Numerical Simulation on Ice Accretion Phenomena in Rotor-Stator Interaction Field

2013 ◽  
Author(s):  
Ryosuke Hayashi ◽  
Makoto Yamamoto
Keyword(s):  
Rotor Blade ◽  
Tip Clearance ◽  
Ice Accretion ◽  
Jet Engine ◽  
Tip Leakage ◽  
Interaction Field ◽  
Stator Vane ◽  
Turbine Component ◽  
Rotor Stator Interaction ◽  
Computational Simplicity

Ice accretion is a phenomenon where super-cooled water droplets impinge and accrete on a body. On a jet engine, ice accretion disturbs the inlet flow, and separated ice pieces can damage to the turbine component, which leads to the severe performance degradation. We simulated icing phenomena in a fan rotor-stator interaction field [1]. This study mainly focused on the icing property at the rotor blade, because the maximum ice thickness of the rotor blade is about seven times larger than that of the stator vane. Moreover, in the study, the effect of the tip clearance was neglected because of the computational simplicity. Therefore, in the present study, we simulate icing phenomena in a rotor-stator interaction field, considering the tip clearance, to clarify the effect of the tip clearance on the ice accretion of the stator vane. The numerical results indicate the tip leakage vortex affect the icing phenomenon at the stator vane.

Measurements of the Tip Clearance Flow for a High-Reynolds-Number Axial-Flow Rotor

1995 ◽  
Vol 117 (4) ◽  
pp. 522-532 ◽  
Author(s):  
W. C. Zierke ◽  
K. J. Farrell ◽  
W. A. Straka
Keyword(s):  
Reynolds Number ◽  
Flow Visualization ◽  
Vortex Core ◽  
Rotor Blade ◽  
High Reynolds Number ◽  
Tip Clearance ◽  
Tip Leakage Vortex ◽  
Tip Leakage ◽  
Blade Tip ◽  
High Reynolds

A high-Reynolds-number pump (HIREP) facility has been used to acquire flow measurements in the rotor blade tip clearance region, with blade chord Reynolds numbers of 3,900,000 and 5,500,000. The initial experiment involved rotor blades with varying tip clearances, while a second experiment involved a more detailed investigation of a rotor blade row with a single tip clearance. The flow visualization on the blade surface and within the flow field indicate the existence of a trailing-edge separation vortex, a vortex that migrates radially upward along the trailing edge and then turns in the circumferential direction near the casing, moving in the opposite direction of blade rotation. Flow visualization also helps in establishing the trajectory of the tip leakage vortex core and shows the unsteadiness of the vortex. Detailed measurements show the effects of tip clearance size and downstream distance on the structure of the rotor tip leakage vortex. The character of the velocity profile along the vortex core changes from a jetlike profile to a wakelike profile as the tip clearance becomes smaller. Also, for small clearances, the presence and proximity of the casing endwall affects the roll-up, shape, dissipation, and unsteadiness of the tip leakage vortex. Measurements also show how much circulation is retained by the blade tip and how much is shed into the vortex, a vortex associated with high losses.

Effects of Tip Clearance on Unsteady Flow Characteristics in an Axial Turbine Stage

2009 ◽  
Author(s):  
Hao Sun ◽  
Jun Li ◽  
Zhenping Feng
Keyword(s):  
Flow Field ◽  
Unsteady Flow ◽  
Rotor Blade ◽  
Suction Side ◽  
Tip Clearance ◽  
Leakage Flow ◽  
Turbine Stage ◽  
Tip Leakage Flow ◽  
Tip Leakage ◽  
Blade Tip

The clearance between the rotor blade tip and casing wall in turbomachinery passages induces leakage flow loss and thus degrades aerodynamic performance of the machine. The flow field in turbomachinery is significantly influenced by the rotor blade tip clearance size. To investigate the effects of tip clearance size on the rotor-stator interaction, the turbine stage profile from Matsunuma’s experimental tests was adopted, and the unsteady flow fields with two tip clearance sizes of 0.67% and 2.00% of blade span was numerical simulated based on Harmonic method using NUMECA software. By comparing with the domain scaling method, the accuracy of the harmonic method was verified. The interaction mechanism between the stator wake and the leakage flow was investigated. It is found that the recirculation induced by the stator wake is separated by a significant “interaction line” from the flow field close to the suction side in the clearance region. The trend of the pressure fluctuation is contrary on both sides of the line. When the stator wakes pass by the suction side, the pressure field fluctuates and the intensity of the tip leakage flow varies. With the clearance size increasing, the “interaction line” is more far away from the suction side and the intensity of tip leakage flow also fluctuates more strongly.

scholarly journals Evaluating the Aerodynamic Impact of Circumferentially Grooved Fan Casing Treatments With Integrated Acoustic Liners on a Turbofan Rotor

2019 ◽  
Author(s):  
Richard F. Bozak ◽  
Gary G. Podboy
Keyword(s):  
Pressure Ratio ◽  
Aerodynamic Performance ◽  
Tip Clearance ◽  
Tip Vortex ◽  
Fan Noise ◽  
Tip Leakage ◽  
Fan Performance ◽  
Acoustic Liners ◽  
Rotor Stator Interaction ◽  
Real Gas Effects

Abstract NASA is investigating the potential of integrating acoustic liners into fan cases to reduce fan noise, while maintaining the fans aerodynamic performance. An experiment was conducted to quantify the aerodynamic impact of circumferentially grooved fan cases with integrated acoustic liners on a 1.5 pressure ratio turbofan rotor. In order to improve the ability to measure small performance changes, fan performance calculations were updated to include real gas effects including the effect of humidity. For all fan cases tested, the measured difference in fan isentropic efficiency was found to be less than the measurement repeatability for a torque-based efficiency calculation (≈ 0.2%), however, an unintended tip clearance difference between configurations makes it difficult to determine if circumferentially grooved fan cases degraded fan performance. Fan exit turbulence measurements showed a 1.5% reduction in total turbulence intensity between hardwall and circumferentially grooved fan cases in the tip vortex region, which is attributed to a disruption in the formation of the tip leakage vortex. This decrease in fan exit turbulence could potentially lead to a 1–2dB reduction in broadband rotor-stator interaction noise. Reduced aerodynamic performance losses associated with over-the-rotor liners could enable further fan noise reduction.

Excitation Order Research in Bladed-Disk Coupling Resonance Condition

2014 ◽  
Vol 472 ◽  
pp. 31-35
Author(s):  
Zheng Qi ◽  
Jian Jun Wang
Keyword(s):  
Rotor Blade ◽  
Resonance Condition ◽  
Working Life ◽  
Disk Model ◽  
Previous Conclusion ◽  
Bladed Disk ◽  
Disk Structure ◽  
Stator Vane ◽  
Rotor Stator Interaction

In order to define the factors of excitation order in bladed-disk coupling resonance condition which affects the working life of the bladed-disk, a more accurate formula of excitation order is proposed. The graph of excitation order applied to a bladed-disk structure is given firstly considering rotor-stator interaction. Then the formula of excitation order is developed according to the similarity of graph between aliasing and excitation order. Finally the formula verification of excitation order is given both numerically and experimentally using a typical bladed-disk model. The study shows that the excitation order applied to bladed-disk structure only has to do with the number of rotor blade and stator vane ,which avoids the uncertainty of previous conclusion.

scholarly journals Measurements of the Tip Clearance Flow for a High Reynolds Number Axial-Flow Rotor: Part 2 — Detailed Flow Measurements

1994 ◽  
Author(s):  
W. C. Zierke ◽  
K. J. Farrell ◽  
W. A. Straka
Keyword(s):  
Reynolds Number ◽  
Rotor Blade ◽  
High Reynolds Number ◽  
Axial Flow ◽  
Tip Clearance ◽  
Flow Measurements ◽  
Tip Leakage Vortex ◽  
Tip Leakage ◽  
Blade Tip ◽  
High Reynolds

A high Reynolds number pump (HIREP) facility has been used to acquire flow measurements in the rotor blade tip clearance region-with blade chord Reynolds numbers of 3,900,000 and 5,500,000. The initial experiment involved rotor blades with varying tip clearances, while a second experiment involved a more detailed investigation of a rotor blade row with a single tip clearance. This paper focuses on detailed flow measurements of the tip leakage vortex. These detailed measurements show the effects of tip clearance size and downstream distance on the structure of the rotor tip leakage vortex. The character of the velocity profile along the vortex core changes from a jet-like profile to a wake-like profile as the tip clearance becomes smaller. These vortex velocity profiles-as well as the levels of unsteadiness-dominate the rotor wake structure in the endwall region. Also, for small clearances, the presence and proximity of the casing endwall affects the roll-up, shape, dissipation, and unsteadiness of the tip leakage vortex. Measurements also show how much circulation is retained by the blade tip and how much is shed into the vortex-a vortex associated with high losses.

Measurements of the Tip Clearance Flow for a High Reynolds Number Axial-Flow Rotor: Part 1 — Flow Visualization

1994 ◽  
Author(s):  
W. C. Zierke ◽  
K. J. Farrell ◽  
W. A. Straka
Keyword(s):  
Reynolds Number ◽  
Flow Visualization ◽  
Rotor Blade ◽  
High Reynolds Number ◽  
Rotor Blades ◽  
Tip Clearance ◽  
Trailing Edge ◽  
Tip Leakage ◽  
High Reynolds ◽  
Edge Separation

A high Reynolds number pump (HIREP) facility has been used to acquire flow measurements in the rotor blade tip clearance region-with blade chord Reynolds numbers of 3,900,000 and 5,500,000. The initial experiment involved rotor blades with varying tip clearances, while a second experiment involved a more detailed investigation of a rotor blade row with a single tip clearance. This paper focuses on flow visualization, employing techniques unique for use in water. The flow visualization on the blade surface and within the flow field indicate that the combination of centripetal acceleration and separation near the trailing edge of the rotor blade suction surface results in the formation of a trailing-edge separation vortex-a vortex which migrates radially upwards along the trailing edge and then turns in the circumferential direction near the casing, moving in the opposite direction of blade rotation. Flow visualization also helps in establishing the trajectory of the tip leakage vortex core. The trailing-edge separation vortex, which lies closer to the endwall than the tip leakage vortex, seems to have an influence on this trajectory. Finally, the periodic interaction of the rotor blades with wakes from the upstream inlet guide vanes-as well as freestream turbulence and vortex structure instabilities-affects the unsteadiness of the vortex.

Analysis of Middle Bearing Failure in Rotor Jet Engine Using Tip-Timing and Tip-Clearance Technique

2014 ◽  
Author(s):  
Edward Rokicki ◽  
Paweł Majewski ◽  
Romuald Rzadkowski ◽  
Ryszard Szczepanik ◽  
Jarosław Spychała ◽  
...  
Keyword(s):  
Numerical Analysis ◽  
Free Vibration ◽  
Rotor Blade ◽  
Aircraft Engine ◽  
Tip Clearance ◽  
Bearing Failure ◽  
Blade Vibration ◽  
Jet Engine ◽  
Compressor Rotor ◽  
Clearance Technique

The reported problem is the failure of the middle bearing in an aircraft rotor engine. Tip-timing and tip-clearance and variance analyses are carried out on a compressor rotor blade in the seventh stage above the middle bearing. The experimental analyses concern both an aircraft engine with a middle bearing in good working order and an engine with a damaged middle bearing. A numerical analysis of the seventh stage blade free vibration are conducted to explain the experimental results. This appears to be an effective method of predicting middle bearing failure. The blade vibration variance increases when there is bearing failure.

scholarly journals Effects of Tip Leakage Flow on the Aerodynamic Performance and Stability of an Axial-Flow Transonic Compressor Stage

Energies ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 4168
Author(s):  
Botao Zhang ◽  
Xiaochen Mao ◽  
Xiaoxiong Wu ◽  
Bo Liu
Keyword(s):  
Boundary Layer ◽  
Shock Wave ◽  
Axial Flow ◽  
Leading Edge ◽  
Rotating Stall ◽  
Tip Clearance ◽  
Leakage Flow ◽  
Tip Leakage Flow ◽  
Tip Leakage ◽  
Transonic Compressor

To explain the effect of tip leakage flow on the performance of an axial-flow transonic compressor, the compressors with different rotor tip clearances were studied numerically. The results show that as the rotor tip clearance increases, the leakage flow intensity is increased, the shock wave position is moved backward, and the interaction between the tip leakage vortex and shock wave is intensified, while that between the boundary layer and shock wave is weakened. Most of all, the stall mechanisms of the compressors with varying rotor tip clearances are different. The clearance leakage flow is the main cause of the rotating stall under large rotor tip clearance. However, the stall form for the compressor with half of the designed tip clearance is caused by the joint action of the rotor tip stall caused by the leakage flow spillage at the blade leading edge and the whole blade span stall caused by the separation of the boundary layer of the rotor and the stator passage. Within the investigated varied range, when the rotor tip clearance size is half of the design, the compressor performance is improved best, and the peak efficiency and stall margin are increased by 0.2% and 3.5%, respectively.

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