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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.
Oleksandr Lytviak; Vasyl Loginov; Sergii Komar; Yevhen Martseniuk. Self-Oscillations of The Free Turbine Speed in Testing Turboshaft Engine with Hydraulic Dynamometer. Aerospace 2021, 8, 114 .
AMA StyleOleksandr Lytviak, Vasyl Loginov, Sergii Komar, Yevhen Martseniuk. Self-Oscillations of The Free Turbine Speed in Testing Turboshaft Engine with Hydraulic Dynamometer. Aerospace. 2021; 8 (4):114.
Chicago/Turabian StyleOleksandr Lytviak; Vasyl Loginov; Sergii Komar; Yevhen Martseniuk. 2021. "Self-Oscillations of The Free Turbine Speed in Testing Turboshaft Engine with Hydraulic Dynamometer." Aerospace 8, no. 4: 114.
In connection with increasing intensification of the working process in a gas turbine engine and increasing requirements for economy, the problem of defining and monitoring the main parts lifetime is becoming more vital. Modern algorithms of the monitoring systems are based on taking into account the levels of part temperature and total equivalent stress throughout the flight cycle. Thermal and stress-strain states of the critical zones of the main parts are determined on the basis of information received from the sensors installed in the engine gas path. Turbine disks are located in the internal cavities of the engine and are cooled by air from the compressor. However, in some designs, the disk cavity can be separated from the place of cooling air bleed by several stages of non-contact labyrinth seals, which will lead to some delay in changing the parameters of the cooling air flow when changing the engine operating mode. It has been observed that if this situation is not taken into account, it can lead to significant errors (more than 40%) in determining the lifetime for the peripheral zone of the disk. At the same time, this error is minimal for the hub and the middle zone of the disk, and the existing monitoring algorithms can be used.
Yevhen Martseniuk. Steady and Transient Thermal State of Turbine Disk Estimation for Life Time Monitoring. Transactions on Aerospace Research 2020, 2020, 21 -29.
AMA StyleYevhen Martseniuk. Steady and Transient Thermal State of Turbine Disk Estimation for Life Time Monitoring. Transactions on Aerospace Research. 2020; 2020 (3):21-29.
Chicago/Turabian StyleYevhen Martseniuk. 2020. "Steady and Transient Thermal State of Turbine Disk Estimation for Life Time Monitoring." Transactions on Aerospace Research 2020, no. 3: 21-29.
This paper deals with simulating the thermal and stress states of the piston and cylinder of a two-stroke diesel engine type D100 for a locomotive using two different methods. The methods are based on the use of various models of piston-cylinder arrangement: one of them uses assembly of the piston-cylinder arrangement and includes all components, but the other uses two models separately: the cylinder and the piston and rings assembly. It was shown that for both methods, the piston temperature fields differ slightly both in zone of the combustion chamber and on the inner surface, and the maximum difference was 8 K in the zone of the first piston ring, but the difference in the cylinder temperature fields is significant, especially in the middle section where the difference reaches 35 K. Transient thermal-stress states of the piston were determined for three programs of engine starting from the cold state (with various initial temperatures equal to 20 ℃; 0 ℃; −20 ℃) and heating it up to its maximum operating mode, and for one program with cooling from maximum mode to idling, every time with stepped loading. Warming up of oil and antifreeze were taken into account. It is shown that temperatures and stresses reach their peaks and then drop in some zones of the piston. The stress reaches a maximum level of 380 MPa at the center of the piston surface from the combustion chamber side when heated with an initial temperature −20 ℃, which is two times more than the stress at steady-state maximum operating mode (192 MPa). The profile of the piston side surface was synthesized taking into account the heating rate. The piston design with different materials of the piston head – VCh60-2, 25H2G2FL, 12DH1MFL – was proposed for D49 and D80 engines. The mean temperature of the piston hottest zone drops by about 40 K in proposed design. The stress also decreased.
Nguyen Van Duong; O. Bilohub; Yevhen Martseniuk. Thermal-Stress State of the Piston During Transient Diesel Operation, Synthesis of the Piston Profile. Advances in Intelligent Systems and Computing 2020, 310 -324.
AMA StyleNguyen Van Duong, O. Bilohub, Yevhen Martseniuk. Thermal-Stress State of the Piston During Transient Diesel Operation, Synthesis of the Piston Profile. Advances in Intelligent Systems and Computing. 2020; ():310-324.
Chicago/Turabian StyleNguyen Van Duong; O. Bilohub; Yevhen Martseniuk. 2020. "Thermal-Stress State of the Piston During Transient Diesel Operation, Synthesis of the Piston Profile." Advances in Intelligent Systems and Computing , no. : 310-324.