Failure of a low pressure turbine rotor blade of an aeroengine

Abstract The impact of the unsteadiness in the considered turbulence quantities on the numerical prediction of the aeroelastic behavior of a low-pressure turbine (LPT) rotor blade is evaluated by means of a numerical study. In this context, one of the main objectives of this work is to compare different nonlinear harmonic balance (HB) approaches—one neglecting and one considering the unsteadiness in the employed turbulence models—with a conventional nonlinear solver of the unsteady Reynolds-averaged Navier–Stokes (URANS) equations in the time domain. In order to avoid unphysical oscillations in the turbulence quantities caused by the Gibbs phenomenon in the chosen HB approach, a filter method based on the Lanczos filter is developed. The developed filter method is applied in the course of the HB simulations considering the unsteadiness in the underlying turbulence model. Furthermore, the impact of its application on the solution of the flow field and on the unsteady surface pressure of the rotor blade, in particular, is discussed in the context of this work.

Download Full-text

Blade Row Interaction in a Multistage Low-Pressure Turbine

Volume 1: Turbomachinery ◽

10.1115/91-gt-283 ◽

1991 ◽

Cited By ~ 4

Author(s):

N. Arndt

Keyword(s):

Rotor Blade ◽

Low Pressure ◽

Turbine Rotor ◽

Secondary Flows ◽

Rotor Wake ◽

Low Pressure Turbine ◽

Wake Turbulence ◽

Blade Row ◽

Flow Phenomena ◽

Flow Through

The objective of this work was to enhance the understanding of unsteady flow phenomena in multistage low-pressure turbines. For this purpose, hot-film probe measurements were made downstream of every rotor blade row of a five-stage low-pressure turbine. Rotor-rotor interaction and stator-rotor interaction were observed to have a profound influence on the flow through the low-pressure turbine. Interaction of rotors of different turbine stages occurred owing to the influence of the wakes shed by one rotor blade row upon the flow through the next downstream rotor blade row. This wake-induced rotor-rotor interaction resulted in strongly amplitude-modulated periodic and turbulent velocity fluctuations downstream of every rotor blade row with the exception of the most upstream one. Significantly different wake depths and turbulence levels measured downstream of every rotor blade row at different circumferential positions evidenced the effect of the circumferentially nonuniform stator exit flow upon the next downstream rotor blade row. Stator-rotor interaction also strongly influenced the overturning and the underturning of the rotor wakes, caused by the rotor secondary flows, in the rotor endwall regions. Low rotor wake overturning and underturning, i.e., reduced rotor secondary flow influence, were observed to correlate well with low rotor wake turbulence levels.

Download Full-text

Blade Row Interaction in a Multistage Low-Pressure Turbine

Journal of Turbomachinery ◽

10.1115/1.2929198 ◽

1993 ◽

Vol 115 (1) ◽

pp. 137-146 ◽

Cited By ~ 30

Author(s):

N. Arndt

Keyword(s):

Rotor Blade ◽

Low Pressure ◽

Turbine Rotor ◽

Secondary Flows ◽

Rotor Wake ◽

Low Pressure Turbine ◽

Wake Turbulence ◽

Blade Row ◽

Flow Phenomena ◽

Flow Through

The objective of this work was to enhance the understanding of unsteady flow phenomena in multistage low-pressure turbines. For this purpose, hot-film probe measurements were made downstream of every rotor blade row of a five-stage low-pressure turbine. Rotor–rotor interaction and stator–rotor interaction were observed to have a profound influence on the flow through the low-pressure turbine. Interaction of rotors of different turbine stages occurred owing to the influence of the wakes shed by one rotor blade row upon the flow through the next downstream rotor blade row. This wake-induced rotor–rotor interaction resulted in strongly amplitude-modulated periodic and turbulent velocity fluctuations downstream of every rotor blade row with the exception of the most upstream one. Significantly different wake depths and turbulence levels measured downstream of every rotor blade row at different circumferential positions evidenced the effect of the circumferentially nonuniform stator exit flow upon the next downstream rotor blade row. Stator-rotor interaction also strongly influenced the overturning and the under-turning of the rotor wakes, caused by the rotor secondary flows, in the rotor endwall regions. Low rotor wake overturning and underturning, i.e., reduced rotor secondary flow influence, were observed to correlate well with low rotor wake turbulence levels.

Download Full-text

Influence of Hot Streak Temperature Ratio on Low Pressure Stage of a Vaneless Counter-Rotating Turbine

Volume 6: Turbo Expo 2007, Parts A and B ◽

10.1115/gt2007-27028 ◽

2007 ◽

Author(s):

Qingjun Zhao ◽

Fei Tang ◽

Huishe Wang ◽

Jianyi Du ◽

Xiaolu Zhao ◽

...

Keyword(s):

Shock Wave ◽

High Pressure ◽

Secondary Flow ◽

Low Pressure ◽

Turbine Rotor ◽

Temperature Ratio ◽

High Pressure Turbine ◽

Pressure Stage ◽

Low Pressure Turbine ◽

Hot Streak

In order to explore the influence of hot streak temperature ratio on low pressure stage of a Vaneless Counter-Rotating Turbine, three-dimensional multiblade row unsteady Navier-Stokes simulations have been performed. The predicted results show that hot streaks are not mixed out by the time they reach the exit of the high pressure turbine rotor. The separation of colder and hotter fluids is observed at the inlet of the low pressure turbine rotor. After making interactions with the inner-extending shock wave and outer-extending shock wave in the high pressure turbine rotor, the hotter fluid migrates towards the pressure surface of the low pressure turbine rotor, and the most of colder fluid migrates to the suction surface of the low pressure turbine rotor. The migrating characteristics of the hot streaks are predominated by the secondary flow in the low pressure turbine rotor. The effect of buoyancy on the hotter fluid is very weak in the low pressure turbine rotor. The results also indicate that the secondary flow intensifies in the low pressure turbine rotor when the hot streak temperature ratio is increased. The effects of the hot streak temperature ratio on the relative Mach number and the relative flow angle at the inlet of the low pressure turbine rotor are very remarkable. The isentropic efficiency of the Vaneless Counter-Rotating Turbine decreases as the hot streak temperature ratio is increased.

Download Full-text