A New Type of Self-Adaptive Casing Treatment for a Centrifugal Compressor

2010 ◽  
Author(s):  
Tong Wang ◽  
Wei Xu ◽  
Chuangang Gu ◽  
Jun Xiao
Keyword(s):  
Centrifugal Compressor ◽  
Pressure Ratio ◽  
Centrifugal Impeller ◽  
Stable Operation ◽  
Stable Range ◽  
Stall Margin ◽  
Casing Treatment ◽  
Surge Margin ◽  
New Type ◽  
Self Adaptive

Enhancing compressor stall and surge margin is very important for the development of turbo compressors. Casing treatment is an effective method to expand the stall margin and thus the stable operation range but it generally comes with a drop in efficiency. A new type of casing treatment with self-adaptivity for an unshrouded centrifugal impeller is presented in this paper. The idea of the self-adaptive casing treatment is to automatically control the bleeding flow rate through a set of round holes on the stationary shroud casing. When stall is approached, the casing treatment system will redirect the low-momentum fluid to improve the flow in the impeller and to extend its stable range. However, the system will not bleed or bleed a little flow when the operating point is far from the stall point. This decreases the bleeding-recirculation loss and increases the efficiency compared to bleed-slot casing treatment used before. The experimental results show that the centrifugal compressor with the new casing treatment can extend stable range by about 20% while the efficiency over the whole operating range increases by 0.2 to 1.5%. The theoretical results using CFD analyses agree with the experimental ones in the tendency for both pressure ratio and efficiency. Moreover some possible reasons for further enhancing the stable range are suggested in the paper. Based on our experiences, there should be existed a proper combination of impeller rotating speed, position and numbers of bleed port and other parameters that will maximize both surge margin range and efficiency.

Numerical Investigation of a Centrifugal Compressor With a Single Circumferential Groove in Different Types of Diffusers

2017 ◽  
Author(s):  
Xuefei Chen ◽  
Zijian Ai ◽  
Yunfeng Ji ◽  
Guoliang Qin
Keyword(s):  
Centrifugal Compressor ◽  
Stable Operation ◽  
Stable Range ◽  
Vaneless Diffuser ◽  
Vaned Diffuser ◽  
Effective Measure ◽  
Stall Margin ◽  
Casing Treatment ◽  
Circumferential Groove ◽  
Different Types

Enhancing compressor stall and surge has a great importance for the development of turbo compressors. The application of casing treatment is an effective measure to expand the stall margin and stable operation range. Numerical investigations were conducted to predict the performance of a low flow rate centrifugal compressor with circumferential groove casing treatment in diffuser. Numerical cases with different radial location, radial width and axial depth of a circumferential single groove in different types of diffusers (vaned diffuser, half-vaned diffuser, vaneless diffuser) were carried out to compare the results. The computational fluid dynamics analyses results show that the centrifugal compressor with circumferential groove in vaned diffuser can extend stable range by about 9.1% while the efficiency over the whole operating range decreases by 0.2 to 1.7%; the results with half-vaned diffuser and vaneless diffuser can improve stable range less and the efficiency decreases more. Efforts were made to study blade level flow mechanisms to determine how the circumferential groove impacts the compressor’s stall margin and performance. The flow structures in the passage, the tip gap, and the grooves as well as their mutual interactions were plotted and analyzed. The flow transport across the tip gap in the smooth wall and the circumferential grooves were compared.

A Study on the Influence of Hole’s Diameter With Holed Casing Treatment

2011 ◽  
Author(s):  
Wei Xu ◽  
Tong Wang ◽  
Chuangang Gu ◽  
Liang Ding
Keyword(s):  
Centrifugal Compressor ◽  
Numerical Results ◽  
Radial Position ◽  
Bypass Flow ◽  
Stall Margin ◽  
Casing Treatment ◽  
Velocity Magnitude ◽  
Adaptive Effect ◽  
New Type ◽  
Self Adaptive

The holed casing treatment is a new type of casing treatment with self-adaptability for centrifugal compressor with unshrouded impellers. It is demonstrated experimentally and numerically that both of the stall margin and the choked margin of the compressor can be expanded by the treatment. Numerical results indicate that there is a reinjected flow in the holes when the compressor works at low flowrate conditions and a bypass flow at high flowrate conditions. Hole’s diameter is an important parameter for the holed casing treatment. Five cases of different diameter (1.0mm, 1.5mm, 2.0mm, 2.5mm and 3.0mm) were carried out to reveal its influence. Both the stall margin and efficiency are improving with increasing of the hole’s diameter in the cases of diameter below than 2.5mm. At diameter of 2.5mm, the stall margin increment and the efficiency of the compressor are the highest among all 5 cases. However, in the case of 3.0mm, the stable working range enhancing as well as the efficiency is weakened because the velocity magnitude of the reinjected flow decreases. Therefore a key principle of choosing the diameter and the radial position of the hole is presented in the paper to get the best self-adaptive effect: enhancing stable running range as much as possible and keeping higher efficiency.

Numerical Investigation on the Effect of Bleed Port With Self-Recirculating Casing Treatment on the Stability of a 1.5-Stage Transonic Compressor

2019 ◽  
Author(s):  
Yiming Zhong ◽  
WuLi Chu ◽  
HaoGuang Zhang
Keyword(s):  
Pressure Ratio ◽  
Three Dimensional ◽  
Axial Compressor ◽  
Stability Margin ◽  
Axial Position ◽  
Stable Operation ◽  
Stall Margin ◽  
Casing Treatment ◽  
Transonic Compressor ◽  
Compressor Efficiency

Abstract Compared to the traditional casing treatment, the self-recirculating casing treatment (SCT) can improve or not decrease the compressor efficiency while achieving the stall margin improvement. For the bleed port, the main design indicator is to reduce the flow loss caused by suction, while providing sufficient jet flow and jet pressure to the injector. In order to gain a better study of the bleed port stabilization mechanisms, the bleed configuration was parameterized with the bleed port inlet width and the bleed port axial position. Five kinds of recirculating casing treatments were applied to a 1.5-stage transonic axial compressor with the method of three-dimensional unsteady numerical simulation. Fifteen identical self-recirculating devices are uniformly mounted around the annulus. The numerical results show that the SCT can improve compressor total pressure ratio and stability, shift the stall margin towards lower mass flows. Furthermore, it has no impact on compressor efficiency. The optimal case presents that stability margin is improved by 6.7% employing 3.1% of the annulus mass flow. Expanding bleed port inlet width to an intermediate level can further enhance compressor stability, but excessive bleed port inlet width will reduce the stabilization effect. The optimal bleed port position is located in the blocked area of the low energy group at the top of the rotor. In the case of solid casing, stall inception was the tip blockage, which was mainly triggered by the interaction of the tip leakage vortex and passage shock. From radial distribution, the casing treatment predominantly affects the above 70% span. The reduction of tip reflux region by suction effect is the main reason for the extension of stable operation range. The SCT also has an obvious stability improvement in tip blockage stall, while delaying the occurrence of compressor stall.

Simulation on Expanding Steady Working Range of Centrifugal Compressor by Self-Recirculation Casing Treatment

2014 ◽  
Vol 490-491 ◽  
pp. 550-555
Author(s):  
Chuan Lei Yang ◽  
Guang Jun Wang ◽  
Wen Jiang Xu ◽  
Chun Yu Wu
Keyword(s):  
Mach Number ◽  
Centrifugal Compressor ◽  
Pressure Ratio ◽  
Leading Edge ◽  
Simulation Method ◽  
Surface Boundary ◽  
Surface Boundary Layer ◽  
Casing Treatment ◽  
High Pressure Ratio ◽  
Surge Margin

Numerical simulation method is adopted to simulate and research Self-Recirculation Casing Treatment (SRCT) on expanding the scope of steady work of high-pressure-ratio centrifugal compressor, and increase the compressor surge margin. Contrast the influences which are caused by structure sizes of the SRCT on the performance of compressor. The results showed that SRCT make the compressor stable operating range average broaden more than 13% on all kinds of speed, the surge margin increased by 11% at most. During the structure sizes, the distance between the bleed slot and the splitter blade has the largest affect on the performance of centrifugal compressor, followed by the bleed slot width, others have less affect. SRCT make the distribution of the compressor impeller inlet relative Mach number is more uniform, weaken the phenomenon of blade leading edge local high Mach number. It is also decrease the blade inlet positive incidence, inhibit separation of the blade surface boundary layer.

scholarly journals Stall Margin Improvement in a Centrifugal Compressor through Inducer Casing Treatment

2016 ◽  
Vol 2016 ◽  
pp. 1-19
Author(s):  
V. V. N. K. Satish Koyyalamudi ◽  
Quamber H. Nagpurwala
Keyword(s):  
Mass Flow ◽  
Centrifugal Compressor ◽  
Pressure Ratio ◽  
Treatment Technique ◽  
Centrifugal Compressors ◽  
Stall Margin ◽  
Casing Treatment ◽  
Operating Range ◽  
Stable Operating ◽  
Stall Margin Improvement

The increasing trend of high stage pressure ratio with increased aerodynamic loading has led to reduction in stable operating range of centrifugal compressors with stall and surge initiating at relatively higher mass flow rates. The casing treatment technique of stall control is found to be effective in axial compressors, but very limited research work is published on the application of this technique in centrifugal compressors. Present research was aimed to investigate the effect of casing treatment on the performance and stall margin of a high speed, 4 : 1 pressure ratio centrifugal compressor through numerical simulations using ANSYS CFX software. Three casing treatment configurations were developed and incorporated in the shroud over the inducer of the impeller. The predicted performance of baseline compressor (without casing treatment) was in good agreement with published experimental data. The compressor with different inducer casing treatment geometries showed varying levels of stall margin improvement, up to a maximum of 18%. While the peak efficiency of the compressor with casing treatment dropped by 0.8%–1% compared to the baseline compressor, the choke mass flow rate was improved by 9.5%, thus enhancing the total stable operating range. The inlet configuration of the casing treatment was found to play an important role in stall margin improvement.

Numerical Investigation of a Centrifugal Compressor With Holed Casing Treatment

2012 ◽  
Vol 134 (4) ◽  
Author(s):  
Wei Xu ◽  
Tong Wang ◽  
Chuangang Gu ◽  
Liang Ding
Keyword(s):  
Flow Rate ◽  
Centrifugal Compressor ◽  
High Flow ◽  
Hole Diameter ◽  
Low Flow ◽  
Bypass Flow ◽  
Stall Margin ◽  
Casing Treatment ◽  
New Type ◽  
Different Diameters

The holed casing treatment is a new type of casing treatment that has self-adaptability for a centrifugal compressor with unshrouded impeller. It was demonstrated experimentally and numerically that both the stall margin and the choked margin of the compressor were able to be expanded by the treatment. Numerical results indicate that there is reinjected flow in the holes when the compressor works at low flow rate conditions, and bypass flow at high flow rate conditions. The key principles for choosing the diameter and the radial position of the hole are presented in this paper. The hole’s diameter is an important parameter for the holed casing treatment. Five numerical cases with different diameters (1.0 mm, 1.5 mm, 2.0 mm, 2.5 mm and 3.0 mm) were carried out to compare the results. The reinjected flow enters into the impeller passage periodically and it tends to increase when the hole diameter gets larger. In the case of 2.5 mm, both the stall margin increment and the efficiency of the compressor were the highest among the five cases. Unsteady simulations suggest that the reinjected flow is not only periodic in time but also periodic in circumferential direction. This is the reason why only 2% of the flow amounts would get 20% of the working range expansion.

scholarly journals Axial Flow Compressor Stability Enhancement: Circumferential T-Shape Grooves Performance Investigation

Aerospace ◽  
2021 ◽  
Vol 8 (1) ◽  
pp. 12
Author(s):  
Marco Porro ◽  
Richard Jefferson-Loveday ◽  
Ernesto Benini
Keyword(s):  
Vortex Breakdown ◽  
Pressure Ratio ◽  
Axial Flow ◽  
Suction Side ◽  
Treatment Technique ◽  
Tip Leakage Flow ◽  
Stall Inception ◽  
Stall Margin ◽  
Casing Treatment ◽  
Stall Margin Improvement

This work focuses its attention on possibilities to enhance the stability of an axial compressor using a casing treatment technique. Circumferential grooves machined into the case are considered and their performances evaluated using three-dimensional steady state computational simulations. The effects of rectangular and new T-shape grooves on NASA Rotor 37 performances are investigated, resolving in detail the flow field near the blade tip in order to understand the stall inception delay mechanism produced by the casing treatment. First, a validation of the computational model was carried out analysing a smooth wall case without grooves. The comparisons of the total pressure ratio, total temperature ratio and adiabatic efficiency profiles with experimental data highlighted the accuracy and validity of the model. Then, the results for a rectangular groove chosen as the baseline case demonstrated that the groove interacts with the tip leakage flow, weakening the vortex breakdown and reducing the separation at the blade suction side. These effects delay stall inception, improving compressor stability. New T-shape grooves were designed keeping the volume as a constant parameter and their performances were evaluated in terms of stall margin improvement and efficiency variation. All the configurations showed a common efficiency loss near the peak condition and some of them revealed a stall margin improvement with respect to the baseline. Due to their reduced depth, these new configurations are interesting because they enable the use of a thinner light-weight compressor case as is desirable in aerospace applications.

The influence of the trailing edge angle of the micro centrifugal impeller on the performance of the centrifugal compressor

2021 ◽  
pp. 1-15
Author(s):  
Xu Yu-dong ◽  
Li Cong ◽  
Lv Qiong-ying ◽  
Zhang Xin-ming ◽  
Mu Guo-zhen
Keyword(s):  
Centrifugal Compressor ◽  
Pressure Ratio ◽  
Centrifugal Impeller ◽  
Centrifugal Compressors ◽  
Trailing Edge ◽  
Sweep Angle ◽  
Impeller Blade ◽  
Bending Angle ◽  
Edge Angle ◽  
Isentropic Efficiency

In order to study the effect of the trailing edge sweep angle of the centrifugal impeller on the aerodynamic performance of the centrifugal compressor, 6 groups of centrifugal impellers with different bending angles and 5 groups of different inclination angles were designed to achieve different impeller blade trailing edge angle. The computational fluid dynamics (CFD) method was used to simulate and analyze the flow field of centrifugal compressors with different blade shapes under design conditions. The research results show that for transonic micro centrifugal compressors, changing the blade trailing edge sweep angle can improve the compressor’s isentropic efficiency and pressure ratio. The pressure ratio of the compressor shows a trend of increasing first and then decreasing with the increase of the blade bending angle. When the blade bending angle is 45°, the pressure ratio of the centrifugal compressor reaches a maximum of 1.69, and the isentropic efficiency is 67.3%. But changing the inclination angle of the blade trailing edge has little effect on the isentropic efficiency and pressure ratio. The sweep angle of blade trailing edge is an effective method to improve its isentropic efficiency and pressure ratio. This analysis method provides a reference for the rational selection of the blade trailing edge angle, and provides a reference for the design of micro centrifugal compressors under high Reynolds numbers.

Investigation of Recirculating Casing Treatment for Low-Pressure Ratio Mixed-Flow Micro-Compressor

2020 ◽  
Author(s):  
Kewei Xu ◽  
Gecheng Zha
Keyword(s):  
Pressure Ratio ◽  
Numerical Approach ◽  
Efficiency Loss ◽  
Stall Margin ◽  
Design Point ◽  
Casing Treatment ◽  
Final Design ◽  
Upstream Flow ◽  
Total Pressure Ratio ◽  
Good Agreement

Abstract This paper investigates the recirculating casing treatment (RCT) of a low total pressure ratio micro-compressor to achieve stall margin enhancement while minimizing the design point efficiency penalty. Three RCT injection and extraction configurations are studied, including combined slot-duct, ducts only, and slot only. The numerical approach is validated with a tested micro-compressor using RCT. A very good agreement is achieved between the predicted speedlines and the measured results. To minimize the design point efficiency loss, it is observed that the optimal location of extraction and injection is where the recirculated flow rate can be minimized at the design point. To maximize stall margin, extraction location should favor minimizing the tip blockage such as at the location where the tip flow separation of the baseline blade is fully developed. In addition, the slot configuration that generates pre-swirl to the upstream flow is beneficial to improve stall margin due to reduced incidence. The highest stall margin enhancement achieved is 9.49% with the slot geometry that has the extraction at the 62%C chordwise location, but has a design point efficiency loss of 1.9%. Overall, a small efficiency penalty of 0.6% at the design point is achieved for the final design with the stall margin increased by 6.2%.

An Impact of Self-Recirculation Casing Treatment (SRCT) Configurations on Impeller Stall Margin and the Flow Field

2012 ◽  
Author(s):  
Yan Ma ◽  
Guang Xi ◽  
Guangkuan Wu
Keyword(s):  
Flow Field ◽  
High Speed ◽  
Operating Conditions ◽  
Centrifugal Impeller ◽  
Flow Angle ◽  
Stall Margin ◽  
Casing Treatment ◽  
Swirl Velocity ◽  
Inlet Swirl ◽  
Unsteady Simulation

The present paper describes an investigation of stall margin enhancement and a detailed analysis of the impeller flow field due to self-recirculation casing treatment (SRCT) configuration of a high-speed small-size centrifugal impeller. The influence of different SRCT configurations on the impeller flow field at near-stall condition has been analyzed, highlighting the improvement in stall flow ability. This paper also discusses the influence of the SRCT configurations on the inlet flow angle, inlet swirl velocity and loss distribution in the impeller passage to understand the mechanism of the SRCT configurations in enhancing the stall margin of the impeller. The variation of the bleed flow rate at different operating conditions is also presented in this paper. Finally, the time-averaged unsteady simulation results at near-stall point are presented and compared with steady-state solutions.

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