Abstract
In the performance test of a compressor, the overstrain alarm of a rotor blade occurred and it was thought to be caused by a large-sized inlet probe. To explain and further avoid the occurrence of this phenomenon, the influences of probe strut configuration on the vibration strain of the compressor rotor blade and the corresponding flow mechanism are studied by using a one-way fluid-structure coupling calculation method. Firstly, the probe strut is simplified as a cylinder with a diameter of 10 mm and located upstream of the inlet stator with the strut wake impinging on the stator blade according to the compressor test. Then, the three scenarios are considered: moving the strut away from the stator blade in axial direction, shifting the strut half of the stator pitch circumferentially, and reducing the strut diameter. The analysis results show that the characteristics of blade vibration are determined by the excitation force on the rotor blade. Under the interaction between the large-sized strut and the compressor, in addition to the excitation force with the strut passing frequency, a force with a lower frequency, namely, the strut-wake-induced frequency, is also observed. The amplitude of the excitation force on the rotor blade depends on the probe configuration. When one of the excitation force frequencies is close to a natural frequency of the rotor blade, the blade resonates, and the amplitude of blade strain varies with the amplitude of the excitation force. In order to reduce the adverse effect of upstream strut wake on the compressor rotor blade vibration, the inlet probe strut should be designed with a smaller diameter and be placed further upstream of the stator in such a way that the strut wake vortex passes through the midpassage of the following stator.
Highlights
The immersed total temperature/total pressure probe is widely used in the aerodynamic performance test of compressors
The inlet probe simplified as a strut with a diameter of 10 mm; the inlet stator and the first-stage rotor in the test compressor were selected as the research objects
When one of the excitation force frequencies is close to a natural frequency of the rotor, the blade resonates, and the amplitude of blade strain varies with the amplitude of the excitation force
Summary
The immersed total temperature/total pressure probe is widely used in the aerodynamic performance test of compressors. As a foreign body, the probe obstructs the flow passage and produces wake vortex, resulting in change of the compressor aerodynamic performance and the blade vibration characteristic. Most of the published researches on the interaction between an inlet probe and compressors focus on aerodynamic performance of compressors. The numerical studies by Yang et al [2] showed that the reduction of 1.5-stage compressor performance was related to the diameter and the number, but not the circumferential position of the inlet probe strut. The numerical results of Ma et al [3] showed that the change of compressor performance came from the interaction between the wake vortices shedding from the probe strut and the vortices generated inside the compressor blade passage. The experimental results of Xiang et al [5] showed that the linear cascade loss reached the minimum value when the shedding vortices of the probe strut of 10 mm in diameter passed through the blade passage rather than impinged on the blade
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