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Effects of the radial blade loading distribution and B parameter on the type of flow instability in a low-speed axial compressor

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Chinese Journal of Aeronautics 2018年第7期31卷 1470-1479页

作者： qiushi li Simin li Tianyu PAN National Key Laboratory of Science and Technology on Aero-Engine Aerothermodynamics Collaborative Innovation Center for Advanced Aero-Engine School of Energy and Power Engineering Beihang University Department of Mechanical Engineering and Materials Science Duke University

Previous studies showed that an axisymmetric hub-initiated disturbance defined as partial surge may initiate the stall of a transonic compressor; to reveal the instability evolution under full-span incompressible flow for different levels of hub loading and B parameter, an experimental investigation is conducted on a single-stage low-speed compressor. Experimental results show that under a uniform inflow condition without inlet flow distortion, a modal-type stall inception dominates in this low-speed compressor. When an inlet screen introducing hub distortion is used to increase the hub loading, a compressor stall is initiated by a modal wave, but large disturbances are present in the hub region before the compressor stall, which become stronger as the hub loading increases. Under high hub loading and large B parameter（implemented by adding hub distortion through an inlet screen and enlarging the outlet plenum volume, respectively）, a compressor stall is triggered by an axisymmetric hub-initiated disturbance, which is much different from the modal-like disturbances. The beginning of this axisymmetric disturbance may be captured over 800 rotor revolutions prior to the onset of stall, and the amplitude grows with time. The disturbance is hub-initiated because the disturbance signal at the hub is detected much earlier than that at the tip; meanwhile, the frequency of this axisymmetric disturbance changes with the length of the inlet duct. The characteristics of instability evolution in the low-speed compressor are also compared with those in a transonic compressor.

关键词： Axisymmetric disturbance B parameter Flow instability Low-speed axial compressor Radial blade loading distribution

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A numerical simulation strategy for a compressor’s underlying axisymmetric characteristic and its application in body force model

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Chinese Journal of Aeronautics 2024年第8期37卷 79-90页

作者： Shijie liU Tianyu PAN qiushi li School of Energy and Power Engineering Beihang UniversityBeijing 100191China Research Institute of Aero-Engine Beihang UniversityBeijing 100191China Key Laboratory of Fluid and Power Machinery Ministry of EducationXihua UniversityChengdu 610039China

Accurate prediction of the aerodynamic response of a compressor under inlet distortion is crucial for next-generation civil aircraft,such as Boundary Layer Ingestion(Bli)silent ***,research on the Body Force(BF)model plays a significant role in achieving this ***,distorted inlet airflow can lead to varying operating conditions across different spatial locations of the compressor,which may cause some regions to operate outside the stability ***,the accuracy of BF model simulations might be *** address this issue,this paper proposes a numerical simulation strategy for acquiring the steady axisymmetric three-dimensional flow field of a compressor operating at low mass flow rates,which is known as the Underlying Axisymmetric Pressure Rise Characteristic(UAPRC).The proposed simulation accounts for two different rotor speeds of a transonic compressor and identifies initial positions in the flow field where deterioration occurs based on prior experimental ***,simulation results are incorporated into the BF model to replicate hub instability observed in *** results demonstrate that this strategy provides valid predictions of the UAPRC of the compressor,thereby addressing the limitations associated with the BF model.

关键词： Compressor partial instability Performance at low mass flow rates Underlying axisymmetric pressure rise characteristic Novel simulation strategy Body force model

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Instability Inception of a Single Rotor Embedded in a Transonic Stage with Partial Surge Inception

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Journal of Thermal Science 2022年第1期31卷 130-140页

作者： PAN Tianyu WU Wenqian ZHENG Mengzong li qiushi Reserach Institute of Aero-Engine Beihang UniversityBeijing 102206China School of Energy and Power Engineering Beihang UniversityBeijing 102206China Key Laboratory of Fluid and Power Machinery Ministry of EducationXihua UniversityChengdu 610039China

Partial surge is a type of instability inception discovered in our previous *** has been confirmed that partial surge is localized in the blade hub region,and the flow oscillation it caused will lead to the stall cells in the rotor *** since all information about partial surge is obtained from the compressor stage experiments,what will happen to the stall process after the stators are removed is also an issue that worth ***,in this paper,a series of experiments are carried out on the single rotor embedded in the transonic compressor stage with partial surge ***,the experimental results under uniform inlet conditions show that,although partial surge appears at high rotor speed in the stage case,it does not occur at any speed in the single rotor ***,it is found by numerical simulation that the absence of partial surge may be due to the insufficient rotor hub loading,so an experiment with increased hub loading is carried out,but still fails to trigger partial ***,the reason why partial surge doesn’t occur in the single rotor is *** these results,it can be concluded that partial surge cannot occur in the single rotor case,and the large-scale comer separation in the stator hub is considered to play an important role in the formation of partial surge.

关键词： transonic rotor instability inception partial surge blade loading corner separation

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Impact of circumferential inlet distortion on different types of stall inceptions in a transonic compressor

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Chinese Journal of Aeronautics 2024年第11期37卷 107-117页

作者： Tianyu PAN Jiandong YAN Hanan LU qiushi li Reserach Institute of Aero-Engine Beihang UniversityBeijing 100191China School of Energy and Power Engineering Beihang UniversityBeijing 100191China Key Laboratory of Fluid and Power Machinery Ministry of EducationXihua UniversityChengdu 610039China

The application of higher bypass ratios and lower pressure ratios significantly reduces specific fuel consumption with the development of turbofan ***,it also increases the risk of flow separation at the intake,leading to severe circumferential non-uniform inlet *** study aimed to present an experimental investigation on instability evolutions of the compressor under circumferential non-uniform inlet *** stall inceptions regarding the different spatial scales and initial locations were selected to investigate this *** experiments were carried out on one tested rig,which the stall inceptions verified with the rotational *** 65%design rotational speed(X),the stall inception was the spike,which was triggered by disturbances within serval pitches scale at the ***,the spike-type stall inception was sensitive to circumferential distortion and led to a shrunk stall margin of the *** the rotational speed increasing to 88%X,the stall inception switched to partial surge,which was induced by the flow blockage in the hub region around the *** results indicated that the partial surge was insusceptible to the circumferential distortion,which caused an extended stall margin with a lower stalled mass flow *** summary,the influence of distortion on the stability of the target compressor was found to be determined by the stall inception.

关键词： Partial surge Circumferential inlet distortion Transonic compressor Stall triggering event Loading distribution

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Study on effects of thickness on airfoil-stall at low Reynolds numbers by cusp-catastrophic model based on GA(W)-1 airfoil

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Chinese Journal of Aeronautics 2020年第5期33卷 1444-1453页

作者： Zhiping li Peng ZHANG Tianyu PAN qiushi li Jian ZHANG National Key Laboratory of Science and Technology on Aero-Engine Aero-thermodynamics Beihang UniversityBeijing 100083China Collaborative Innovation Center for Advanced Aero-Engine Beihang UniversityBeijing 100083China School of Energy and Power Engineering Beihang UniversityBeijing 100083China Key Laboratory of Fluid and Power Machinery Ministry of EducationXihua UniversityChengdu 610039China

The phenomena of an airfoil stall present the behaviors of catastrophe and hysteresis at low Reynolds *** simulation results of two-dimensional airfoil GA(W)-1 show that the width of the hysteresis loop of airfoil stall will gradually decrease and even disappear with the decrease of thickness *** nonlinear characteristics are in accordance with the topological features of the cusp catastrophic *** to the topological invariant principle,a novel topological mapping method is developed to establish the mapping relationship between cusp catastrophic model and stall characteristics of the airfoil,then the effect of thickness ratio on airfoil stall is successfully described quantitatively by cusp catastrophic ***,based on the established topological mapping relationship,combined with the mean flow field of the airfoil stall,potential function approach of cusp catastrophic model is first introduced to interpret the catastrophe and hysteresis of the airfoil stall,and it is found that as the thickness ratio decreases,the system’s maximal potential energy gradually disappears,and the short separation bubble at the leading edge of the airfoil changes to long separation bubble,so the airfoil stall changes from a bistable system to a monostable system.

关键词： Airfoil Catastrophe theory Low Reynolds number Potential function Thickness ratio

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Streamwise-body-force-model for rapid simulation combining internal and external flow fields

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Chinese Journal of Aeronautics 2016年第5期29卷 1205-1212页

作者： Cui Rong li qiushi Pan Tianyu Zhang Jian National Key Laboratory on Aero-Engines Beihang University Collaborative Innovation Center of Advanced Aero-Engine Beihang University Department of Engine Project Aviation Industry Corporation of China

A streamwise-body-force-model （SBFM） is developed and applied in the overall flow simulation for the distributed propulsion system, combining internal and external flow fields. In view of axial stage effects, fan or compressor effects could be simplified as body forces along the streamline. These body forces which are functions of local parameters could be added as source terms in Navier-Stokes equations to replace solid boundary conditions of blades and hubs. The val- idation of SBFM with uniform inlet and distortion inlet of compressors shows that pressure performance characteristics agree well with experimental data. A three-dimensional simulation of the integration configuration, via a blended wing body aircraft with a distributed propulsion system using the SBFM, has been completed. lift coefficient and drag coefficient agree well with wind tunnel test results. Results show that to reach the goal of rapid integrated simulation combining internal and external flow fields, the computational fluid dynamics method based on SBFM is reasonable.

关键词： Aircraft Blended wing body Boundary layer ingestion Distributed propulsion sys-tem Integrated simulations Streamwise-body-force-model

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Hysteresis behaviors of compressor rotating stall with cusp catastrophic model

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Chinese Journal of Aeronautics 2018年第5期31卷 1075-1084页

作者： Zhiping li Peng ZHANG Tianyu PAN qiushi li Jian ZHANG National Key Laboratory of Science and Technology on Aero-Engine Aerothermodynamics Beihang University Collaborative Innovation Center of Advanced Aero-Engine Beihang University School of Energy and Power Engineering Beihang University Department of Mechanical Engineering and Materials Science Duke University

Rotating stall is a complex nonlinear dynamic phenomenon which is always characterized by catastrophe and hysteresis in high aerodynamic-loading compressor. Exploring the key contributing factors and characteristic rules of hysteresis is very important for compressor design and flow instability control. In this paper, a novel model method is proposed to analyze the hysteresis behaviors to extend the understanding of compressor rotating stall. The equilibrium states of compressor system under different conditions are first described based on Moore-Greitzer model. Then,through assessing the stability of the equilibrium points by liapunov＇s theorem, the ratio of shutoff head to compressor characteristic semi-height is found to affect the stall hysteresis： the size of hysteresis loop will gradually decrease, even disappear with the increase of the ratio. Combing the effects of both the ratio and throttle coefficient, the hysteresis behaviors of compressor stall under multi-parameters can be found to be consistent with the topological properties of cusp catastrophic model by Thom＇s catastrophe theory. Finally, according to topological invariant rules, from the perspective of potential function, the equilibrium surface equation of compressor system is developed by standard cusp catastrophic model to describe the various hysteresis behaviors of compressor rotating stall along different control routes.

关键词： Catastrophe theory Compressor Hysteresis Rotating stall Topological analysis

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Effect of system response on partial surge initiated instability in a transonic axial flow compressor

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Chinese Journal of Aeronautics 2022年第2期35卷 117-127页

作者： Tianyu PAN Zhaoqi YAN Dakun SUN Simin li Mengzong ZHENG qiushi li Reserach Institute of Aero-Engine Beihang UniversityBeijing 100083China School of Energy and Power Engineering Beihang UniversityBeijing 100083China Key Laboratory of Fluid and Power Machinery Ministry of EducationXihua UniversityChengdu 610039China

Partial surge is a type of instability inception in transonic compressors and occurs in the form of axisymmetric low-frequency disturbances localized in the hub *** studies illustrate that the frequency of partial surge is set by the Helmholtz frequency of the entire system,which motivates to propose a hypothesis that the system response performs an important role in the formation of partial *** further verification,a series of experiments are conducted to explore the link between the propagating of the partial surge and the system feedback in this *** the first case,an additional test point is set on the wall of the plenum to detect the system *** the flow behaviors inside the plenum with the disturbances in the rotor tip and stator hub/tip regions,the effects of the system feedback on the occurrence of the continuous disturbances and the rotating stall cells are *** the second case,a screen is mounted at the compressor outlet to prevent positive feedback from the *** experimental results demonstrate that in the absence of system feedback,it is the occurrence of spike-type stall inception that leads to the flow instability instead of that of partial *** addition,three flow phenomena in the second case are discussed,including the occurrence of the single pulse,the unstable process during the stall evolution and the switch of instability inception.

关键词： Partial surge Plenum amplification Rotating stall System response Stall inception Transonic compressor

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Nanocomposites Facilitate the Removal of AβFibrils for Neuroprotection

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Chemical Research in Chinese Universities 2022年第2期38卷 522-528页

作者： CHAI Jingshan li qiushi ZHAO Yu liU Yang Key Laboratory of Functional Polymer Materials Ministry of EducationState Key Laboratory of Medicinal Chemical BiologyCollege of ChemistryNankai UniversityTianjin 300071P.R.China

Accumulation of β-amyloid(Aβ) fibrils in the brain is one of the main culprits in Alzheimer’s disease(AD) progression, which initiates the neuronal damage and subsequent neurodegeneration. Various anti-Aβ agents have shown the potentials to dissociate Aβ fibrils. However, these approaches can’t facilitate the removal of Aβ fibrils, resulting in a disappointing therapeutic effect. Herein, we demonstrate an integrated polymer nanocomposite(NP-GLVFF-IgG) that can dissociate Aβ fibrils into fragments and activate microglia to remove the fragments via Fc receptors-mediated phagocytosis. NP-GLVFF-IgG is constructed by an albumin/polymer hybrid nanoparticle with Gly-Leu-Val-Phe-Phe (GLVFF) peptides and Immunoglobulin G(IgG) molecules on the surface. In this design, NP-GLVFF-IgG achieves to dissociate the Aβ fibrils by the strong hydrogen-bonding interactions between Aβ fibrils and GLVFF peptides. Then, NP-GLVFF-IgG activates the microglial phagocytosis, thereby achieving an enhanced phagocytic removal of Aβ fibrils for neuroprotection. Moreover, NP-GLVFF-IgG achieves to trigger the effective removal of Aβ fibrils even under inflammatory condition that usually suppressed phagocytosis. Therefore, NP-GLVFF-IgG has great potential as a novel therapeutic platform for effective AD therapy.

关键词： Alzheimer’s disease Aβfibril Nanocomposite Hydrogen-bonding interaction Microglia

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Nanomedicine-based combination therapies for overcoming temozolomide resistance in glioblastomas

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Cancer Biology & Medicine 2023年第5期20卷 325-343页

作者： Chun Wang qiushi li Jian Xiao Yang liu State Key Laboratory of Medicinal Chemical Biology Nankai UniversityTianjin 300071China Key Laboratory of Functional Polymer Materials of Ministry of Education College of ChemistryNankai UniversityTianjin 300071China Frontiers Science Center for New Organic Matter Nankai UniversityTianjin 300071China

Glioblastoma(GBM)is the most common malignant brain *** current treatment strategies,including surgery,chemotherapy,and radiotherapy,have achieved clinical effects and prolonged the survival of patients,the gradual development of resistance against current therapies has led to a high recurrence rate and treatment *** underlying the development of resistance involve multiple factors,including drug efflux,DNA damage repair,glioma stem cells,and a hypoxic tumor environment,which are usually correlative and promote each *** many potential therapeutic targets have been discovered,combination therapy that regulates multiple resistance-related molecule pathways is considered an attractive *** recent years,nanomedicine has revolutionized cancer therapies with optimized accumulation,penetration,internalization,and controlled ***-brain barrier(BBB)penetration efficiency is also significantly improved through modifying ligands on nanomedicine and interacting with the receptors or transporters on the ***,different drugs for combination therapy usually process different pharmacokinetics and biodistribution,which can be further optimized with drug delivery systems to maximize the therapeutic efficiency of combination *** the current achievements in nanomedicine-based combination therapy for GBM are *** review aimed to provide a broader understanding of resistance mechanisms and nanomedicine-based combination therapies for future research on GBM treatment.

关键词： Combination therapy drug resistance glioblastoma nanotechnology temozolomide

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