Effect of the Foam Metal Casing Treatment on a Low-Speed Axial Compressor

2021 ◽  
Author(s):  
Jia Li ◽  
Dakun Sun ◽  
Ruize Xu ◽  
Xu Dong ◽  
Xiaofeng Sun
Keyword(s):  
Axial Compressor ◽  
Low Speed ◽  
Casing Treatment ◽  
Foam Metal ◽  
Metal Casing

Effect of the Foam Metal Casing Treatment on a Low-Speed Axial Compressor

2020 ◽  
Author(s):  
Jia Li ◽  
Dakun Sun ◽  
Reize Xu ◽  
Xu Dong ◽  
Xiaofeng Sun
Keyword(s):  
Axial Compressor ◽  
Leading Edge ◽  
Metal Ring ◽  
Efficiency Loss ◽  
Stall Inception ◽  
Stall Margin ◽  
Casing Treatment ◽  
Foam Metal ◽  
Metal Casing ◽  
The Impact

Abstract Foam metal is a foam-like substance made out of metal and can be used in flow control, vibration damping and acoustic absorption mainly based on their special physical properties. A kind of foam metal casing treatment is proposed and tested in this study. The impact of the foam metal casing treatment on compressor stability and noise reduction are experimentally investigated. The foam metal selected in the experiments is constructed from ferronickel and its PPI (pores per inch) is 35. The foam metal casing treatment comprises annular support casing and foam metal ring. The effect of foam metal location on stability of the test compressor are investigated by placing shims in support casing. Both time-mean and high-response instrumentation are applied to capture the steady and unsteady compressor performances with the presence of the foam metal casing treatment. 20 microphones of G.R.A.S type are used to measure in-duct acoustic level of the compressor. It is found that the SMI (stall margin improvement) is 36.1% and the efficiency loss is 1.5% at location 7. When foam metal moves to rotor leading edge, the SMI as well as the efficiency loss are getting smaller. The optimal location in the experiments is location 4 where the SMI of compressor is 14.9% and the efficiency loss is 0.1%. The interaction of foam metal with flow in the blade tip region at these locations are investigated and presented in detail. The PSD (power spectrum density) analysis is carried out to show the unsteady signal development in stall inception. The noise attenuation varies in 0.18∼1.6 dB when foam metal is at different locations. Finally, the mechanism and application of the foam metal casing treatment are also discussed.

Foam-Metal Casing Treatment on an Axial Flow Compressor: Stability Improvement and Noise Reduction

2021 ◽  
pp. 1-66
Author(s):  
Dakun Sun ◽  
Jia Li ◽  
Xu Dong ◽  
Ruize Xu ◽  
Xiaofeng Sun
Keyword(s):  
Noise Reduction ◽  
Axial Compressor ◽  
Axial Flow ◽  
Performance Comparison ◽  
Stall Inception ◽  
Stall Margin ◽  
Casing Treatment ◽  
Foam Metal ◽  
Metal Casing ◽  
Flow Compressor

Abstract This paper concerns the stability improvement and noise reduction of an axial compressor caused by the foam metal casing treatment (FMCT). Three FMCTs with different PPI (pores per inch), 20, 35, and 50, are tested experimentally. Two installation locations of foam metal in casing are considered and investigated. At location 1, it is found that the FMCT improves the stall margin by 5.4%~8.7% and the attenuation of compressor noise is up to 5 dB. At location 2, the stall margin is extended by 22.2%~37.1% but increasing the noise mostly. Besides, foam metal at location 1 causes less efficiency loss than that in location 2. Based on the analysis in near-casing pressure distribution, spanwise performance comparison and stall inception, the mechanism of the FMCT for enhancing compressor stability is also discussed.

A Study of Performance and Flow Mechanism of a Slot-Groove Hybrid Casing Treatment in a Low-Speed Compressor

2015 ◽  
Author(s):  
Juan Du ◽  
Fan Li ◽  
Jichao Li ◽  
Ning Ma ◽  
Feng Lin ◽  
...  
Keyword(s):  
Axial Compressor ◽  
Suction Side ◽  
Tip Leakage Flow ◽  
Stall Margin ◽  
Low Speed ◽  
High Entropy ◽  
Casing Treatment ◽  
Tip Leakage ◽  
Flow Loss ◽  
The Difference

A “slot-groove” hybrid casing treatment (CT) is proposed elicited from the recent research on the role of axial location for stall margin improvement (SMI). This combination is expected to display the advantages of both slots and grooves while minimizing their disadvantages. A comparative study is conducted among the “slot-groove”, traditional circumferential groove CT (called the “full-groove” CT) and axial skewed slot CT (known as the “full-slot” CT) to evaluate performance and to explore the stability enhancement and efficiency loss mechanisms of the “slot-groove” CT in a low-speed axial compressor. Results of the combination of laboratory tests and computational fluid dynamics (CFD) data demonstrate that the performance level of the hybrid CT lies in between those two traditional CTs. Simulation results indicate that the difference in the SMIs generated by CTs is closely related to their influences on the vortex trajectory of tip leakage. The stronger and tighter the vortex is, the more the vortex trajectory is inclined toward the blade suction side. Consequently, the interface between tip leakage flow and incoming main flow is pushed downstream and stability is enhanced. The flow loss induced by CTs is explored based on the entropy contours, and the high entropy in the “slot-groove” treated casing produces more efficiency decrease than the “full-groove” CT. Incorporating the “full-slot” CT not only increases entropy generation in the axial skewed slots but also induces considerable flow loss in the blade passage near the casing, thus reducing efficiency most significantly.

Experimental and Numerical Investigation of a Circumferential Groove Casing Treatment in a Low-Speed Axial Research Compressor at Different Tip Clearances

2017 ◽  
Vol 139 (12) ◽  
Author(s):  
Matthias Rolfes ◽  
Martin Lange ◽  
Konrad Vogeler ◽  
Ronald Mailach
Keyword(s):  
Total Pressure ◽  
Solid Wall ◽  
Pressure Ratio ◽  
Axial Compressor ◽  
Chord Length ◽  
Single Stage ◽  
Low Speed ◽  
Casing Treatment ◽  
Operating Range ◽  
Circumferential Groove

The demand of increasing pressure ratios for modern high pressure compressors leads to decreasing blade heights in the last stages. As tip clearances (TC) cannot be reduced to any amount and minimum values might be necessary for safety reasons, the TC ratios of the last stages can reach values notably higher than current norms. This can be intensified by a compressor running in transient operations where thermal differences can lead to further growing clearances. For decades, the detrimental effects of large clearances on an axial compressor's operating range and efficiency are known and investigated. The ability of circumferential casing grooves in the rotor casing to improve the compressor's operating range has also been in the focus of research for many years. Their simplicity and ease of installation are one reason for their continuing popularity nowadays, where advanced methods to increase the operating range of an axial compressor are known. In the authors' previous paper, three different circumferential groove casing treatments were investigated in a single-stage environment in the low-speed axial research compressor at TU Dresden. One of these grooves was able to notably improve the operating range and the efficiency of the single stage compressor at very large rotor TC (5% of chord length). In this paper, the results of tests with this particular groove type in a three stage environment in the low-speed axial research compressor are presented. Two different rotor TC sizes of 1.2% and 5% of tip chord length were investigated. At the small TC, the grooves are almost neutral. Only small reductions in total pressure ratio and efficiency compared to the solid wall can be observed. If the compressor runs with large TC, it notably benefits from the casing grooves. Both, total pressure and efficiency can be improved by the grooves in a similar extent as in single stage tests. Five-hole probe measurements and unsteady wall pressure measurements show the influence of the groove on the flow field. With the help of numerical investigations, the different behavior of the grooves at the two TC sizes will be discussed.

Influence of axial skewed slots on the rotating instability of a low-speed axial compressor

2020 ◽  
pp. 095441002094433
Author(s):  
Tao Li ◽  
Yadong Wu ◽  
Hua Ouyang
Keyword(s):  
Pressure Fluctuations ◽  
Flow Characteristics ◽  
Axial Compressor ◽  
Tip Clearance ◽  
Frequency Spectra ◽  
Stall Margin ◽  
Tip Clearance Flow ◽  
Low Speed ◽  
Casing Treatment ◽  
Rotating Instability

Experimental and numerical analyses were performed on a low-speed axial compressor rotor to investigate the aerodynamic and acoustic effects of axial skewed slots casing treatment on the rotating instability. The experimental results showed that the stall margin could be improved by 8.0% and the frequency broadband hump owing to the rotating instability was suppressed effectively. In the noise spectra, the two dominant broadband humps on both sides of the blade-passing frequency also reduced in amplitude. Full-annulus unsteady computational fluid dynamics simulations were performed near the design condition. Time- and frequency-domain analyses as well as a proper orthogonal decomposition method were applied to obtain the oscillation, frequency, energy and flow characteristics of the rotating instability. Axial skewed slots casing treatment causes a distinct reduction in the amplitude of the pressure fluctuations and frequency spectra with a decrease in the energy of the rotating instability modes. The slots alleviated the tip flow blockage by the periodic injection and removal of the fluid from the passage, which enabled a high tip clearance flow downstream with little impingement on the neighbouring blade tip.

Recirculation-groove coupled casing treatment for a transonic axial compressor

2021 ◽  
Vol 111 ◽  
pp. 106556
Author(s):  
Tien-Dung Vuong ◽  
Kwang-Yong Kim ◽  
Cong-Truong Dinh
Keyword(s):  
Axial Compressor ◽  
Casing Treatment ◽  
Transonic Axial Compressor
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