Self-Oscillations of The Free Turbine Speed in Testing Turboshaft Engine with Hydraulic Dynamometer

Oleksandr Lytviak; Vasyl Loginov; Sergii Komar; Yevhen Martseniuk

doi:10.3390/aerospace8040114

Aerospace (Apr 2021)

Self-Oscillations of The Free Turbine Speed in Testing Turboshaft Engine with Hydraulic Dynamometer

Oleksandr Lytviak,
Vasyl Loginov,
Sergii Komar,
Yevhen Martseniuk

Affiliations

Oleksandr Lytviak: Department of Automatic Security Systems and Information Technologies, National University of Civil Defense of Ukraine, 61023 Kharkiv, Ukraine
Vasyl Loginov: Aircraft Engines Design Department, N. E. Zhukovsky National Aerospace University Kharkiv Aviation Institute, 61070 Kharkiv, Ukraine
Sergii Komar: Department of Design and Strength of Aircraft and Engines, Ivan Kozhedub Kharkiv National University of the Air Force, 61023 Kharkiv, Ukraine
Yevhen Martseniuk: Aircraft Engines Design Department, N. E. Zhukovsky National Aerospace University Kharkiv Aviation Institute, 61070 Kharkiv, Ukraine

DOI: https://doi.org/10.3390/aerospace8040114
Journal volume & issue: Vol. 8, no. 4
p. 114

Abstract

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Self-oscillations are one of the common problems in the complex automatic system, that can occur due to the features of the workflow and the design of the governor. The development of digital control systems has made it possible to damp self-oscillations by applying complex control laws. However, for hydromechanical systems, such way is unacceptable due to the design complexity and the governor cost. The objective of this work is to determine the parameters of the hydromechanical free turbine speed controller, ensuring the absence of self-oscillations during ground tests of the turboshaft engine with a hydraulic dynamometer. The TV3-117VM engine (Ukraine) with the NR-3VM regulator pump (Ukraine) was selected as the object of the study. However, self-oscillations can also occur in any modifications of the TV3-117 engine with any NR-3 regulator pump. The results of the research may be of interest to engineers and scientists who investigate the dynamics of automatic control systems for similar engines. The paper analyses the nonlinear features of the empirical characteristics of the FTSC leading to self-oscillations of the engine speed. The authors propose the mathematical model of the automatic control system dynamics, which takes into account all the features of the engine and regulator pump. It is shown that the load characteristics of the water brake and the helicopter main rotor can differ significantly. Research of the dynamic characteristics of the TV3-117VM engine was carried out. The analysis showed a good agreement between the calculation results and the field test results, and made it possible to determine the parameters of the controller, which lead to self-oscillations during test. Two cases are considered. The first case includes ground tests of the engine with a water brake; the second case—flight tests of the engine as part of the helicopter’s power plant. The data obtained make it possible to develop recommendations for adjusting the hydromechanical governor without testing it on the engine.

Published in Aerospace

ISSN: 2226-4310 (Online)
Publisher: MDPI AG
Country of publisher: Switzerland
LCC subjects: Technology: Motor vehicles. Aeronautics. Astronautics
Website: http://www.mdpi.com/journal/aerospace

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