The influence of wedge diffuser blade number and divergence angle on the performance of a high pressure ratio centrifugal compressor

2018 ◽  
Vol 27 (1) ◽  
pp. 17-24 ◽  
Author(s):  
Yi Wang ◽  
Ge Han ◽  
Xingen Lu ◽  
Junqiang Zhu
Keyword(s):  
High Pressure ◽  
Centrifugal Compressor ◽  
Pressure Ratio ◽  
Divergence Angle ◽  
High Pressure Ratio ◽  
Blade Number

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.

Assessment of Various Turbulence Models in a High Pressure Ratio Centrifugal Compressor With an Object Oriented CFD Code

2012 ◽  
Vol 134 (6) ◽  
Author(s):  
Luca Mangani ◽  
Ernesto Casartelli ◽  
Sebastiano Mauri
Keyword(s):  
Boundary Layer ◽  
High Pressure ◽  
Pressure Gradient ◽  
Centrifugal Compressor ◽  
Pressure Ratio ◽  
Turbulence Models ◽  
Object Oriented ◽  
Adverse Pressure Gradient ◽  
High Mass ◽  
High Pressure Ratio

The flow field in a high pressure ratio centrifugal compressor with a vaneless diffuser has been investigated numerically. The main goal is to assess the influence of various turbulence models suitable for internal flows with an adverse pressure gradient. The numerical analysis is performed with a 3D RANS in-house modified solver based on an object-oriented open-source library. According to previous studies from varying authors, the turbulence model is believed to be the key parameter for the discrepancy between experimental and numerical results, especially at high pressure ratios and high mass-flow. Particular care has been taken at the wall, where a detailed integration of the boundary layer has been applied. The results present different comparisons between the models and experimental data, showing the influence of using advanced turbulence models. This is done in order to capture the boundary layer behavior, especially in large adverse pressure gradient single stage machinery.

Investigation of Self-Recycling-Casing-Treatment (SRCT) Influence on Stability of High Pressure Ratio Centrifugal Compressor With a Volute

2011 ◽  
Author(s):  
Mingyang Yang ◽  
Ricardo Martinez-Botas ◽  
Yangjun Zhang ◽  
Xinqian Zheng ◽  
Takahiro Bamba ◽  
...  
Keyword(s):  
High Pressure ◽  
Numerical Method ◽  
Flow Rate ◽  
Centrifugal Compressor ◽  
Static Pressure ◽  
Pressure Ratio ◽  
Flow Distortion ◽  
Casing Treatment ◽  
High Pressure Ratio ◽  
The Stability

Large feasible operation range is a challenge for high pressure ratio centrifugal compressor of turbocharger in vehicle engine. Self-Recycling-Casing-Treatment (SRCT) is a widely used flow control method to enlarge the range for this kind of compressor. This paper investigates the influence of symmetrical/asymmetrical SRCT (ASRCT) on the stability of a high pressure ratio centrifugal compressor by experimental testing and numerical simulation. Firstly, the performance of the compressor with/without SRCT is tested is measured investigate the influence of flow distortion on the stability of compressor as well as the numerical method validation. Then detailed flow field investigation is conducted by experimental measurement and the numerical method to unveil the reasons for stability enhancement by symmetrical/asymmetrical SRCT. Results show that static pressure distortion at impeller outlet caused by the volute can make passages be confronted with flow distortion less stable than others because of their larger positive slope of T-S pressure ratio performance at small flow rate. SRCT can depress the flow distortion and reduce the slope by non-uniform recycling flow rate at impeller inlet. Moreover, ASRCT can redistribute the recycling flow in circumferential direction according to the asymmetric geometries. When the largest recycling flow rate is imposed on the passage near the distorted static pressure, the slope will be the most effectively reduced. Therefore, the stability is effectively enhanced by the optimized recycling flow device.

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