Numerical Investigation of Cut-Corner in Recess Vaned Casing Treatment

2019 ◽  
Author(s):  
Xiangyi Chen ◽  
Wuli Chu ◽  
Haoguang Zhang ◽  
Bo Luo
Keyword(s):  
Main Flow ◽  
Tip Clearance ◽  
Axial Fan ◽  
Stall Margin ◽  
Casing Treatment ◽  
Stable Operating ◽  
Flow Circulation ◽  
Blade Tip ◽  
Flow Blockage ◽  
Blade Tip Clearance

Abstract This paper studies the effects of cut-corner in the recess vaned casing treatment (RVCT) on the performance of a low-speed axial fan. The solid casing fan and fans with corner-cut RVCT have been simulated respectively. The numerical simulation shows that the introduction of the RVCT and the modification of RVCT cut-corner size bring about obvious changes in fan performance. The RVCT establishes a connection between the RVCT channel and the main flow, contributing to the extra flow circulation in the tip region and resulting in an efficiency penalty for each RVCT configuration. The cut-corner is not necessarily beneficial to the improvement of the stable operating range. With the increase of cut-corner size at the rear wall of RVCT, the improvement of stall margin firstly demonstrates a drop to −8.82% before jumping to over 60%. RVCTs with different cut-corner sizes play different roles in the flow interaction between RVCT channel and main flow, and the stall margin poses a positive relationship with the mass flow passing through RVCT. The size of the cut-corner is responsible for the flow field in RVCT. The RVCT with small cut-corner size functions as a larger blade tip clearance and results in a smaller stall margin than the solid casing fan. Therefore, the size of the cut-corner in RVCT should be large enough to dredge the flow blockage in the tip region and delay the origin of stall.

Mechanism of affecting the performance and internal flow field of an axial flow subsonic compressor with self-recirculation casing treatment

2020 ◽  
pp. 095441002094267
Author(s):  
Hao G Zhang ◽  
Fei Y Dong ◽  
Wei Wang ◽  
Wu L Chu ◽  
Song Yan
Keyword(s):  
Flow Field ◽  
Axial Flow ◽  
Internal Flow ◽  
Leading Edge ◽  
Tip Clearance ◽  
Stall Margin ◽  
Casing Treatment ◽  
Leakage Flows ◽  
Blade Tip ◽  
Compressor Performance

This investigation aims to understand the mechanisms of affecting the axial flow compressor performance and internal flow field with the application of self-recirculation casing treatment. Besides, the potentiality of further enhancing the compressor performance and stability by optimizing the geometric structure of self-recirculation casing treatment is discussed in detail. The results show that self-recirculation casing treatment generates about 7.06, 7.89% stall margin improvements in the experiment and full-annulus unsteady calculation, respectively. Moreover, the compressor total pressure and isentropic efficiency are improved among most of operating points, and the experimental and calculated compressor peak efficiencies are increased by 0.7% and 0.6%, respectively. The comparisons between baseline shroud and self-recirculation casing treatment show that the flow conditions of the compressor rotor inlet upstream are improved well with self-recirculation casing treatment, and the degree of the pressure enhancement in the blade top passage for self-recirculation casing treatment is higher than that for baseline. Further, self-recirculation casing treatment can restrain the leading edge-spilled flows made by the blade tip clearance leakage flows and weaken the blade tip passage blockage. Hence, the flow loss near the rotor top passage is reduced after the application of self-recirculation casing treatment. The rotor performance and stability for self-recirculation casing treatment are greater than those for baseline. The flow-field analyses also indicate that the adverse effects caused by the clearance leakage flows of the blades tip rear are greater than those made by the clearance leakage flows of the blades leading edge. When one injecting part of self-recirculation casing treatment is aligned with the inlet of one blade tip passage, the flow-field quality in the passage is not the best among all the passages between two adjacent injecting parts of self-recirculation casing treatment. Further, the flow-field analyses also indicate that the effect of the relative position between the blade and self-recirculation casing treatment on the flows in the self-recirculation casing treatment may be ignored during the optimization of the recirculating loop configuration.

Experimental and Numerical Investigation of Effect of Center Offset Degree on Compressor Stability With Circumferential Grooved Casing Treatment

2016 ◽  
Author(s):  
HaoGuang Zhang ◽  
Feng Tan ◽  
YanHui Wu ◽  
WuLi Chu ◽  
Wei Wang ◽  
...  
Keyword(s):  
Axial Compressor ◽  
Leading Edge ◽  
Groove Depth ◽  
Tip Clearance ◽  
Central Difference ◽  
Stall Margin ◽  
Casing Treatment ◽  
Compressor Rotor ◽  
Stall Margin Improvement ◽  
Blade Tip

For compressor blade tip stall, one effective way of extending stable operating range is with the application of circumferential grooved casing treatment and its validity was proved by a lot of experimental and numerical investigations. The emphases of most circumferential grooved investigations are focused on the influence of groove depth and groove number on compressor stability, and there is few investigations dealt with the center offset degree of circumferential grooves casing treatment. Hence, an axial compressor rotor with casing treatment (CT) was investigated with experimental and numerical methods to explore the effect of center offset degree on compressor stability and performance. In the work reported here, The center offset degree is defined as the ratio of the central difference between rotor tip axial chord and CT to the axial chord length of rotor tip. When the center of CT is located within the upstream direction of the center of rotor tip axial chord, the value of center offset degree is positive. The experimental and numerical results show that stall margin improvement gained with CT is reduced as the value of center offset degree varies from 0 to 0.33 or −0.33, and the CT with −0.33 center offset degree achieves the lowest value of stall margin improvement at 53% and 73% design rotational speed. The detailed analysis of the flow-field in compressor tip indicates that there is not positive effect made by grooves on leading edge of rotor blade tip when the value of center offset degree is −0.33. As the mass flow of compressor reduces further, tip clearance leakage flow results in the outlet blockage due to the absence of the positive action of grooves near blade tip tail when the value of center offset degree is 0.33. Blockage does not appear in rotor tip passage owing to utilizing the function of all grooves with CT of 0 center offset degree.

Investigation of Blade Tip Interaction With Casing Treatment in a Transonic Compressor: Part 1—Particle Image Velocimetry

2008 ◽  
Author(s):  
M. Voges ◽  
R. Schnell ◽  
C. Willert ◽  
R. Mo¨nig ◽  
M. W. Mu¨ller ◽  
...  
Keyword(s):  
Particle Image Velocimetry ◽  
Particle Image ◽  
Light Sheet ◽  
Tip Clearance ◽  
Stall Margin ◽  
Casing Treatment ◽  
Transonic Compressor ◽  
Image Velocimetry ◽  
Flow Phenomena ◽  
Blade Tip

A single-stage transonic axial compressor was equipped with a casing treatment (CT), consisting of 3.5 axial slots per rotor pitch in order to investigate the predicted extension of the stall margin characteristics both numerically and experimentally. Contrary to most other studies the CT was designed especially accounting for an optimized optical access in the immediate vicinity of the CT, rather than giving maximum benefit in terms of stall margin extension. Part 1 of this two-part contribution describes the experimental investigation of the blade tip interaction with casing treatment using Particle image velocimetry (PIV). The nearly rectangular geometry of the CT cavities allowed a portion of it to be made of quartz glass with curvatures matching the casing. Thus the flow phenomena could be observed with essentially no disturbance caused by the optical access. Two periscope light sheet probes were specifically designed for this application to allow for precise alignment of the laser light sheet at three different radial positions in the rotor passage (87.5%, 95% and 99%). For the outermost radial position the light sheet probe was placed behind the rotor and aligned to pass the light sheet through the blade tip clearance. It was demonstrated that the PIV technique is capable of providing velocity information of high quality even in the tip clearance region of the rotor blades. The chosen type of smoke-based seeding with very small particles (about 0.5 μm in diameter) supported data evaluation with high spatial resolution, resulting in a final grid size of 0.5 × 0.5 mm. The PIV data base established in this project forms the basis for further detailed evaluations of the flow phenomena present in the transonic compressor stage with CT and allows validation of accompanying CFD calculations using the TRACE code. Based on the combined results of PIV measurements and CFD calculations of the same compressor and CT geometry a better understanding of the complex flow characteristics can be achieved, as detailed in Part 2 of this paper.

Stall Margin Improvement by Use of Casing Treatments

2013 ◽  
Author(s):  
Christian T. Pixberg ◽  
Heinz-Peter Schiffer ◽  
M. H. Ross ◽  
J. D. Cameron ◽  
S. C. Morris
Keyword(s):  
Tip Clearance ◽  
Stall Margin ◽  
Tip Clearance Flow ◽  
Casing Treatment ◽  
Transonic Compressor ◽  
Clearance Flow ◽  
Beneficial Impact ◽  
Stall Margin Improvement ◽  
Blade Tip ◽  
Casing Treatments

The beneficial impact of casing treatments on the stall margin of tip-critical compressors has been proven many times. However, there is still no simple and general method to predict their actual effectiveness. The present work considers the axial velocity deficit that is generally observed at the blade tip. This so called tip-blockage is caused by the tip clearance flow. That is investigated for different configurations of the transonic compressor test facilities in Darmstadt and Notre Dame and the results are presented in this paper. Similar circumferential groove casing treatments were applied to different single-stage and 1.5-stage compressors. They all had a tip critical behavior in common, but exhibited different design philosophies. The effectiveness of similar casing treatments on different stages was observed. A new method for calculating tip-blockage is introduced based on compressor performance and the results of a through-flow tool. A direct link between blockage growth and stall margin improvement was found for circumferential grooves casing treatments. Additionally, the results of an axial slot casing treatment are taken into account.

Investigation of Blade Tip Interaction With Casing Treatment in a Transonic Compressor—Part I: Particle Image Velocimetry

2010 ◽  
Vol 133 (1) ◽  
Author(s):  
M. Voges ◽  
R. Schnell ◽  
C. Willert ◽  
R. Mönig ◽  
M. W. Müller ◽  
...  
Keyword(s):  
Particle Image Velocimetry ◽  
Particle Image ◽  
Light Sheet ◽  
Tip Clearance ◽  
Stall Margin ◽  
Casing Treatment ◽  
Transonic Compressor ◽  
Image Velocimetry ◽  
Flow Phenomena ◽  
Blade Tip

A single-stage transonic axial compressor was equipped with a casing treatment (CT), consisting of 3.5 axial slots per rotor pitch in order to investigate the predicted extension of the stall margin characteristics both numerically and experimentally. Contrary to most other studies, the CT was designed especially accounting for an optimized optical access in the immediate vicinity of the CT, rather than giving maximum benefit in terms of stall margin extension. Part I of this two-part contribution describes the experimental investigation of the blade tip interaction with casing treatment using particle image velocimetry (PIV). The nearly rectangular geometry of the CT cavities allowed a portion of it to be made of quartz glass with curvatures matching the casing. Thus, the flow phenomena could be observed with essentially no disturbance caused by the optical access. Two periscope light sheet probes were specifically designed for this application to allow for precise alignment of the laser light sheet at three different radial positions in the rotor passage (87.5%, 95%, and 99%). For the outermost radial position, the light sheet probe was placed behind the rotor and aligned to pass the light sheet through the blade tip clearance. It was demonstrated that the PIV technique is capable of providing velocity information of high quality even in the tip clearance region of the rotor blades. The chosen type of smoke-based seeding with very small particles (about 0.5 μm in diameter) supported data evaluation with high spatial resolution, resulting in a final grid size of 0.5×0.5 mm2. The PIV database established in this project forms the basis for further detailed evaluations of the flow phenomena present in the transonic compressor stage with CT and allows validation of accompanying computational fluid dynamics (CFD) calculations using the TRACE code. Based on the combined results of PIV measurements and CFD calculations of the same compressor and CT geometry, a better understanding of the complex flow characteristics can be achieved, as detailed in Part II of this paper.

Numerical Investigation of Outlet Hub Geometry on the Performance of Large Axial Fan

2013 ◽  
Author(s):  
Chao Yin ◽  
Jun Hu
Keyword(s):  
Aerodynamic Characteristics ◽  
Tip Clearance ◽  
Working Environment ◽  
Outlet Section ◽  
Axial Fan ◽  
Shaft Power ◽  
Numerical Simulation Methods ◽  
Blade Tip ◽  
Fan Blade ◽  
Blade Tip Clearance

The large axial fan’s outlet hub shape changes with its working environment. Usually for saving cost, the hub geometry of fan’s outlet section is roughly processed. There is no geometry specification for the outlet hub section, which makes its structure seriously mismatched with other parts. When a blade which has good performance is fitted into an actual production, it probably couldn’t get a desired result. This shows that the effect of outlet-hub geometry on the performance of large axial fan couldn’t be neglected. To study the effect, four cases of different outlet hub geometries of a large axial fan have been designed and investigated in current paper. Each case has been carefully calculated by using numerical simulation methods. By comparing their aerodynamic characteristics and analyzing flow structures in the tip and hub region of the fan blade, the results show that with the same blade tip clearance, the shape of hub geometry has little effect on the tip flow field. However, the fan efficiency is obviously affected by the hub shape. Straight hub could approve the total pressure of the fan, while shrink hub could reduce shaft power more efficiently. A kind of proper outlet hub geometry could greatly improve the flow performance in the hub region and increase the fan efficiency. So we could choose a proper shape of outlet hub for different working requirements.

Self-Excited Blade Vibration Experimentally Investigated in Transonic Compressors: Rotating Instabilities and Flutter

2015 ◽  
Author(s):  
F. Holzinger ◽  
F. Wartzek ◽  
M. Jüngst ◽  
H.-P. Schiffer ◽  
S. Leichtfuß
Keyword(s):  
Tip Clearance ◽  
Blade Vibration ◽  
Casing Treatment ◽  
Operating Range ◽  
Aerodynamic Damping ◽  
Torsion Mode ◽  
Experimental Campaign ◽  
Blade Tip ◽  
Design Speed ◽  
Blade Tip Clearance

This paper investigates the vibrations that occurred on the blisk rotor of a 1.5-stage transonic research compressor designed for aerodynamic performance validation and tested in various configurations at Technische Universität Darmstadt. During the experimental test campaign self-excited blade vibrations were found near the aerodynamic stability limit of the compressor. The vibration was identified as flutter of the first torsion mode and occurred at design speed as well as in the part-speed region. Numerical investigations of the flutter event at design speed confirmed negative aerodynamic damping for the first torsion mode, but showed a strong dependency of aerodynamic damping on blade tip clearance. In order to experimentally validate the relation between blade tip clearance and aerodynamic damping, the compressor tests were repeated with enlarged blade tip clearance for which stability of the torsion mode was predicted. During this second experimental campaign, strong vibrations of a different mode limited compressor operation. An investigation of this second type of vibration found rotating instabilities to be the source of the vibration. The rotating instabilities first occur as an aerodynamic phenomenon and then develop into self-excited vibration of critical amplitude. In a third experimental campaign, the same compressor was tested with reference blade tip clearance and a non-axisymmetric casing treatment. Performance evaluation of this configuration repeatedly showed a significant gain in operating range and pressure ratio. The gain in operating range means that the casing treatment successfully suppresses the previously encountered flutter onset. The aeroelastic potential of the non-axisymmetric casing treatment is validated by means of the unsteady compressor data. By giving a description of all of above configurations and the corresponding vibratory behavior, this paper contains a comprehensive summary of the different types of blade vibration encountered with a single transonic compressor rotor. By investigating the mechanisms behind the vibrations, this paper contributes to the understanding of flow induced blade vibration. It also gives evidence to the dominant role of the tip clearance vortex in the fluid-structure-interaction of tip critical transonic compressors. The aeroelastic evaluation of the non-axisymmetric casing treatment is beneficial for the design of next generation casing treatments for vibration control.

Numerical study on the effect of blade tip clearance change on stall margin of the transonic axial flow compressor rotor

2021 ◽  
pp. 095765092110368
Author(s):  
Song Yan ◽  
Wuli Chu ◽  
Yu Li ◽  
YuChen Dai
Keyword(s):  
Axial Flow ◽  
Tip Clearance ◽  
Calculation Formula ◽  
Size Change ◽  
Stall Margin ◽  
Axial Flow Compressor ◽  
Compressor Rotor ◽  
Blade Tip ◽  
Flow Compressor ◽  
Blade Tip Clearance

The change of the blade tip clearance size has an important impact on the performance of the compressor. Considering that the performance curve of the compressor is often limited by surge and stall boundaries, this paper used the numerical simulation method to investigate the influence mechanism of the blade tip clearance size change on the stall margin of transonic axial flow compressor rotor. By mathematically decomposing the calculation formula of the stall margin of rotor, the approximate calculation formula of the change of rotor’s stall margin was obtained. Then, the detailed quantitative analysis of the factors that affect the rotor’s stall margin was carried out, the influence weights of various factors on the rotor’s stall margin was also obtained. Finally, the physical mechanism of the change of the rotor’s performance parameters was obtained by the analysis of rotor tip flow field after the blade tip clearance size change.

scholarly journals Creep-Based Reliability Evaluation of Turbine Blade-Tip Clearance with Novel Neural Network Regression

Materials ◽  
2019 ◽  
Vol 12 (21) ◽  
pp. 3552 ◽  
Author(s):  
Chun-Yi Zhang ◽  
Jing-Shan Wei ◽  
Ze Wang ◽  
Zhe-Shan Yuan ◽  
Cheng-Wei Fei ◽  
...  
Keyword(s):  
Neural Network ◽  
High Pressure ◽  
Reliability Analysis ◽  
Response Surface ◽  
Response Surface Method ◽  
Tip Clearance ◽  
Strong Nonlinearity ◽  
Surface Method ◽  
Blade Tip ◽  
Blade Tip Clearance

To reveal the effect of high-temperature creep on the blade-tip radial running clearance of aeroengine high-pressure turbines, a distributed collaborative generalized regression extremum neural network is proposed by absorbing the heuristic thoughts of distributed collaborative response surface method and the generalized extremum neural network, in order to improve the reliability analysis of blade-tip clearance with creep behavior in terms of modeling precision and simulation efficiency. In this method, the generalized extremum neural network was used to handle the transients by simplifying the response process as one extremum and to address the strong nonlinearity by means of its nonlinear mapping ability. The distributed collaborative response surface method was applied to handle multi-object multi-discipline analysis, by decomposing one “big” model with hyperparameters and high nonlinearity into a series of “small” sub-models with few parameters and low nonlinearity. Based on the developed method, the blade-tip clearance reliability analysis of an aeroengine high-pressure turbine was performed subject to the creep behaviors of structural materials, by considering the randomness of influencing parameters such as gas temperature, rotational speed, material parameters, convective heat transfer coefficient, and so forth. It was found that the reliability degree of the clearance is 0.9909 when the allowable value is 2.2 mm, and the creep deformation of the clearance presents a normal distribution with a mean of 1.9829 mm and a standard deviation of 0.07539 mm. Based on a comparison of the methods, it is demonstrated that the proposed method requires a computing time of 1.201 s and has a computational accuracy of 99.929% over 104 simulations, which are improvements of 70.5% and 1.23%, respectively, relative to the distributed collaborative response surface method. Meanwhile, the high efficiency and high precision of the presented approach become more obvious with the increasing simulations. The efforts of this study provide a promising approach to improve the dynamic reliability analysis of complex structures.

Turbine Blade Tip Clearance Measurement Instrumentation

2007 ◽  
Author(s):  
Eric B. Holmquist ◽  
Peter L. Jalbert
Keyword(s):  
Control System ◽  
Real Time ◽  
Tip Clearance ◽  
Engine Control ◽  
Operating Characteristics ◽  
Static Structure ◽  
Engine Operation ◽  
Area Of Interest ◽  
Blade Tip ◽  
Blade Tip Clearance

New and future gas turbine engines are being required to provide greater thrust with improved efficiency, while simultaneously reducing life cycle operating costs. Improved component capabilities enable active control methods to provide better control of engine operation with reduced margin. One area of interest is a means to assess the relative position of rotating machinery in real-time, in particular hot section turbo machinery. To this end, Hamilton Sundstrand is working to develop a real-time means to monitor blade position relative to the engine static structure. This approach may yield other engine operating characteristics useful in assessing component health, specifically measuring blade tip clearance, time-of-arrival, and other parameters. UTC is leveraging its many years of experience with engine control systems to develop a microwave-based sensing device, applicable to both military and commercial engines. The presentation will discuss a hot section engine demonstration of a blade position monitoring system and the control system implications posed by a microwave-based solution. Considerations necessary to implement such a system and the challenges associated with integrating a microwave-based sensor system into an engine control system are discussed.

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