics performance for flight processes. Energy, 200, 117519. https://doi.org/10.1016/j.energy.2020.117519.
4. J. Large, A. Pesyridis (2019). Investigation of Micro Gas Turbine Systems for High Speed Long Loiter Tactical Unmanned Air Systems. Aerospace, 6(5), 55. https://doi.org/10.3390/aerospace6050055
5. G. Cican, T.-F. Frigioescu, D.-E. Crunteanu, and L. Cristea (February 2023). Micro Turbojet Engine Nozzle Ejector Impact on the Acoustic Emission, Thrust Force and Fuel Consumption Analysis. Aerospace, 10, 162. https://doi.org/10.3390/aerospace10020162 .
6. JetCat, P180NX Gas Turbine Engine specifications (2011-08-01). [Digital source] https://www.jetcat.de/en/productdetails/produkte/jetcat/produkte/RC%20ENGINES/Engines/p180_nx.
7. R. Schmidt, A. Hupfer (2021-08-16). Design and numerical simulation of ejector nozzles for very small turbojet engines. CEAS Aeronautical Journal, 12(4), 18 pages. https://doi.org/10.1007/s13272-021-00537-3.
8. Y. Shan, J.-z. Zhang, and G.-p. Huang (2014-11-19). Experimental and Numerical Studies on Lobed Ejector Exhaust System for Micro Turbojet Engine. Aerospace. https://doi.org/10.1080/19942060.2011.11015358.
9. ANSYS Theory Guide: Realizable k-ε Model. (2009-01-23). [Digital source] https://www.afs.enea.it/project/neptunius/docs/fluent/html/th/node60.htm.
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