With the aim of deepening the understanding of high-speed compressor cascade flow,this paper reports an experimental study on NACA-65 K48 compressor cascade with high subsonic inlet flow.With the increase of passage p...With the aim of deepening the understanding of high-speed compressor cascade flow,this paper reports an experimental study on NACA-65 K48 compressor cascade with high subsonic inlet flow.With the increase of passage pressurizing ability, endwall boundary layer behavior is deteriorated, and the transition zone is extended from suction surface to the endwall as the adverse pressure gradient increases.Cross flow from endwall to midspan, mixing of corner boundary layer and the main stream, and reversal flow on the suction surface are caused by corner separation vortex structures.Passage vortex is the main corner separation vortex.During its movement downstream, the size grows bigger while the rotating direction changes, forming a limiting circle.With higher incidence, corner separation is further deteriorated, leading to higher flow loss.Meanwhile, corner separation structure, flow mixing characteristics and flow loss distribution vary a lot with the change of incidence.Compared with low aspect-ratio model, corner separation of high aspect-ratio model moves away from the endwall and is more sufficiently developed downstream the cascade.Results obtained present details of high-speed compressor cascade flow,which is rare in the relating research fields and is beneficial to mechanism analysis, aerodynamic optimization and flow control design.展开更多
The turbulence characteristics of both decelerating and accelerating flows under a gradually varying flume are investigated by using a three-dimensional down-looking acoustic Doppler velocimeter （ADV）. The time-aver...The turbulence characteristics of both decelerating and accelerating flows under a gradually varying flume are investigated by using a three-dimensional down-looking acoustic Doppler velocimeter （ADV）. The time-averaged velocity profiles are flatened except for the central parts, and fairly fit into logarithmic laws and those in the plane circulation under the gradual expansion are more likely to be negative. The complex secondary currents are identified under the present gradual transition attributed to the combination of driving forces induced by both the boundary configuration variation and the tmbalanced turbulence： a circulation on each side of the expansion and a pair of circulations on each side of the contraction. One sees an anisotropy in the turbulence intensities, the turbulence intensities increase or level out with the flow depth except those under expansion, and the V component of the turbulence intensity typically outweighs that in the streamwise direction. Apart from the above results, the respective particular distributions of the primary Reynolds shear stresses （ rxy and rxz ） under the gradual expansion and contraction can account for the patterns of the secondary currents in this investigation.展开更多
A model is proposed for liquid film profile prediction in gas-liquid two-phase flow,which is able to provide the film thickness along the circumferential direction and the pressure gradient in the flow direction.A two...A model is proposed for liquid film profile prediction in gas-liquid two-phase flow,which is able to provide the film thickness along the circumferential direction and the pressure gradient in the flow direction.A two-fluid model is used to calculate both gas and liquid phases’flow characteristics.The secondary flow occurring in the gas phase is taken into account and a sailing boat mechanism is introduced.Moreover,energy conservation is applied for obtaining the liquid film thickness distribution along the circumference.Liquid film thickness distribution is calculated accordingly for different cases;its values are compared with other models and available experimental data.As a result,the newly proposed model is tested and good performances are demonstrated.The liquid film thickness distribution in small pipes and inclined pipes is also studied,and regime transition is revealed by liquid film profile evolution.The observed inflection point demonstrates that the liquid film thickness decreases steeply along the circumference,when the circle angle ranges between 30°and 50°for gas-liquid stratified flow with small superficial velocities.展开更多
The process through which a laminar flow undergoes transition to turbulence is of great fundamental and practical interest. Such a process is hugely complex as there are many diverse routes for a laminar flow to becom...The process through which a laminar flow undergoes transition to turbulence is of great fundamental and practical interest. Such a process is hugely complex as there are many diverse routes for a laminar flow to become turbulent flow. The transition process is usually initiated by flow instabilities—a primary instability stage followed by a secondary instability stage. This forms a rational framework for the early stage of a transition process and it is crucially important to understand the physics of instabilities leading to turbulence. This article reviews the results of studies on secondary instability of separated shear layers in separation bubbles and summaries the current status of our understanding in this area.展开更多
Fibroblast growth factor receptors(FGFRs)play an important role in the regulation of cell proliferation,migration and differentiation,while the juxtamembrane domain(JMD)of FGFRs is the key in mediating these transmemb...Fibroblast growth factor receptors(FGFRs)play an important role in the regulation of cell proliferation,migration and differentiation,while the juxtamembrane domain(JMD)of FGFRs is the key in mediating these transmembrane signal transduction processes.Here,we expressed and purified the JMD(398K-470R)of FGFR1 with the presence of transmembrane domain(377I-397Y).The results from nuclear magnetic resonance(NMR)chemical shift analysis demonstrate that the main structure of JMD is disordered.Yet,the N-terminus of JMD was observed to form a short a-helix upon introducing negatively charged lipid 1,2-dioleoyl-sn-glycero-3-phospho-L-serine(DOPS)into its membrane mimic bicelles.Moreover,the N-terminus of JMD interacts with FRS2a,which is a substrate 2a of FGFR.Hence,we propose a model that FGFR1-JMD may interact with FRS2a and negatively charged lipids competitively.Our study provides a new understanding on the role of the JMD of FGFRs.展开更多
基金supported by the National Natural Science Foundation of China (Nos.51336011, 50906100)the Science Foundation for the Author of National Excellent Doctoral Dissertation of China (No.201172)China Scholarship Council
文摘With the aim of deepening the understanding of high-speed compressor cascade flow,this paper reports an experimental study on NACA-65 K48 compressor cascade with high subsonic inlet flow.With the increase of passage pressurizing ability, endwall boundary layer behavior is deteriorated, and the transition zone is extended from suction surface to the endwall as the adverse pressure gradient increases.Cross flow from endwall to midspan, mixing of corner boundary layer and the main stream, and reversal flow on the suction surface are caused by corner separation vortex structures.Passage vortex is the main corner separation vortex.During its movement downstream, the size grows bigger while the rotating direction changes, forming a limiting circle.With higher incidence, corner separation is further deteriorated, leading to higher flow loss.Meanwhile, corner separation structure, flow mixing characteristics and flow loss distribution vary a lot with the change of incidence.Compared with low aspect-ratio model, corner separation of high aspect-ratio model moves away from the endwall and is more sufficiently developed downstream the cascade.Results obtained present details of high-speed compressor cascade flow,which is rare in the relating research fields and is beneficial to mechanism analysis, aerodynamic optimization and flow control design.
基金supported by the National Natural Science Foundation of China(Grant No.41171016)the Sichuan Province Science and Technology Support Program(Grant No.2014SZ0163)
文摘The turbulence characteristics of both decelerating and accelerating flows under a gradually varying flume are investigated by using a three-dimensional down-looking acoustic Doppler velocimeter （ADV）. The time-averaged velocity profiles are flatened except for the central parts, and fairly fit into logarithmic laws and those in the plane circulation under the gradual expansion are more likely to be negative. The complex secondary currents are identified under the present gradual transition attributed to the combination of driving forces induced by both the boundary configuration variation and the tmbalanced turbulence： a circulation on each side of the expansion and a pair of circulations on each side of the contraction. One sees an anisotropy in the turbulence intensities, the turbulence intensities increase or level out with the flow depth except those under expansion, and the V component of the turbulence intensity typically outweighs that in the streamwise direction. Apart from the above results, the respective particular distributions of the primary Reynolds shear stresses （ rxy and rxz ） under the gradual expansion and contraction can account for the patterns of the secondary currents in this investigation.
基金support provided by Shandong Provincial Science and Technology Plan Project(No.2023TSGC0625)Natural Resources Defense Council(NRDC,K94).
文摘A model is proposed for liquid film profile prediction in gas-liquid two-phase flow,which is able to provide the film thickness along the circumferential direction and the pressure gradient in the flow direction.A two-fluid model is used to calculate both gas and liquid phases’flow characteristics.The secondary flow occurring in the gas phase is taken into account and a sailing boat mechanism is introduced.Moreover,energy conservation is applied for obtaining the liquid film thickness distribution along the circumference.Liquid film thickness distribution is calculated accordingly for different cases;its values are compared with other models and available experimental data.As a result,the newly proposed model is tested and good performances are demonstrated.The liquid film thickness distribution in small pipes and inclined pipes is also studied,and regime transition is revealed by liquid film profile evolution.The observed inflection point demonstrates that the liquid film thickness decreases steeply along the circumference,when the circle angle ranges between 30°and 50°for gas-liquid stratified flow with small superficial velocities.
文摘The process through which a laminar flow undergoes transition to turbulence is of great fundamental and practical interest. Such a process is hugely complex as there are many diverse routes for a laminar flow to become turbulent flow. The transition process is usually initiated by flow instabilities—a primary instability stage followed by a secondary instability stage. This forms a rational framework for the early stage of a transition process and it is crucially important to understand the physics of instabilities leading to turbulence. This article reviews the results of studies on secondary instability of separated shear layers in separation bubbles and summaries the current status of our understanding in this area.
基金Special Foundation of President of the Chinese Academy of Sciences(Grant No.,YZJJ2021QN33,YZJJ2020QN27)Collaborative Innovation Program of Hefei Science Center,CAS(2020HSC-CIP008).
文摘Fibroblast growth factor receptors(FGFRs)play an important role in the regulation of cell proliferation,migration and differentiation,while the juxtamembrane domain(JMD)of FGFRs is the key in mediating these transmembrane signal transduction processes.Here,we expressed and purified the JMD(398K-470R)of FGFR1 with the presence of transmembrane domain(377I-397Y).The results from nuclear magnetic resonance(NMR)chemical shift analysis demonstrate that the main structure of JMD is disordered.Yet,the N-terminus of JMD was observed to form a short a-helix upon introducing negatively charged lipid 1,2-dioleoyl-sn-glycero-3-phospho-L-serine(DOPS)into its membrane mimic bicelles.Moreover,the N-terminus of JMD interacts with FRS2a,which is a substrate 2a of FGFR.Hence,we propose a model that FGFR1-JMD may interact with FRS2a and negatively charged lipids competitively.Our study provides a new understanding on the role of the JMD of FGFRs.
