Numerical Study on the Flow Mechanism of Compressor Rotor Blade Vibration under Different Inlet Probe Configurations

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.

Preliminary Research on a High Thrust-to-Weight Ratio of Double-Sided Composite Impeller Microturbine Engine

“…As Figure 13 shows, the calculated efficiency and total pressure ratio of DSCI and turbine have converged with 4.58 million and 5.84 million grids, respectively, which are considered to grid size effect independent. Otherwise mentioned, the com-putation model grid number in the later calculations is about 10.42 million, as shown in Figure 14 [22][23][24][25].…”

Influence of trailing edge radius of intake struts on excitation force and vibration of rotor blades

“…The single-stage load of the gas turbine compressor continues to rise, subjecting blades to increasing alternating aerodynamic force [1]. A kind of vibration problem of turbomachinery blades is a forced response caused by inter-stage interaction [2][3], inlet distortion [4], shedding vortices [5], and stall [6]. Accidents resulting from forced vibration account for 25% of all blade failures, emphasizing their significance [7].…”

Influence of Position of Intake Struts on Unsteady Load and Vibration of First-Stage Rotor

“…With the development of heavy-duty gas turbines, the mass flow rate and single-stage load of compressors and the alternating aerodynamic force borne by blades continue to rise, resulting in increasingly prominent fluid-induced blade vibration [1]. The vibration problems faced by compressor blades mainly include the flutter and forced vibration caused by intake distortion [2,3], rotor-stator interference [4,5], stall and surge [6,7], and drop vortex [8,9]. The accidents caused by the forced vibration of gas turbines account for 25% of the total blade accidents, which cannot be ignored [10].…”