As a key part of the pyrotechnic gas generator,the filter not only removes the particulate matter but also cools the hot gas to a safe level.This paper aims to improve the understanding of the basic heat and flow phen...As a key part of the pyrotechnic gas generator,the filter not only removes the particulate matter but also cools the hot gas to a safe level.This paper aims to improve the understanding of the basic heat and flow phenomenon in the gas generator.The pyrotechnic gas generator is modelling by a simplified filter structure with fiber arrays.A finite-volume model of the heat and fluid flow is proposed to simulate the detailed multi-dimensional flow and energy conversion behaviors.Several verification results are in good agreement with data in different references.Simulation results demonstrate that the filter can not only absorb heat from the gas but also cause the high intensity enhancement of the heat transfer.The performance difference between inline and staggered arrays is also discussed.The findings of the study put a further prediction tool for the understanding and design of the filter system with fibers.展开更多
The rotor initial unbalance of an aeroengine gas generator of turboshaft engine seriously affects rotor assembly process.To reasonably optimize rotor assembly process,the effect analyses of rotor initial unbalance of ...The rotor initial unbalance of an aeroengine gas generator of turboshaft engine seriously affects rotor assembly process.To reasonably optimize rotor assembly process,the effect analyses of rotor initial unbalance of single disc and combined discs on rotor dynamic characteristics are firstly implemented in respect of the dispersity of rotor initial unbalance.It is found that the most important factors contributing to rotor vibration are the unbalances of the first stage compressor disc and the second stage turbine disc.However,reducing the mass of two discs conflicts with the control of the whole gas generator rotor balance resulting from the unbalance increase of single components.Thus,we further analyze the key control factors of affecting rotor initial unbalance,and give the strict control measures of centrifugal impeller runout in the assembly process by adjusting the angle of central tie rod axis.The purpose of this measures to make the assembly process simpler and more effective for timely controlling rotor initial unbalance.The efforts of this study validate that the proposed method is workable for the rotor tightened by a central tie rod and possesses the significant meaning of practical application in engineering.展开更多
With the vigorous promotion of energy conservation and implementation of clean energy strategies,China＇s natural gas industry has entered a rapid development phase,and natural gas is playing an increasingly important...With the vigorous promotion of energy conservation and implementation of clean energy strategies,China＇s natural gas industry has entered a rapid development phase,and natural gas is playing an increasingly important role in China＇s energy structure.This paper uses a Generalized Weng model to forecast Chinese regional natural gas production,where accuracy and reasonableness compared with other predictions are enhanced by taking remaining estimated recoverable resources as a criterion.The forecast shows that China＇s natural gas production will maintain a rapid growth with peak gas of 323 billion cubic meters a year coming in 2036;in 2020,natural gas production will surpass that of oil to become a more important source of energy.Natural gas will play an important role in optimizing China＇s energy consumption structure and will be a strategic replacement of oil.This will require that exploration and development of conventional natural gas is highly valued and its industrial development to be reasonably planned.As well,full use should be made of domestic and international markets.Initiative should also be taken in the exploration and development of unconventional and deepwater gas,which shall form a complement to the development of China＇s conventional natural gas industry.展开更多
The Sandage Loeb （SL） test is a direct measurement of the cosmic expansion by probing the redshift drifts of quasi-stellar objects in the ＇redshift desert＇ of 2 〈 z 〈 5. In this work, we investigate its constrai...The Sandage Loeb （SL） test is a direct measurement of the cosmic expansion by probing the redshift drifts of quasi-stellar objects in the ＇redshift desert＇ of 2 〈 z 〈 5. In this work, we investigate its constraints on the unified dark energy and dark matter models including the generalized Chaplygin gas and the superfluid Chaplygin gas. In addition, type Ia supernovae （SNIa） data and the distance ratios derived from the cosmic microwave background radiation and baryon acoustic oscillation observations （CMB/BAO） are also used. We find that the mock SL data gives the tightest constraints on the model parameters and it can help to reduce the parameter regions allowed by the present SNIa＋CMB/BAO by about 75% when all datasets considered are combined. Thus the SL test is a worthy and long awaited measurement to probe effectively the cosmic expanding history and the properties of dark energy.展开更多
Using recently observed data： the Constitution dataset of type supernovae Ia （SNIa）, the observational Hubble data （OHD）, the measurement results of baryon acoustic oscillation （BAO） from the Sloan Digital Sky ...Using recently observed data： the Constitution dataset of type supernovae Ia （SNIa）, the observational Hubble data （OHD）, the measurement results of baryon acoustic oscillation （BAO） from the Sloan Digital Sky Survey （SDSS） and the Two Degree Field Galaxy Redshift Survey （2dFGRS）, and the current cosmic microwave background （CMB） data from the five-year Wilkinson Microwave Anisotropy Probe （WMAP）, we apply the Markov Chain Monte Carlo method to investigate the observational constraints on the generalized Chaplygin gas （GCG） model as the unification of dark matter and dark energy. For this unified model, the constraints on GCG mixture are discussed by considering the different expressions of current matter density or considering constraints as being independent of the matter quantity Ωm.展开更多
基金This work is supported by the National Natural Science Foundation of China(Grant No.11972194)the Fundamental Research Funds for the Central Universities,No.30918011323China Postdoctoral Science Foundation funded project(Grant No.2015M581797).
文摘As a key part of the pyrotechnic gas generator,the filter not only removes the particulate matter but also cools the hot gas to a safe level.This paper aims to improve the understanding of the basic heat and flow phenomenon in the gas generator.The pyrotechnic gas generator is modelling by a simplified filter structure with fiber arrays.A finite-volume model of the heat and fluid flow is proposed to simulate the detailed multi-dimensional flow and energy conversion behaviors.Several verification results are in good agreement with data in different references.Simulation results demonstrate that the filter can not only absorb heat from the gas but also cause the high intensity enhancement of the heat transfer.The performance difference between inline and staggered arrays is also discussed.The findings of the study put a further prediction tool for the understanding and design of the filter system with fibers.
文摘The rotor initial unbalance of an aeroengine gas generator of turboshaft engine seriously affects rotor assembly process.To reasonably optimize rotor assembly process,the effect analyses of rotor initial unbalance of single disc and combined discs on rotor dynamic characteristics are firstly implemented in respect of the dispersity of rotor initial unbalance.It is found that the most important factors contributing to rotor vibration are the unbalances of the first stage compressor disc and the second stage turbine disc.However,reducing the mass of two discs conflicts with the control of the whole gas generator rotor balance resulting from the unbalance increase of single components.Thus,we further analyze the key control factors of affecting rotor initial unbalance,and give the strict control measures of centrifugal impeller runout in the assembly process by adjusting the angle of central tie rod axis.The purpose of this measures to make the assembly process simpler and more effective for timely controlling rotor initial unbalance.The efforts of this study validate that the proposed method is workable for the rotor tightened by a central tie rod and possesses the significant meaning of practical application in engineering.
基金the National Social Science Funds of China (13&ZD159)the National Natural Science Foundation of China (71303258, 71373285)+1 种基金MOE (Ministry of Education in China) Project of Humanities and Social Sciences (13YJC630148)Science Foundation of China University of Petroleum, Beijing (ZX20150130) for sponsoring this joint research
文摘With the vigorous promotion of energy conservation and implementation of clean energy strategies,China＇s natural gas industry has entered a rapid development phase,and natural gas is playing an increasingly important role in China＇s energy structure.This paper uses a Generalized Weng model to forecast Chinese regional natural gas production,where accuracy and reasonableness compared with other predictions are enhanced by taking remaining estimated recoverable resources as a criterion.The forecast shows that China＇s natural gas production will maintain a rapid growth with peak gas of 323 billion cubic meters a year coming in 2036;in 2020,natural gas production will surpass that of oil to become a more important source of energy.Natural gas will play an important role in optimizing China＇s energy consumption structure and will be a strategic replacement of oil.This will require that exploration and development of conventional natural gas is highly valued and its industrial development to be reasonably planned.As well,full use should be made of domestic and international markets.Initiative should also be taken in the exploration and development of unconventional and deepwater gas,which shall form a complement to the development of China＇s conventional natural gas industry.
基金Supported by the National Natural Science Foundation of China under Grants Nos 11175093,11222545,11435006,and 11375092the Specialized Research Fund for the Doctoral Program of Higher Education under Grant No 20124306110001the K.C.Wong Magna Fund of Ningbo University
文摘The Sandage Loeb （SL） test is a direct measurement of the cosmic expansion by probing the redshift drifts of quasi-stellar objects in the ＇redshift desert＇ of 2 〈 z 〈 5. In this work, we investigate its constraints on the unified dark energy and dark matter models including the generalized Chaplygin gas and the superfluid Chaplygin gas. In addition, type Ia supernovae （SNIa） data and the distance ratios derived from the cosmic microwave background radiation and baryon acoustic oscillation observations （CMB/BAO） are also used. We find that the mock SL data gives the tightest constraints on the model parameters and it can help to reduce the parameter regions allowed by the present SNIa＋CMB/BAO by about 75% when all datasets considered are combined. Thus the SL test is a worthy and long awaited measurement to probe effectively the cosmic expanding history and the properties of dark energy.
基金Project supported by the National Natural Science Foundation of China (Grant Nos.10875056 and 10703001)the Specialized Research Fund for the Doctoral Program of Higher Education of China (Grant No.20070141034)
文摘Using recently observed data： the Constitution dataset of type supernovae Ia （SNIa）, the observational Hubble data （OHD）, the measurement results of baryon acoustic oscillation （BAO） from the Sloan Digital Sky Survey （SDSS） and the Two Degree Field Galaxy Redshift Survey （2dFGRS）, and the current cosmic microwave background （CMB） data from the five-year Wilkinson Microwave Anisotropy Probe （WMAP）, we apply the Markov Chain Monte Carlo method to investigate the observational constraints on the generalized Chaplygin gas （GCG） model as the unification of dark matter and dark energy. For this unified model, the constraints on GCG mixture are discussed by considering the different expressions of current matter density or considering constraints as being independent of the matter quantity Ωm.
