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Artykuły w czasopismach na temat "Self-Recirculating Casing Treatment"
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Wang, Wei, Wuli Chu, Haoguang Zhang i Yanhui Wu. "Experimental study of self-recirculating casing treatment in a subsonic axial flow compressor". Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy 230, nr 8 (10.10.2016): 805–18. http://dx.doi.org/10.1177/0957650916673266.
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Parametric studies of recirculating casing treatment were experimentally performed in a subsonic axial flow compressor. The recirculating casing treatment was parameterized with injector throat height, injection position, and circumferential coverage percentage. Eighteen recirculating casing treatments were tested to study the effects on compressor stability and on the compressor overall performance at three blade speeds. The profiles of recirculating casing treatment were optimized to minimize the losses generated by air recirculation. In the experiment, the stalling mass flow rate, total pressure ratio, and adiabatic efficiency of the compressor were measured to study the steady-state effects on the compressor performance of recirculating casing treatments, and static pressure disturbances on the casing wall were monitored to study the influence on stall dynamics. Results indicate that both the compressor stability and overall performance can be improved through recirculating casing treatment with appropriate geometrical parameters for all the test speeds. The influence on stall margin of one geometric parameter often depends on the choice of others, i.e. the interaction effects exist. In general, the recirculating casing treatment with a moderate injector throat and a large circumferential coverage is the optimal choice to enhance compressor stability. The injector of recirculating casing treatment should be placed upstream of the blade tip leading edge and the injector throat height should be lower than four times the rotor tip gap for the benefits of compressor efficiency. At 71% speed, the blade tip loading is decreased through recirculating casing treatment at the operating condition of near peak efficiency and increased near stall. Moreover, the outlet absolute flow angle is reduced in the tip region and enhanced at lower blade spans for both operating conditions. The stall inceptions are not changed with the implementation of recirculating casing treatment for all the test speeds, but the stall patterns are altered at 33% and 53% speeds, i.e. the stall with two cells is detected in the recirculating casing treatment compared with the solid casing with only one stall cell.
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XIAO, Jun. "Self-Recirculating Casing Treatment for a Radial Compressor". Chinese Journal of Mechanical Engineering 22, nr 04 (2009): 567. http://dx.doi.org/10.3901/cjme.2009.04.567.
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Zhang, Haoguang, Fengyu Jing, Qi Li, Hao Wang i Wuli Chu. "Mechanism Affecting the Performance and Stability of a Centrifugal Impeller by Changing Bleeding Positions of Self-Recirculating Casing Treatment". Aerospace 10, nr 2 (20.01.2023): 104. http://dx.doi.org/10.3390/aerospace10020104.
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This study aimed to investigate the influence of the bleeding position of a self-circulating casing on the aerodynamic performance of a transonic centrifugal compressor. Three types of self-circulating structures with the bleeding positions of 11% Ca (the axial chord length of the blade tip), 14% Ca and 20% Ca from the leading edge of the blade were studied by using the numerical simulation method, with the Krain impeller taken as the research object. It was found that all three types of self-recirculating casing treatments can expand the stable operating range of the impeller, and that at medium and small flow rates, the total pressure ratio and efficiency of the impeller increase gradually with the backward movement of the bleeding position. The self-circulating casing treatment can restrain the development of tip leakage vortex, reduce the blockage area, and improve the stability of the impeller by sucking low-energy fluid. The farther back the bleeding position is, the greater the bleeding mass flow rate of the self-circulating casing for the low-energy fluid in the blade-tip passage becomes. Additionally, a greater inhibition effect on the tip leakage vortex, and a better effect of improving the performance and stability of the impeller, can be obtained. The best air bleeding position is 20% Ca, but it is not directly above the blade-tip blockage center of the solid wall casing passage. Instead, it is downstream of the blockage area.
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Kumar, S. Satish, Dilipkumar Bhanudasji Alone, Shobhavathy M. Thimmaiah, Janaki Rami Reddy Mudipalli, Lakshya Kumar, Ranjan Ganguli, S. B. Kandagal i Soumendu Jana. "Aerodynamic behavior of a transonic axial flow compressor stage with self-recirculating casing treatment". Aerospace Science and Technology 112 (maj 2021): 106587. http://dx.doi.org/10.1016/j.ast.2021.106587.
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Li, Xiangjun, Stephen Spence, Hua Chen, Wuli Chu i Lee Gibson. "Flow Control by Slot Position and Noise Baffle in a Self-Recirculation Casing Treatment on an Axial Fan-Rotor". International Journal of Rotating Machinery 2017 (2017): 1–18. http://dx.doi.org/10.1155/2017/9509212.
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To address the situations where the casing treatment needs to be used to stabilize axial compressors through strong recirculation, this paper initiated a CFD study to investigate how the flow could be suitably controlled in the casing treatment to minimize the efficiency penalty and increase the flow range. A counter-swirl self-recirculation casing treatment was first designed on a low speed axial fan rotor as a baseline case. Then three different slot positions and the influence of including the noise baffle were numerically studied. Based on the understanding of their coeffects, the shorter noise baffle was considered and it was found that the highest efficiency was achieved in the case of the upstream slot when the length of baffle was suitably adjusted to balance the incoming flow and recirculation. The largest flow range was achieved by locating the slot at the most downstream position and using a 50% length baffle since it suitably controlled the recirculating flow and relieved the separation at the low-span region. An optimization study showed that the optimum length of the baffle for efficiency was always larger than for the flow range. Both of the two optimum values reduce as the slot moves downstream.
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Fan, Tengbo, Baotong Wang, Chuanxiang Yan, Wenchao Zhang, Zhaoyun Song i Xinqian Zheng. "Effect of Self-Recirculating Casing Treatment on the Aerodynamic Performance of Ultra-High-Pressure-Ratio Centrifugal Compressors". Processes 11, nr 8 (13.08.2023): 2439. http://dx.doi.org/10.3390/pr11082439.
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The motivation to design a more efficient and compact aircraft engine leads to a continuous increase in overall pressure ratio and decrease in the stage number in compressors. Compared to the traditional multi-stage compressor, a single-stage ultra-high-pressure-ratio centrifugal compressor with a pressure ratio higher than 10.0 can significantly improve the engine’s power-to-weight ratio and fuel economy with a reduced structure complexity. Thus, it has great potential to be adopted in the compression system of advanced aero engines, such as turboshaft engines, in the future. However, the highly narrow Stable Flow Range (SFR) of ultra-high-pressure-ratio centrifugal compressors is a severe restriction for engineering applications. This research focuses on the aerodynamic performance of a ultra-high-pressure-ratio centrifugal compressor, and three-dimensional simulation is employed to investigate the effect of Self-Recirculating Casing Treatment (SRCT) on the performance and stability of the centrifugal compressor. Firstly, the parametric model of SRCT is established to investigate the effect of geometry parameters (rear slot distance and rear slot width) on the aerodynamic performance of the centrifugal compressor. It is concluded that SRCT improves the compressor’s SFR but deteriorates its efficiency. Also, a non-linear and non-monotone relationship exists between the SFR and rear slot distance or width. Then, the flow mechanism behind the effect of SRCT is explored in detail. By introducing the SRCT, an additional flow path is provided across the blade along the circumferential direction, and the behavior of the shock wave and tip leakage flow is significantly changed, resulting in the obviously different loading distribution along the streamwise direction. As a result, the mixing and flow separation loss are enhanced in the impeller flow passage to deteriorate the efficiency. On the other hand, the blockage effect caused by the mixing of slot recirculation and mainstream flow near the impeller inlet increases the axial velocity and reduces the incidence angle below the 90% spanwise section, which is considered to effectively stabilize the impeller flow field and enhance the stability.
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Guo, Yanchao, Xiaochen Mao, Limin Gao i Yibo Yu. "Numerical study on the stability enhancement mechanism of self-recirculating casing treatment in a counter-rotating axial-flow compressor". Engineering Applications of Computational Fluid Mechanics 16, nr 1 (12.05.2022): 1111–30. http://dx.doi.org/10.1080/19942060.2022.2072955.
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Kawase, Motoyuki, i Aldo Rona. "Effect of a Recirculating Type Casing Treatment on a Highly Loaded Axial Compressor Rotor". International Journal of Turbomachinery, Propulsion and Power 4, nr 1 (25.03.2019): 5. http://dx.doi.org/10.3390/ijtpp4010005.
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The tip leakage flow over the blades of an axial compressor rotor adversely affects the axial rotor efficiency and can determine the onset of tip leakage stall. The performance of a new casing treatment concept in the shape of an axisymmetric recirculation channel is explored by steady Reynolds-Averaged Navier–Stokes (RANS) realizable k-ε modelling on the NASA Rotor 37 test case. The modelling exposed a number of attractive features. The casing treatment increased the stall margin at no penalty to the rotor isentropic efficiency over the rotor operating line. A recirculation in the casing channel self-activated and self-adjusted with the rotor loading to provide more passive flow control at higher rotor loading conditions. The nozzle-shaped recirculation channel outflow opposed the tip leakage jet, re-located the casing surface flow interface further downstream, and reduced the rotor blade tip incidence angle. This combination of features makes the new casing treatment particularly attractive for applications to high thrust-to-weight ratio engines, typical of high-performance jet aircraft.
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Kumar, S. Satish, Dilipkumar Bhanudasji Alone, Shobhavathy M. Thimmaiah, Janaki Rami Reddy Mudipalli, Lakshya Kumar, Soumendu Jana, S. B. Kandagal i Ranjan Ganguli. "Aeroelastic Aspects of Axial Compressor Stage With Self-Recirculating Casing Treatment". Journal of Turbomachinery 144, nr 6 (21.02.2022). http://dx.doi.org/10.1115/1.4053385.
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Abstract For successful implementation of casing treatment designs in axial compressors, apart from the stall margin improvement benefits, aeroelasticity also plays a major role. This manuscript addresses the not often discussed aeroelastic aspects of a new discrete type of passive self-recirculating casing treatment (RCT) designed for a transonic axial compressor stage. Experiments are carefully designed for synchronized measurement of the unsteady fluidic disturbances and vibrations during rotating stall for compressor with baseline solid casing and self-RCT. The modal characteristics of the axial compressor rotor-disk assembly are studied experimentally and numerically. Experimentally it is observed that the rotating stall cells excite the blades in their fundamental mode in a compressor with baseline solid casing at the stall flow condition. In contrast, there is no excitation of the blades in the compressor with self-RCT at the same solid casing stall flow condition. Also, the self-RCT compared to the solid casing can significantly reduce the overall vibration levels of the blades that are excited at the stall flow condition. The casing treatment is able to alter the flow field near the tip region of the rotor blade, and hence influencing the forcing function of the rotating cantilever blades to have the aeroelastic benefit.
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Zhang, Hao G., Fei Y. Dong, Wei Wang, Wu L. Chu i Song Yan. "Mechanism of affecting the performance and internal flow field of an axial flow subsonic compressor with self-recirculation casing treatment". Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering, 21.07.2020, 095441002094267. http://dx.doi.org/10.1177/0954410020942675.
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This investigation aims to understand the mechanisms of affecting the axial flow compressor performance and internal flow field with the application of self-recirculation casing treatment. Besides, the potentiality of further enhancing the compressor performance and stability by optimizing the geometric structure of self-recirculation casing treatment is discussed in detail. The results show that self-recirculation casing treatment generates about 7.06, 7.89% stall margin improvements in the experiment and full-annulus unsteady calculation, respectively. Moreover, the compressor total pressure and isentropic efficiency are improved among most of operating points, and the experimental and calculated compressor peak efficiencies are increased by 0.7% and 0.6%, respectively. The comparisons between baseline shroud and self-recirculation casing treatment show that the flow conditions of the compressor rotor inlet upstream are improved well with self-recirculation casing treatment, and the degree of the pressure enhancement in the blade top passage for self-recirculation casing treatment is higher than that for baseline. Further, self-recirculation casing treatment can restrain the leading edge-spilled flows made by the blade tip clearance leakage flows and weaken the blade tip passage blockage. Hence, the flow loss near the rotor top passage is reduced after the application of self-recirculation casing treatment. The rotor performance and stability for self-recirculation casing treatment are greater than those for baseline. The flow-field analyses also indicate that the adverse effects caused by the clearance leakage flows of the blades tip rear are greater than those made by the clearance leakage flows of the blades leading edge. When one injecting part of self-recirculation casing treatment is aligned with the inlet of one blade tip passage, the flow-field quality in the passage is not the best among all the passages between two adjacent injecting parts of self-recirculation casing treatment. Further, the flow-field analyses also indicate that the effect of the relative position between the blade and self-recirculation casing treatment on the flows in the self-recirculation casing treatment may be ignored during the optimization of the recirculating loop configuration.
Rozprawy doktorskie na temat "Self-Recirculating Casing Treatment"
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Kumar, S. Satish. "The Role of Self-Recirculating Casing Treatment on Axial Compressor and Its Aeroelastic Behavior". Thesis, 2019. https://etd.iisc.ac.in/handle/2005/4448.
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The modern-day axial compressor stages in a gas turbine engine play a vital role in generating the high-pressure ratios by operating at the limits of their design. Aerodynamic instabilities such as rotating stall and surge that are detrimental can occur at higher blade loadings as the operating mass flow is reduced. There are possibilities of aeroelastic instabilities such as forced excitations/stall induced blade flutter occurring in compressors that are operating at their design limits. The aim of the thesis is to understand the flow field of the compressor annulus with a detailed survey made near the tip region of the compressor. The knowledge gained from the baseline compressor stage is used in developing a new self-recirculating casing treatment passive flow control device for alleviating stall to a lower mass flow rate at a constant rotor corrected speed. The aeroelastic significance of the flow control device is also studied.
Detailed steady and unsteady measurements are performed at different flow conditions for a compressor with asymmetric rotor tip clearance. Higher flow variations near the tip region indicate the presence of dominant secondary flow effects, and the stall inception is likely to occur near the tip section of the blade. The complex distribution of clearance levels existing in the transonic compressor stage has a negligible influence on the overall performance behavior. Unsteady pressure measurements made along the compressor casing from rotor inlet to rotor exit show the rotating stall behavior. The abrupt nature of rotating stall frequency occurring at about half of the compressor rotor frequency is captured for the solid casing. A strong link with the tip leakage vortex and shock structure interaction near the rotor tip is observed numerically. The spread and radial growth of the low momentum fluid, along with the tendency of leading-edge spillage and backflow near the trailing-edge, suggests that the compressor is about to enter into stall.
A new self-recirculating casing treatment concept is proposed, and a parametric study is carried out to assess the best injection angle for attaining higher stall margin improvements with a negligible drop in compressor performance using steady and unsteady experiments and CFD. A minimum amount of annulus flow is bled that is self-regulating based on the prevailing conditions at the suction port. Injection flow rate increases with an increase in the rotor pressure, with maximum injection flow rate occurring near the stall point. For the 0-Deg skewed self-recirculating casing treatment (RCT) configuration, there is around 6.3% to 9.35% stall margin improvements. There is a gradual increase in peak pressure ratio ranging from 0.17% to 0.44%, which can be attributed to the possibility of the compressor that can be further loaded after the blockage fluid is blown away. There is an improvement in the efficiency ranging from 0.2% to 0.5% with the 0-Deg RCT over the solid casing for a few operating speeds investigated experimentally. The resulting improvements in stall margin and other overall compressor performance parameters can be attributed due to the RCT that is able to overcome a larger loss producing mechanism in comparison to a small quantity of high-pressure fluid being tapped for injection. The unsteady pressures for the casing treatment show that the compressor is un-stalled at the stalling mass flow rate of the solid casing, and the compressor can be throttled further.
The structural dynamics of the compressor rotor are studied, and its modal parameters characterized. The aeroelastic nature of the self-recirculating casing treatment is discussed. At the solid casing stall flow condition, the rotating stall cells excite the blades in their fundamental mode for the compressor with baseline solid casing, and there is no excitation of the blades with the self-recirculating casing treatment. Also, the self-recirculating casing treatment compared to the solid casing is able to reduce the overall vibration levels of the blade at fundamental natural frequencies that are excited at the stalling mass flow condition. The casing treatment alters the flow field near the tip region of the rotor blade and hence influences the forcing function of the rotating cantilever blades.
The present research work contributes to a better understanding of the stall inception process in a typical high-speed axial compressor stage that will assist in better predictions of the compressor stability limit. The asymmetric clearance study showing the negligible influence on the overall performance of the compressor stage will assist in planning for better maintenance schedules for the engine. This study also aids in providing an impetus for compressor designs that can harness the dual benefits of casing treatments for stall margin extension and also for suppressing the aeroelastic excitations.CSIR-National Aerospace Laboratories, Bangalore
Książki na temat "Self-Recirculating Casing Treatment"
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Hathaway, Michael D. Self-recirculating casing treatment concept for enhanced compressor performance. Cleveland, Ohio: National Aeronautics and Space Administration, Glenn Research Center, 2002.
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Center, NASA Glenn Research, red. Self-recirculating casing treatment concept for enhanced compressor performance. Cleveland, Ohio: National Aeronautics and Space Administration, Glenn Research Center, 2002.
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Center, NASA Glenn Research, red. Self-recirculating casing treatment concept for enhanced compressor performance. Cleveland, Ohio: National Aeronautics and Space Administration, Glenn Research Center, 2002.
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Center, NASA Glenn Research, red. Self-recirculating casing treatment concept for enhanced compressor performance. Cleveland, Ohio: National Aeronautics and Space Administration, Glenn Research Center, 2002.
Znajdź pełny tekst źródłaStreszczenia konferencji na temat "Self-Recirculating Casing Treatment"
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Hathaway, Michael D. "Self-Recirculating Casing Treatment Concept for Enhanced Compressor Performance". W ASME Turbo Expo 2002: Power for Land, Sea, and Air. ASMEDC, 2002. http://dx.doi.org/10.1115/gt2002-30368.
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A state-of-the-art CFD code (APNASA) was employed in a computationally based investigation of the impact of casing bleed and injection on the stability and performance of a moderate speed fan rotor wherein the stalling mass flow is controlled by tip flow field breakdown. The investigation was guided by observed trends in endwall flow characteristics (e.g., increasing endwall aerodynamic blockage) as stall is approached, and based on the hypothesis that application of bleed or injection can mitigate these trends. The “best” bleed and injection configurations were then combined to yield a self-recirculating casing treatment concept. The results of this investigation yielded: 1) identification of the fluid mechanisms which precipitate stall of tip critical blade rows, and 2) an approach to recirculated casing treatment which results in increased compressor stall range with minimal or no loss in efficiency. Subsequent application of this approach to a high speed transonic rotor successfully yielded significant improvements in stall range with no loss in compressor efficiency.
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Kumar, S. Satish, Ravi J. Chotalia, Soumedu Jana, Ranjan Ganguli i Kandagal B. Siddanagouda. "Single Stage Axial Compressor Stability Management with Self-Recirculating Casing Treatment". W AIAA Scitech 2019 Forum. Reston, Virginia: American Institute of Aeronautics and Astronautics, 2019. http://dx.doi.org/10.2514/6.2019-0942.
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Iyengar, Vishwas, Lakshmi Sankar i Saeid Niazi. "Assessment of the Self-Recirculating Casing Treatment Concept Applied to Axial Compressors". W 43rd AIAA Aerospace Sciences Meeting and Exhibit. Reston, Virigina: American Institute of Aeronautics and Astronautics, 2005. http://dx.doi.org/10.2514/6.2005-632.
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Zhong, Yiming, WuLi Chu i HaoGuang Zhang. "Numerical Investigation on the Effect of Bleed Port With Self-Recirculating Casing Treatment on the Stability of a 1.5-Stage Transonic Compressor". W ASME Turbo Expo 2019: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/gt2019-90543.
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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.
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Jung, Sewoong, i Robert Pelton. "Numerically Derived Design Guidelines of Self Recirculation Casing Treatment for Industrial Centrifugal Compressors". W ASME Turbo Expo 2016: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/gt2016-56672.
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Casing treatments are a well-known method to extend operating range of centrifugal compressors. A common casing treatment configuration consists of a passage that allows flow from the impeller shroud to be bleed back to the inlet of the stage. This type of casing treatment is used frequently in some applications, including automotive turbochargers, but is rarely used in industrial compressors. An effective casing treatment must be developed specifically to match a given stage. For high volume production products this is practical. For the wide variety of industrial compressor designs, which are produced in low volumes, it is not often cost effective to design a casing treatment to match each application. To help reduce the design effort associated with developing a new casing treatment design, a simple set of design guidelines were developed. These guidelines are based on the results of a computational fluid dynamic (CFD) study of several different class impellers. These guidelines can be used to correctly locate and size the key geometric features of a self-recirculating casing treatment, including slot width, position and cavity vane profile. The study found that the bleed slot position and width were the primary factors controlling performance of the casing treatment. In general, when the slot width is wider and the bleed position is moved further downstream, the range increases but the efficiency falls. The optimal slot width is found to be when the slot area is 23% of the area of inducer eye and positioning the slot near the impeller throat gives a good balance of increased range with minimal efficiency loss. A well designed casing treatment is expected to result in approximately a 25% increase in range while keeping the drop in efficiency less than 0.4 point for the cases considered in this study. In addition, the rise to surge increased more than 60% and turndown almost doubled value with the optimized design.
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Christou, George A., Choon S. Tan, Borislav T. Sirakov, Vai-Man Lei i Giuseppe Alescio. "Characterizing Flow Effects of Ported Shroud Casing Treatment on Centrifugal Compressor Performance". W ASME Turbo Expo 2016: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/gt2016-57070.
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This paper presents an investigation of the effects of Ported Shroud (PS) self-recirculating casing treatment used in turbocharger centrifugal compressors for increasing the operable range. The investigation consists of computing three-dimensional flow in a representative centrifugal compressor with and without PS at various levels of approximations in flow physics and geometrical configuration; this provides an enabler for establishing the causal link between PS flow effects and compressor performance changes. It is shown that the main flow path perceives the PS flow as a combination of flow actuations that include injection and removal of mass flow, and injection of axial momentum and tangential momentum. A computational model in which the presence of the PS is replaced by imposed boundary conditions that reflect the individual flow actuations has thus been formulated and implemented. The removal of a fraction of the inducer mass flow has been determined to be the dominant flow actuation in setting the performance of PS compressors. Mass flow removal reduces the flow blockage associated with the impeller tip leakage flow and increases the diffusion in the main flow path. Adding swirl to the injected flow in the direction opposite to the wheel rotation results in an increase of the stagnation pressure ratio and a decrease of the efficiency. The loss generation in the flow path has been defined to rationalize efficiency changes associated with PS compressor operation.
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Yang, H., D. Nuernberger, E. Nicke i A. Weber. "Numerical Investigation of Casing Treatment Mechanisms With a Conservative Mixed-Cell Approach". W ASME Turbo Expo 2003, collocated with the 2003 International Joint Power Generation Conference. ASMEDC, 2003. http://dx.doi.org/10.1115/gt2003-38483.
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A conservative mixed-cell approach of second-order accuracy is presented and applied to investigate the mechanisms of a self-recirculating casing treatment coupled with a transonic compressor rotor. The mixed cell is a computational cell that may show up at the zonal interface boundary, the face of which is partially solid and partially fluid, if the azimuthal open area of casing treatment does not fully contact with the whole annulus of blade passage. The mixed-cell approach is essentially an extension of the conservative zonal approach by incorporating special mixed-cell handling at the zonal interface and it allows a great flexibility to the grid generation for the patched zones with the best grid topology. The mixed-cell approach is extremely useful for solving the unsteady interaction problems within turbomachinery and its application for simulating the coupled flow through the rotor and the casing treatment is reported. The calculated results and analysis reveal an effective stall margin extension of the casing treatment herein by weakening or even destroying the tip leakage vortex, and expose the different tip flow topologies between the cases with the casing treatment and with the untreated smooth wall. It is found that the casing treatment only slightly decreases the overall efficiency at the design point, but it is beneficial to the overall efficiency at the off-design operating conditions and it can improve the inflow conditions to the downstream stator blade row as well.
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Sharma, Sidharath, Martyn L. Jupp, Ambrose K. Nickson i John M. Allport. "Ported Shroud Flow Processes and Their Effect on Turbocharger Compressor Operation". W ASME Turbo Expo 2017: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/gt2017-63678.
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The ported shroud (PS) self-recirculating casing treatment is widely used to delay the onset of the surge by enhancing the aerodynamic stability of the turbocharger compressor. The increase in the stable operation region of the turbocharger compressor is achieved by recirculating the low momentum fluid that blocks the blade passage to the compressor inlet through a ported shroud cavity. While the ported shroud design delays surge, it comes with a small penalty in efficiency. This work presents an investigation of the flow processes associated with a ported shroud compressor and quantifies the effect of these flow mechanisms on the compressor operation. The full compressor stage is numerically modelled using a Reynolds Averaged Navier-Stokes (RANS) approach employing the shear stress transport (SST) turbulence model for steady state simulations at the design and near surge conditions. The wheel rotation is modelled using a multiple reference frame (MRF) approach. The results show that the flow exits the PS cavity at the near surge condition in the form of three jet-like structures of varying velocity amplitudes. Net entropy generation in the compressor model is used to assess the influence of the ported shroud design on the compressor losses, and the results indicate a small Inlet-PS mixing region is the primary source of entropy generation in the near surge conditions. The analysis also explores the trends of entropy generation at the design and the near surge condition across the different speed lines. The results show that the primary source of entropy generation is the impeller region for the design condition and the inlet-PS cavity region for the near surge condition.
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Thamizullah, Suheab, Abdul Nassar, Antonio Davis, Gaurav Giri i Leonid Moroz. "Parametric Study on Ported Shroud Locations and Geometries for a Turbocharger Compressor". W ASME Turbo Expo 2019: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/gt2019-91245.
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Abstract Turbochargers are commonly used in automotive engines to increase the internal combustion engine performance during off-design operating conditions. When used, the widest operating range for the turbocharger is desired, which is limited on the compressor side by the choke condition and the surge phenomenon. The ported shroud technology is used to extend the operable working range of the compressor, by permitting flow disturbances that block the blade passage to escape and stream back through the shroud cavity to the compressor inlet. The impact of this technology, on a speed-line, at near optimal operating condition, near choke operating condition and near surge operating condition is investigated. The ported shroud (PS) self-recirculating casing treatment is widely used to delay the onset of surge by enhancing the aerodynamic stability of the turbocharger compressor. While the ported shroud design delays surge, it usually comes with a small penalty in efficiency. This research involves designing a single-stage centrifugal compressor for the given specifications, considering the application of an automotive turbocharger. The ported shroud was then introduced in the centrifugal compressor. The performance characteristics were obtained, both at the design and at off-design conditions, both with and without the ported shroud. The performance was compared at various off-design operating speed lines. The entire study, from designing the compressor to optimizing the ported shroud configuration, was performed using the commercial AxSTREAM® software platform. Parametric studies were performed to study the effect of ported shroud axial location along the blade axial length on the operating range and performance. The baseline design, without the ported shroud (P0), and the final geometry with it for all PS inlet axial locations (P1 to P5) were analysed using a commercial CFD package and the results were compared with those from the streamline solver.