Influences of slotted blade on performance and flow structure of a transonic axial compressor

2021 ◽  
pp. 095765092199438
Author(s):  
Guochen Zhang ◽  
Tianyi Gao ◽  
Zhihui Xu ◽  
Pengcheng Liu ◽  
Chengfeng Zhang
Keyword(s):  
Flow Control ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Axial Compressor ◽  
Stability Margin ◽  
Future Research ◽  
Control Effect ◽  
Overall Stability ◽  
Transonic Axial Compressor

Main reason of compressor instability is boundary layer separation on the surface of blades. As one of flow control methods of the compressor, slotted blade has attracted many researchers’ attention because of its simple geometric structure and remarkable flow control effect. In order to evaluate its availability in the compressor, a type of convergent slot is designed to implement in a single-stage transonic axial compressor. Three configurations, i.e. rotor slot, stator slot and rotor-stator combined slot, are introduced to study the aerodynamic performance of compressor by numerical simulations. Furthermore, flow structures have been analyzed to explain the corresponding mechanism. The results show that overall stability margin of the compressor has been improved by flow control with slotted blade. Behavior of the rotor slot is better than that of the stator slot, but due to mass flow leakage in the slot, peak efficiency and chocking mass flow rate of the compressor are decreased by 1.18% and 3.8% respectively. The low momentum flow on pressure surface is sucked into the jet slot of stator blade, which improves the overall stability margin of 0.63%. The combined scheme with slotted rotor and slotted stator has obtained the best aerodynamic behavior with the increase of the overall stability margin of 2.83%. During the future research, main goal will be improvement of the compressor performance and extension of the mass flow rate range.

Stall Warning Using the Rotor Tip Pressure in a Transonic Axial Compressor With Circumferential Grooves

2018 ◽  
Author(s):  
Byeung Jun Lim ◽  
Tae Choon Park ◽  
Young Seok Kang
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Axial Compressor ◽  
Rotating Stall ◽  
Single Stage ◽  
Stall Inception ◽  
Casing Treatment ◽  
Stall Warning ◽  
Transonic Axial Compressor

In this study, characteristics of stall inception in a single-stage transonic axial compressor with circumferential grooves casing treatment were investigated experimentally. Additionally, the characteristic of increasing irregularity in the pressure inside circumferential grooves as the compressor approaches the stall limit was applied to the stall warning method. Spike-type rotating stall was observed in the single-stage transonic axial compressor with smooth casing. When circumferential grooves were applied, the stall inception was suppressed and the operating point of the compressor moved to lower flow rate than the stall limit. A spike-like disturbance was developed into a rotating stall cell and then the Helmholtz perturbation was overlapped on it at N = 80%. At N = 70 %, the Helmholtz perturbation was observed first and the amplitude of the wave gradually increased as mass flow rate decreased. At N = 60%, spike type stall inceptions were observed intermittently and then developed into continuous rotating stall at lower mass flow rate. Pressure measured at the bottom of circumferential grooves showed that the level of irregularity of pressure increased as flow rate decreased. Based on the characteristic of increasing irregularity of the pressure signals inside the circumferential grooves as stall approaches, an autocorrelation technique was applied to the stall warning. This technique could be used to provide warning against stall and estimate real-time stall margins in compressors with casing treatments.

Numerical Simulation of the Performance of an Axial Compressor Operating With Supercritical Carbon Dioxide

2018 ◽  
Author(s):  
Jinlan Gou ◽  
Wei Wang ◽  
Can Ma ◽  
Yong Li ◽  
Yuansheng Lin ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Numerical Simulation ◽  
Supercritical Carbon Dioxide ◽  
Critical Point ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Axial Compressor ◽  
Brayton Cycle ◽  
Supercritical Carbon

Using supercritical carbon dioxide (SCO2) as the working fluid of a closed Brayton cycle gas turbine is widely recognized nowadays, because of its compact layout and high efficiency for modest turbine inlet temperature. It is an attractive option for geothermal, nuclear and solar energy conversion. Compressor is one of the key components for the supercritical carbon dioxide Brayton cycle. With established or developing small power supercritical carbon dioxide test loop, centrifugal compressor with small mass flow rate is mainly investigated and manufactured in the literature; however, nuclear energy conversion contains more power, and axial compressor is preferred to provide SCO2 compression with larger mass flow rate which is less studied in the literature. The performance of the axial supercritical carbon dioxide compressor is investigated in the current work. An axial supercritical carbon dioxide compressor with mass flow rate of 1000kg/s is designed. The thermodynamic region of the carbon dioxide is slightly above the vapor-liquid critical point with inlet total temperature 310K and total pressure 9MPa. Numerical simulation is then conducted to assess this axial compressor with look-up table adopted to handle the nonlinear variation property of supercritical carbon dioxide near the critical point. The results show that the performance of the design point of the designed axial compressor matches the primary target. Small corner separation occurs near the hub, and the flow motion of the tip leakage fluid is similar with the well-studied air compressor. Violent property variation near the critical point creates troubles for convergence near the stall condition, and the stall mechanism predictions are more difficult for the axial supercritical carbon dioxide compressor.

Stall Inception and Development Process Due to Tip Leakage Flow in Axial Compressor Rotor Blades Row

2014 ◽  
Vol 30 (3) ◽  
pp. 307-313 ◽  
Author(s):  
R. Taghavi-Zenou ◽  
S. Abbasi ◽  
S. Eslami
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Axial Compressor ◽  
Leading Edge ◽  
Rotor Blades ◽  
Leakage Flow ◽  
Tip Leakage Flow ◽  
Tip Leakage ◽  
Compressor Rotor

ABSTRACTThis paper deals with tip leakage flow structure in subsonic axial compressor rotor blades row under different operating conditions. Analyses are based on flow simulation utilizing computational fluid dynamic technique. Three different circumstances at near stall condition are considered in this respect. Tip leakage flow frequency spectrum was studied through surveying instantaneous static pressure signals imposed on blades surfaces. Results at the highest flow rate, close to the stall condition, showed that the tip vortex flow fluctuates with a frequency close to the blade passing frequency. In addition, pressure signals remained unchanged with time. Moreover, equal pressure fluctuations at different passages guaranteed no peripheral disturbances. Tip leakage flow frequency decreased with reduction of the mass flow rate and its structure was changing with time. Spillage of the tip leakage flow from the blade leading edge occurred without any backflow in the trailing edge region. Consequently, various flow structures were observed within every passage between two adjacent blades. Further decrease in the mass flow rate provided conditions where the spilled flow ahead of the blade leading edge together with trailing edge backflow caused spike stall to occur. This latter phenomenon was accompanied by lower frequencies and higher amplitudes of the pressure signals. Further revolution of the rotor blade row caused the spike stall to eventuate to larger stall cells, which may be led to fully developed rotating stall.

Evaluation of Axial Compressor Characteristics Under Overspray Condition

2013 ◽  
Author(s):  
Chihiro Myoren ◽  
Yasuo Takahashi ◽  
Manabu Yagi ◽  
Takanori Shibata ◽  
Tadaharu Kishibe
Keyword(s):  
Gas Turbine ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Water Mass ◽  
Pressure Ratio ◽  
Axial Compressor ◽  
Test Facility ◽  
Compressor Performance ◽  
Water Mass Flow Rate

An axial compressor was developed for an industrial gas turbine equipped with a water atomization cooling (WAC) system, which is a kind of inlet fogging technique with overspray. The compressor performance was evaluated using a 40MW-class test facility for the advanced humid air turbine system. A prediction method to estimate the effect of WAC was developed for the design of the compressor. The method was based on a streamline curvature (SLC) method implementing a droplet evaporation model. Four test runs with WAC have been conducted since February 2012. The maximum water mass flow rate was 1.2% of the inlet mass flow rate at the 4th test run, while the design value was 2.0%. The results showed that the WAC decreased the inlet and outlet temperatures compared with the DRY (no fogging) case. These decreases changed the matching point of the gas turbine, and increased the mass flow rate and the pressure ratio by 1.8% and 1.1%, respectively. Since prediction results agreed with the results of the test run qualitatively, the compressor performance improvement by WAC was confirmed both experimentally and analytically. The test run with the design water mass flow rate is going to be conducted in the near future.

scholarly journals Experimental Investigation of the Flow Mechanisms and the Performance Change of a Highly Loaded Axial Compressor Stage with/without Stator Hub Clearance

2019 ◽  
Vol 9 (23) ◽  
pp. 5134
Author(s):  
Baojie Liu ◽  
Ying Qiu ◽  
Guangfeng An ◽  
Xianjun Yu
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Three Dimensional ◽  
Axial Compressor ◽  
Large Mass ◽  
Small Mass ◽  
Flow Structures ◽  
Leakage Flow ◽  
Corner Separation

Three-dimensional corner separation is common in axial compressors, which can lead to large flow loss and blockage especially when it evolves into the corner stall (open separation). In this paper, the evolution of the three-dimensional flow structures inside a cantilevered stator of a 1.5 stage low-speed highly loaded axial compressor as the stator hub clearance varies, and its effect on the whole compressor performance are investigated experimentally. Firstly, when the stator hub is sealed, the hub corner stall will occur at small mass flow rate conditions. Then, when a very small stator hub clearance is introduced, the leakage flow tends to strengthen the hub corner separation at large mass flow rate conditions and prompts the occurrence of hub corner stall as the mass flow rate decreases. This is mainly caused by the fact that the leakage flow has relatively low energy due to the viscosity effect in the clearance and large flow loss generation as the clearance flow comes across and mixes with the transverse secondary flow. Finally, when the stator hub clearance increases, the effect of the flow viscosity becomes very weak and could be ignored, so the enhanced leakage flow can suppress the transverse migration of the low energy flow near the hub, and the hub corner separation at large mass flow rate conditions could be weakened and the hub corner stall at small mass flow rate conditions could be removed or delayed. As the stator hub clearance varies, the flow structures inside the stator passage could be summarized into five typical flow structures, and this is closely associated with the performance of the compressor.

Effects of Using Hydrogen-Rich Syngas in Industrial Gas Turbines While Maintaining Fuel Flexibility on a Multistage Axial Compressor Design

2012 ◽  
Author(s):  
Pascal Nucara ◽  
Abdulnaser Sayma
Keyword(s):  
Natural Gas ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Gas Turbines ◽  
Axial Compressor ◽  
Critical Parameters ◽  
Gas Combustion ◽  
Fuel Flexibility ◽  
Multistage Axial Compressor

Current gas turbine technology for power generation is generally optimised for natural gas. Recently the use of Low Calorific Value (LCV) fuels gained interest, particularly, Hydrogen rich syngas resulting from coal and solid waste gasification. When LCV fuels are used the performance and behaviour of the engines could significantly change and modifications may be needed. For instance, due to the relatively low heating value of the syngas, higher fuel mass flow rate is required compared to the natural gas combustion case. This leads to a decrease of demand for air from the compressor, which results in increased back pressure, reduction of stall margin and possible compressor instability. In a previous work an exploration of some compressor geometry modifications to allow for high fuel flexibility was conducted on a single axial compressor rotor. The investigation provided insights into the effect of blade shape modifications, such as stagger, lean and sweep on rotor performance. With the same purpose of identifying trends rather than producing optimum design, in this study the analysis is extended to a multistage axial compressor. Two different investigations have been performed, both having, as objective, the shifting of the original mass flow rate towards a lower value while maintaining high performance. In the first study the effect of IGV and stator vanes stagger variations only was considered while in a second approach the re-design of the original machine included modifies to rotor’s stagger angles. In order to understand the change in each single blade performance when modifying the original geometry, the variation of critical parameters such as blade loading and diffusion factor has been here considered in first analysis.

Impact Investigation on the Aerodynamic Performance for Seal Leakage at the Stator Root of Multistage Axial Compressor

2020 ◽  
Author(s):  
Qi Wang ◽  
Lanxue Ren ◽  
Zhou Zhang ◽  
Ting Wang ◽  
Mingcong Luo
Keyword(s):  
Numerical Model ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Axial Compressor ◽  
Flow Distribution ◽  
Numerical Approach ◽  
Aerodynamic Performance ◽  
The Impact ◽  
Multistage Axial Compressor

Abstract This paper presents a numerical model based on the mass flow rate of seal leakage. This numerical model is considered as a correct method for 3-D numerical simulation. It can be used to simulate the effect of seal leakage at the stator root of a multistage axial compressor. Implementation of the correct method is using a numerical model based on the flux conservation which can control the mass flow rate of seal leakage accurately at the seal cavity of compressor. The mass flow rate of seal leakage is chosen as the key research parameter on the aerodynamic performance effect of the seal engineering application in a multistage axial compressor. Combined with the 3-D numerical simulation methods, an engineering numerical approach is set up in this study. A nine-stage axial compressor is taken as the research object in this paper and its aerodynamic performance is tested for proving the applicability of the numerical model for seal leakage. In the cases of several operating rotation speeds, numerical results of the nine-stage axial compressor performance characteristic curves are in good agreement with the experimental data. It is considered that the numerical approach based on the simplified numerical model in this paper can predict the performance of multistage axial compressor accurately. Then, comparisons are made against different cases of seal leakage mass flow rate for analyzing the impact of seal leakage increasing on the aerodynamic performance of the nine-stage axial compressor. The main point of comparisons is focused on the changes of the overall performance and the flow distribution in the compressor with the seal leakage changing. The results indicate that performance of multistage axial compressor is degenerated faster and faster with seal leakage increasing in all operating working points. An overall decline is appeared in the flow capacity, working capacity, efficiency and surge margin of the compressor. For the impact investigation on the changes of flow distribution, the total pressure loss coefficient, the relative Mach number contours and the movement of streamlines are studied in different seal leakage cases under several operating working points. The result also shows that stators located in front stages of multistage axial compressor are affected more seriously with the increasing mass flow rate of seal leakage. Under the influence of seal leakage, degradation of flow condition in stators located in front stages is more severely than that in back stages, the total pressure loss coefficient and entropy are increased, and the flow separations at the root of stators in front stages are developed faster with seal leakage increasing. So it can be confirmed that relatively larger flow losses in front stages bring significant impact on the decay of aerodynamic performance for a multistage axial compressor.

Comprehensive Performance Improvement for a 16-Stage Axial Compressor

2021 ◽  
Author(s):  
Grigorii Popov ◽  
Maxim Miheev ◽  
Alexey Vorobyev ◽  
Oleg Baturin ◽  
Vasilii Zubanov
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Pressure Ratio ◽  
Axial Compressor ◽  
Design Parameters ◽  
Air Mass ◽  
Stability Margins ◽  
Gas Dynamic ◽  
Low Efficiency

Abstract The paper describes the process of gas-dynamic modernization of a 16-stage axial compressor of an industrial gas turbine unit. Tests of the baseline variant of the compressor revealed a significant shortfall of efficiency, pressure ratio, and stability margins. In addition, the ongoing work on the modernization of the entire engine sets the task to the authors of not just achieving design parameters but significantly exceeding them (air mass flow rate by 6%, pressure ratio by 2%, adiabatic efficiency by 1% relative to the design values). To achieve these goals, a numerical model of the compressor was developed and validated. The characteristics obtained with its help were carefully analyzed. It was found that the front stage group has low efficiency, and the rear stage group is significantly oversized in terms of mass flow rate. Modernization works were significantly hampered by the presence of many stages and many independent variables. For this reason, the problem was solved in several stages. A separate modernization of the first and rear groups of stages was performed. Moreover, methods of mathematical optimization were used when developing the rear block of 10 stages. Then the working processes of the compressor parts were matched. As a result of the research, a variant was found to modernize the existing 16-stage axial compressor, providing an increase in the air mass flow rate by 18%, adiabatic efficiency by 3.5%, and margins of gas-dynamic stability up to 16%.

scholarly journals Modelling and Quasilinear Control of Compressor Surge and Rotating Stall Vibrations

2010 ◽  
Vol 2010 ◽  
pp. 1-21 ◽  
Author(s):  
Ranjan Vepa
Keyword(s):  
Equilibrium Point ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Axial Compressor ◽  
Rotating Stall ◽  
Controller Synthesis ◽  
Second Step ◽  
Compressor Surge ◽  
Synthesis Approach

An unsteady nonlinear and extended version of the Moore-Greitzer model is developed to facilitate the synthesis of a quasilinear stall vibration controller. The controller is synthesised in two steps. The first step defines the equilibrium point and ensures that the desired equilibrium point is stable. In the second step, the margin of stability at the equilibrium point is tuned or increased by an appropriate feedback of change in the mass flow rate about the steady mass flow rate at the compressor exit. The relatively simple and systematic non-linear modelling and linear controller synthesis approach adopted in this paper clearly highlights the main features on the controller that is capable of inhibiting compressor surge and rotating stall vibrations. Moreover, the method can be adopted for any axial compressor provided its steady-state compressor and throttle maps are known.

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