The Circular Electron Positron Collider(CEPC)is a large scientific project initiated and hosted by China,fostered through extensive collaboration with international partners.The complex comprises four accelerators:a 3...The Circular Electron Positron Collider(CEPC)is a large scientific project initiated and hosted by China,fostered through extensive collaboration with international partners.The complex comprises four accelerators:a 30 GeV Linac,a 1.1 GeV Damping Ring,a Booster capable of achieving energies up to 180 GeV,and a Collider operating at varying energy modes(Z,W,H,and tt).The Linac and Damping Ring are situated on the surface,while the subterranean Booster and Collider are housed in a 100 km circumference underground tunnel,strategically accommodating future expansion with provisions for a potential Super Proton Proton Collider(SPPC).The CEPC primarily serves as a Higgs factory.In its baseline design with synchrotron radiation(SR)power of 30 MW per beam,it can achieve a luminosity of 5×10^(34)cm^(-2)s^(-1)per interaction point(IP),resulting in an integrated luminosity of 13 ab^(-1)for two IPs over a decade,producing 2.6 million Higgs bosons.Increasing the SR power to 50 MW per beam expands the CEPC's capability to generate 4.3 million Higgs bosons,facilitating precise measurements of Higgs coupling at sub-percent levels,exceeding the precision expected from the HL-LHC by an order of magnitude.This Technical Design Report(TDR)follows the Preliminary Conceptual Design Report(Pre-CDR,2015)and the Conceptual Design Report(CDR,2018),comprehensively detailing the machine's layout,performance metrics,physical design and analysis,technical systems design,R&D and prototyping efforts,and associated civil engineering aspects.Additionally,it includes a cost estimate and a preliminary construction timeline,establishing a framework for forthcoming engineering design phase and site selection procedures.Construction is anticipated to begin around 2027-2028,pending government approval,with an estimated duration of 8 years.The commencement of experiments and data collection could potentially be initiated in the mid-2030s.展开更多
A turbine based combined cycle(TBCC)propulsion system uses a turbine-based engine to accelerate the vehicle from takeoff to the mode transition flight condition,at which point,the propulsion system performs a“mode tr...A turbine based combined cycle(TBCC)propulsion system uses a turbine-based engine to accelerate the vehicle from takeoff to the mode transition flight condition,at which point,the propulsion system performs a“mode transition”from the turbine to ramjet engine.Smooth inlet mode transition is accomplished when flow is diverted from one flowpath to the other,without experiencing unstart or buzz.The smooth inlet mode transition is a complex unsteady process and it is one of the enabling technologies for combined cycle engine to become a functional reality.In order to unveil the unsteady process of inlet mode transition,the research of over/under TBCC inlet mode transition was conducted through a numerical simulation.It shows that during the mode transition the terminal shock oscillates in the inlet.During the process of inlet mode transition mass flow rate and Mach number of turbojet flowpath reduce with oscillation.While in ramjet flowpath the flow field is non-uniform at the beginning of inlet mode transition.The speed of mode transition and the operation states of the turbojet and ramjet engines will affect the motion of terminal shock.The result obtained in present paper can help us realize the unsteady flow characteristic during the mode transition and provide some suggestions for TBCC inlet mode transition based on the smooth transition of thrust.展开更多
The characteristics of unsteady flow in a dual-flowpath inlet, which was designed for a Turbine Based Combined Cycle（TBCC） propulsion system, and the control methods of unsteady flow were investigated experimentally...The characteristics of unsteady flow in a dual-flowpath inlet, which was designed for a Turbine Based Combined Cycle（TBCC） propulsion system, and the control methods of unsteady flow were investigated experimentally and numerically. It was characterized by large-amplitude pressure oscillations and traveling shock waves. As the inlet operated in supercritical condition,namely the terminal shock located in the throat, the shock oscillated, and the period of oscillation was about 50 ms, while the amplitude was 6 mm. The shock oscillation was caused by separation in the diffuser. This shock oscillation can be controlled by extending the length of diffuser which reduces pressure gradient along the flowpath. As the inlet operated in critical condition, namely the terminal shock located at the shoulder of the third compression ramp, the shock oscillated,and the period of oscillation was about 7.5 ms, while the amplitude was 12 mm. At this condition,the shock oscillation was caused by an incompatible backpressure in the bleed region. It can be controlled by increasing the backpressure of the bleed region.展开更多
A bump is typically used in the inlet system of an aircraft engine to compress the incoming airflow and to reduce boundary layer thickness developed over fuselage.In this work,the turbulent flow over a three-dimension...A bump is typically used in the inlet system of an aircraft engine to compress the incoming airflow and to reduce boundary layer thickness developed over fuselage.In this work,the turbulent flow over a three-dimensional bump is experimentally studied.The bump model is mounted in a closed return wind tunnel operated at the nominal velocity 10 m/s,corresponding to a friction Reynolds number of 2300.The flow field upstream the bump,along the bump centerline and at two different spanwise planes is measured with Particle Image Velocimetry(PIV).It is observed that a favorable pressure gradient develops until the suction peak of the bump,and that the average turbulence intensity within boundary layer is attenuated due to this favorable pressure gradient.The boundary layer thickness identified by examining profiles of streamwise velocity decreases significantly along the bump.The wall-normal position of the Turbulent/Non-Turbulent Interface(TNTI)identified with the vorticity criterion is also observed to decrease along the bump.When studying the behavior of the boundary layer thickness at different spanwise positions,we found that it tends to be larger in planes away from the centreline,which suggests that the bump diverts the flow.展开更多
基金support from diverse funding sources,including the National Key Program for S&T Research and Development of the Ministry of Science and Technology(MOST),Yifang Wang's Science Studio of the Ten Thousand Talents Project,the CAS Key Foreign Cooperation Grant,the National Natural Science Foundation of China(NSFC)Beijing Municipal Science&Technology Commission,the CAS Focused Science Grant,the IHEP Innovation Grant,the CAS Lead Special Training Programthe CAS Center for Excellence in Particle Physics,the CAS International Partnership Program,and the CAS/SAFEA International Partnership Program for Creative Research Teams.
文摘The Circular Electron Positron Collider(CEPC)is a large scientific project initiated and hosted by China,fostered through extensive collaboration with international partners.The complex comprises four accelerators:a 30 GeV Linac,a 1.1 GeV Damping Ring,a Booster capable of achieving energies up to 180 GeV,and a Collider operating at varying energy modes(Z,W,H,and tt).The Linac and Damping Ring are situated on the surface,while the subterranean Booster and Collider are housed in a 100 km circumference underground tunnel,strategically accommodating future expansion with provisions for a potential Super Proton Proton Collider(SPPC).The CEPC primarily serves as a Higgs factory.In its baseline design with synchrotron radiation(SR)power of 30 MW per beam,it can achieve a luminosity of 5×10^(34)cm^(-2)s^(-1)per interaction point(IP),resulting in an integrated luminosity of 13 ab^(-1)for two IPs over a decade,producing 2.6 million Higgs bosons.Increasing the SR power to 50 MW per beam expands the CEPC's capability to generate 4.3 million Higgs bosons,facilitating precise measurements of Higgs coupling at sub-percent levels,exceeding the precision expected from the HL-LHC by an order of magnitude.This Technical Design Report(TDR)follows the Preliminary Conceptual Design Report(Pre-CDR,2015)and the Conceptual Design Report(CDR,2018),comprehensively detailing the machine's layout,performance metrics,physical design and analysis,technical systems design,R&D and prototyping efforts,and associated civil engineering aspects.Additionally,it includes a cost estimate and a preliminary construction timeline,establishing a framework for forthcoming engineering design phase and site selection procedures.Construction is anticipated to begin around 2027-2028,pending government approval,with an estimated duration of 8 years.The commencement of experiments and data collection could potentially be initiated in the mid-2030s.
基金The authors gratefully acknowledge the financial support received from the Aviation Foundation Project(Grant No.2012ZB52031)the Fundamental Research Funds for the Central Universities(Grant No.NJ20140021)for this project.
文摘A turbine based combined cycle(TBCC)propulsion system uses a turbine-based engine to accelerate the vehicle from takeoff to the mode transition flight condition,at which point,the propulsion system performs a“mode transition”from the turbine to ramjet engine.Smooth inlet mode transition is accomplished when flow is diverted from one flowpath to the other,without experiencing unstart or buzz.The smooth inlet mode transition is a complex unsteady process and it is one of the enabling technologies for combined cycle engine to become a functional reality.In order to unveil the unsteady process of inlet mode transition,the research of over/under TBCC inlet mode transition was conducted through a numerical simulation.It shows that during the mode transition the terminal shock oscillates in the inlet.During the process of inlet mode transition mass flow rate and Mach number of turbojet flowpath reduce with oscillation.While in ramjet flowpath the flow field is non-uniform at the beginning of inlet mode transition.The speed of mode transition and the operation states of the turbojet and ramjet engines will affect the motion of terminal shock.The result obtained in present paper can help us realize the unsteady flow characteristic during the mode transition and provide some suggestions for TBCC inlet mode transition based on the smooth transition of thrust.
基金co-supported by the Funding for Outstanding Doctoral Dissertation in NUAA of China(No.BCXJ16-01)Funding of Jiangsu Innovation Program for Graduate Education(No.KYLX16_0393)+2 种基金Foundation of Graduate Innovation Center in NUAA of China(No.KFJJ20160204)the Fundamental Research Funds for the Central Universities and the Aerospace ScienceTechnology Innovation Fund of China Aerospace Science and Technology Corporation
文摘The characteristics of unsteady flow in a dual-flowpath inlet, which was designed for a Turbine Based Combined Cycle（TBCC） propulsion system, and the control methods of unsteady flow were investigated experimentally and numerically. It was characterized by large-amplitude pressure oscillations and traveling shock waves. As the inlet operated in supercritical condition,namely the terminal shock located in the throat, the shock oscillated, and the period of oscillation was about 50 ms, while the amplitude was 6 mm. The shock oscillation was caused by separation in the diffuser. This shock oscillation can be controlled by extending the length of diffuser which reduces pressure gradient along the flowpath. As the inlet operated in critical condition, namely the terminal shock located at the shoulder of the third compression ramp, the shock oscillated,and the period of oscillation was about 7.5 ms, while the amplitude was 12 mm. At this condition,the shock oscillation was caused by an incompatible backpressure in the bleed region. It can be controlled by increasing the backpressure of the bleed region.
基金China Scholarship Council for providing the financial supportthe financial support and the National Natural Science Foundation of China(No.11772155)。
文摘A bump is typically used in the inlet system of an aircraft engine to compress the incoming airflow and to reduce boundary layer thickness developed over fuselage.In this work,the turbulent flow over a three-dimensional bump is experimentally studied.The bump model is mounted in a closed return wind tunnel operated at the nominal velocity 10 m/s,corresponding to a friction Reynolds number of 2300.The flow field upstream the bump,along the bump centerline and at two different spanwise planes is measured with Particle Image Velocimetry(PIV).It is observed that a favorable pressure gradient develops until the suction peak of the bump,and that the average turbulence intensity within boundary layer is attenuated due to this favorable pressure gradient.The boundary layer thickness identified by examining profiles of streamwise velocity decreases significantly along the bump.The wall-normal position of the Turbulent/Non-Turbulent Interface(TNTI)identified with the vorticity criterion is also observed to decrease along the bump.When studying the behavior of the boundary layer thickness at different spanwise positions,we found that it tends to be larger in planes away from the centreline,which suggests that the bump diverts the flow.
