Flow instability evolution in high pressure ratio centrifugal compressor with vaned diffuser

2018 ◽  
Vol 98 ◽  
pp. 719-730 ◽  
Author(s):  
Xiao He ◽  
Xinqian Zheng
Keyword(s):  
High Pressure ◽  
Centrifugal Compressor ◽  
Flow Instability ◽  
Pressure Ratio ◽  
Vaned Diffuser ◽  
High Pressure Ratio

Numerical Investigation of Low Solidity Vaned Diffuser Performance in a High-Pressure Centrifugal Compressor: Part I — Influence of Vane Solidity

2007 ◽  
Author(s):  
JongSik Oh ◽  
Giri L. Agrawal
Keyword(s):  
High Pressure ◽  
Centrifugal Compressor ◽  
Pressure Ratio ◽  
Limited Range ◽  
Design Flow ◽  
Design Parameters ◽  
Moderate Pressure ◽  
Vaned Diffuser ◽  
High Pressure Ratio ◽  
Wide Operating

The LSD (Low Solidity Diffuser) is becoming popular in most industrial centrifugal compressor designs because it is found to offer a wide operating flow range while maintaining a similar level of efficiency as in case of conventional vaned diffusers. Most related studies have been for low or moderate pressure ratio machines providing a limited range of design information for high-pressure ratio compressors. As a first step forward information of design parameters, a numerical CFD investigation was applied to a high-pressure industrial centrifugal compressor of design total-to-static pressure ratio of 4.0 with LSDs of NACA65-series profiles whose solidity varies from 0.452 to 0.968 in 5 cases with all the other design parameters fixed. Near design flow, the case of 0.839 solidity has the highest isentropic total-to-static efficiency. Other performance changes are accordingly investigated.

Aerodynamics and Aeroelasticity of Impeller Vane Interactions in a High Pressure Ratio Centrifugal Compressor

2010 ◽  
Author(s):  
S. K. Krishnababu ◽  
M. Imregun ◽  
J. S. Green ◽  
D. Hoyniak
Keyword(s):  
High Pressure ◽  
Centrifugal Compressor ◽  
Computational Study ◽  
Pressure Ratio ◽  
Leading Edge ◽  
Computational Domain ◽  
Trailing Edge ◽  
Vaned Diffuser ◽  
High Pressure Ratio ◽  
Radial Gap

The interaction between impeller and diffuser in a high-pressure ratio centrifugal compressor is considered to have a strong influence on the unsteady flow field, the impeller response and the performance of the compressor. A computational study was performed to investigate the interactions between a backswept impeller and its downstream vaned diffuser with emphasis on the impeller response at 2 different vane settings. The unsteady computations were conducted using two different modelling levels of increasing fidelity. The computational domain included an impeller with 15 main and 15 splitter blades and 22-vane wedge diffuser. A steady-state stage calculation with a mixing-plane interface between the impeller trailing edge and the vane leading edge was conducted first to assess the performance. A whole-annulus unsteady stage calculation was conducted to study the response of the impeller. The effect of radial gap between the impeller trailing edge and the vane leading edge on the performance of the impeller was investigated in some detail. In agreement with other similar studies, the results suggest that there is an optimum value of the radius ratio for best performance.

Numerical Investigation of Low Solidity Vaned Diffuser Performance in a High-Pressure Centrifugal Compressor: Part II—Influence of Vane Stagger

2008 ◽  
Author(s):  
JongSik Oh ◽  
Charles W. Buckley ◽  
Giri L. Agrawal
Keyword(s):  
High Pressure ◽  
Centrifugal Compressor ◽  
Pressure Ratio ◽  
Pressure Rise ◽  
Poor Performance ◽  
Design Flow ◽  
Design Parameters ◽  
Vaned Diffuser ◽  
High Pressure Ratio ◽  
Compressor Performance

As the second part, following the authors’ previous study, the influence of the LSD (Low Solidity Diffuser) vane stagger on high-pressure ratio centrifugal compressor performance is numerically investigated with all the other design parameters fixed, while vane solidities are in the range from 0.70 to 0.85. Vane stagger is varied for 6 cases from 8.55 deg to 22.37 deg with the NACA65-(4A10)06 airfoil profile, and the Stage interface scheme is applied for an interaction treatment. As the vane stagger increases, changing from 10.55 deg to 19.58 deg, the compressor overall performance is generally improved, but two extreme cases of vane stagger of 8.55 deg and 22.37 deg provide poor performance. Vane stagger of 19.58 deg shows the highest efficiency and pressure rise near design flow, while vane stagger of 13.76 deg has the largest operating range with acceptable performance of efficiency and pressure ratio.

Effect of Recirculation Device With Counter Swirl Vane on Performance of High Pressure Ratio Centrifugal Compressor

2011 ◽  
Author(s):  
Hideaki Tamaki
Keyword(s):  
High Pressure ◽  
Mach Number ◽  
Flow Rate ◽  
Centrifugal Compressor ◽  
Pressure Ratio ◽  
Negative Slope ◽  
Tip Leakage Flow ◽  
Recirculation Flow ◽  
Operating Range ◽  
High Pressure Ratio

Centrifugal compressors used for turbochargers need to achieve a wide operating range. The author has developed a high pressure ratio centrifugal compressor with pressure ratio 5.7 for a marine use turbocharger. In order to enhance operating range, two different types of recirculation devices were applied. One is a conventional recirculation device. The other is a new one. The conventional recirculation device consists of an upstream slot, bleed slot and the annular cavity which connects both slots. The new recirculation device has vanes installed in the cavity. These vanes were designed to provide recirculation flow with negative preswirl at the impeller inlet, a swirl counterwise to the impeller rotational direction. The benefits of the application of both of the recirculation devices were ensured. The new device in particular, shifted surge line to a lower flow rate compared to the conventional device. This paper discusses how the new recirculation device affects the flow field in the above transonic centrifugal compressor by using steady 3-D calculations. Since the conventional recirculation device injects the flow with positive preswirl at the impeller inlet, the major difference between the conventional and new recirculation device is the direction of preswirl that the recirculation flow brings to the impeller inlet. This study focuses on two effects which preswirl of the recirculation flow will generate. (1) Additional work transfer from impeller to fluid. (2) Increase or decrease of relative Mach number. Negative preswirl increases work transfer from the impeller to fluid as the flow rate reduces. It increases negative slope on pressure ratio characteristics. Hence the recirculation flow with negative preswirl will contribute to stability of the compressor. Negative preswirl also increases the relative Mach number at the impeller inlet. It moves shock downstream compared to the conventional recirculation device. It leads to the suppression of the extension of blockage due to the interaction of shock with tip leakage flow.

Stability Improvement of a High-Pressure Ratio Centrifugal Compressor by Flow Injection

2020 ◽  
Vol 33 (6) ◽  
pp. 04020072
Author(s):  
Wenchao Zhang ◽  
Xiao He ◽  
Baotong Wang ◽  
Zhenzhong Sun ◽  
Xinqian Zheng
Keyword(s):  
High Pressure ◽  
Centrifugal Compressor ◽  
Flow Injection ◽  
Pressure Ratio ◽  
High Pressure Ratio

Unsteady influence of Self Recirculation Casing Treatment (SRCT) on high pressure ratio centrifugal compressor

2016 ◽  
Vol 58 ◽  
pp. 19-29 ◽  
Author(s):  
Yang Mingyang ◽  
Martines-botas Ricardo ◽  
Deng Kangyao ◽  
Zhang Yangjun ◽  
Zheng Xinqian
Keyword(s):  
High Pressure ◽  
Centrifugal Compressor ◽  
Pressure Ratio ◽  
Casing Treatment ◽  
High Pressure Ratio

Single Versus Dual Recycle System Dynamics of High Pressure Ratio, Low Inertia Centrifugal Compressor Stations

2011 ◽  
Vol 133 (12) ◽  
Author(s):  
K. K. Botros
Keyword(s):  
High Pressure ◽  
Centrifugal Compressor ◽  
Dynamic Instability ◽  
Pressure Ratio ◽  
Check Valve ◽  
Analytical Methodology ◽  
High Pressure Ratio ◽  
Compressor Surge ◽  
Rapid Transients ◽  
Single Versus

Compression systems are designed and operated in a manner to eliminate or minimize the potential for surge, which is a dynamic instability that is very detrimental to the integrity of the compressor unit. Compressor surge can occur when compressors are subjected to rapid transients such as those occurring following an emergency shutdown (ESD) or a power failure, which in turn, requires fast reaction. To prevent this from occurring, compressor stations are designed with single or dual recycle systems with recycle valves, which are required to open upon ESD. There has been extensive debate and confusion as to whether a single recycle or a dual recycle system is required and the circumstances and the conditions under which one system or the other must be used. This paper discusses this crucial design issue in detail and highlights the parameters affecting the decision to employ either system, particularly for high pressure ratio, low inertia compressors. Parameters such as gas volume capacitance (V) in the recycle path, compressor power train inertia, compressor performance characteristics, the recycle valve coefficient (Cv), prestroke and stroke time, and check valve dynamic characteristic are crucial in determining the conditions for dynamic instabilities. A simple analytical methodology based on the perturbation theory is developed that provides a first-cut analysis to determine if a single recycle system is adequate for a given compression system. The concept of an inertia number is then introduced with a threshold value that determines which recycle system to use. Techniques to circumvent compressor surge following ESD are discussed and their respective effectiveness are highlighted including when and if a delay in the fuel cutoff will be effective. An example of a case study with actual field data of a high pressure ratio centrifugal compressor employed in a natural gas compressor station is presented to illustrate the fundamental concept of single versus dual recycle systems.

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