Plasma jet has been widely used in supersonic combustor as an effective ignition and combustion assisted method,but currently it is mostly combined with the traditional wall fuel injection method,while the application...Plasma jet has been widely used in supersonic combustor as an effective ignition and combustion assisted method,but currently it is mostly combined with the traditional wall fuel injection method,while the application combined with the central fuel injection method is less.In order to expand the combustion range,the plasma jet was introduced into a strut-cavity combustor with an alternating-wedge.The effects of total pressure of strut fuel injection,total pressure of cavity fuel injection,total pressure of plasma jet injection and plasma jet media on the combustion characteristics were analyzed in supersonic flow by numerical calculations in a three-dimensional domain.The combustion field structure,wall pressure distribution,combustion efficiency and distribution of H2O at the exit of the combustor with different injection conditions were analyzed.The results show that the combustion efficiency decreases with the increase of the strut fuel injection total pressure.However,the combustion area downstream increases when the total pressure of the strut fuel injection increases within the proper range.The combustion range is expanded and the combustion efficiency is improved when the cavity fuel injection total pressure is increased within the range of 0.5−2.0 MPa,but a sharp drop in combustion efficiency can be found due to limited fuel mixing when the total injection pressure of the cavity fuel is excessively increased.With the increased total injection pressure of the plasma jet,the height of the cavity shear layer is raised and the equivalence ratio of the gas mixture in the cavity is improved.When the total pressure of the plasma jet is 1.25 MPa,the combustion efficiency reaches a maximum of 82.1%.The combustion-assisted effect of different plasma jet media is significantly different.When the medium of the plasma jet is O2,the combustion-assisted effect on the combustor is most significant.展开更多
We propose a new scheme to estimate the heating rate of trapped ions in thermal states. By applying a controlled-U gate between the internal and the motional states of one of the trapped ions, we could obtain the mean...We propose a new scheme to estimate the heating rate of trapped ions in thermal states. By applying a controlled-U gate between the internal and the motional states of one of the trapped ions, we could obtain the mean phonon number from the population of the internal state of the ion. The imperfection due to fluctuations of the relevant parameters in real experiments is considered and we anaiyze the experimental feasibility of our scheme with sophisticated ion trap techniques.展开更多
Radio waves are highly attenuated and distorted by turbulent plasma sheath around hypersonic vehicles in near space, leading to communication blackout. The purpose of the paper is to investigate the plasma channel cha...Radio waves are highly attenuated and distorted by turbulent plasma sheath around hypersonic vehicles in near space, leading to communication blackout. The purpose of the paper is to investigate the plasma channel characteristics and the communication performances over the channel. We treat the turbulent plasma medium as a fast fading wireless channel. The coherence time and the spectrum spread of the plasma sheath channel are obtained in terms of root-meansquare(RMS). Baseband simulation scheme is proposed based on a stratified model of the plasma flow field. Results indicate that the coherence time is on the order of milliseconds and decreases rapidly with the increasing electron density turbulence. The spectrum spread due to plasma turbulence is also significant. Extensive simulations have been carried out to make communication performance evaluations. Quantitative results show that error floor takes place for PSK and QAM, while FSK with noncoherent detection is a promising method to mitigate the blackout problem.展开更多
The speed of sound in quark matter is an important physical quantity for studying the properties and the spacetime evolution of quark-gluon plasma(QGP).The behavior of the speed of sound with respect to temperature an...The speed of sound in quark matter is an important physical quantity for studying the properties and the spacetime evolution of quark-gluon plasma(QGP).The behavior of the speed of sound with respect to temperature and density can reveal to some extent the equation of state and the phase structure of QGP.Building upon the previous studies on the speed of sound in symmetric quark matter,the formulae for calculating the speed of sound in asymmetric quark matter in the temperature-density space are further derived.The PNJL model is then used to calculate the dependence of the speed of sound on isospin asymmetry.Furthermore,the relationship between the magnitude of the speed of sound and the QCD phase structure is discussed,and the regions where the acoustic equation fails are indicated under different physical conditions.It is found that the boundary of vanishing sound speed in asymmetric quark matter is smaller than that in symmetric quark matter,meaning that the range where the acoustic wave equation fails in asymmetric quark matter is smaller than that in symmetric quark matter.The results also indicate that in most of the stable phase,the speed of sound in asymmetric quark matter is slightly larger than that in symmetric quark matter.展开更多
The basic set of fluid equations can be reduced to the nonlinear Kortewege-de Vries(KdV)and nonlinear Schro¨dinger(NLS)equations.The rational solutions for the two equations has been obtained.The exact amplitude ...The basic set of fluid equations can be reduced to the nonlinear Kortewege-de Vries(KdV)and nonlinear Schro¨dinger(NLS)equations.The rational solutions for the two equations has been obtained.The exact amplitude of the nonlinear ion-acoustic solitary wave can be obtained directly without resorting to any successive approximation techniques by a direct analysis of the given field equations.The Sagdeev’s potential is obtained in terms of ion acoustic velocity by simply solving an algebraic equation.The soliton and double layer solutions are obtained as a small amplitude approximation.A comparison between the exact soliton solution and that obtained from the reductive perturbation theory are also discussed.展开更多
基金Project(51606220)supported by the National Natural Science Foundation of ChinaProject(1194028)supported by the Beijing Natural Science Foundation,China。
文摘Plasma jet has been widely used in supersonic combustor as an effective ignition and combustion assisted method,but currently it is mostly combined with the traditional wall fuel injection method,while the application combined with the central fuel injection method is less.In order to expand the combustion range,the plasma jet was introduced into a strut-cavity combustor with an alternating-wedge.The effects of total pressure of strut fuel injection,total pressure of cavity fuel injection,total pressure of plasma jet injection and plasma jet media on the combustion characteristics were analyzed in supersonic flow by numerical calculations in a three-dimensional domain.The combustion field structure,wall pressure distribution,combustion efficiency and distribution of H2O at the exit of the combustor with different injection conditions were analyzed.The results show that the combustion efficiency decreases with the increase of the strut fuel injection total pressure.However,the combustion area downstream increases when the total pressure of the strut fuel injection increases within the proper range.The combustion range is expanded and the combustion efficiency is improved when the cavity fuel injection total pressure is increased within the range of 0.5−2.0 MPa,but a sharp drop in combustion efficiency can be found due to limited fuel mixing when the total injection pressure of the cavity fuel is excessively increased.With the increased total injection pressure of the plasma jet,the height of the cavity shear layer is raised and the equivalence ratio of the gas mixture in the cavity is improved.When the total pressure of the plasma jet is 1.25 MPa,the combustion efficiency reaches a maximum of 82.1%.The combustion-assisted effect of different plasma jet media is significantly different.When the medium of the plasma jet is O2,the combustion-assisted effect on the combustor is most significant.
基金Supported by National Natural Science Foundation of China under Grant No.10774163
文摘We propose a new scheme to estimate the heating rate of trapped ions in thermal states. By applying a controlled-U gate between the internal and the motional states of one of the trapped ions, we could obtain the mean phonon number from the population of the internal state of the ion. The imperfection due to fluctuations of the relevant parameters in real experiments is considered and we anaiyze the experimental feasibility of our scheme with sophisticated ion trap techniques.
基金supported by the National Key Basic Research Program of China(2014CB340206)partly supported by National Natural Science Foundation of China(No.61132002,No.61321061)
文摘Radio waves are highly attenuated and distorted by turbulent plasma sheath around hypersonic vehicles in near space, leading to communication blackout. The purpose of the paper is to investigate the plasma channel characteristics and the communication performances over the channel. We treat the turbulent plasma medium as a fast fading wireless channel. The coherence time and the spectrum spread of the plasma sheath channel are obtained in terms of root-meansquare(RMS). Baseband simulation scheme is proposed based on a stratified model of the plasma flow field. Results indicate that the coherence time is on the order of milliseconds and decreases rapidly with the increasing electron density turbulence. The spectrum spread due to plasma turbulence is also significant. Extensive simulations have been carried out to make communication performance evaluations. Quantitative results show that error floor takes place for PSK and QAM, while FSK with noncoherent detection is a promising method to mitigate the blackout problem.
文摘The speed of sound in quark matter is an important physical quantity for studying the properties and the spacetime evolution of quark-gluon plasma(QGP).The behavior of the speed of sound with respect to temperature and density can reveal to some extent the equation of state and the phase structure of QGP.Building upon the previous studies on the speed of sound in symmetric quark matter,the formulae for calculating the speed of sound in asymmetric quark matter in the temperature-density space are further derived.The PNJL model is then used to calculate the dependence of the speed of sound on isospin asymmetry.Furthermore,the relationship between the magnitude of the speed of sound and the QCD phase structure is discussed,and the regions where the acoustic equation fails are indicated under different physical conditions.It is found that the boundary of vanishing sound speed in asymmetric quark matter is smaller than that in symmetric quark matter,meaning that the range where the acoustic wave equation fails in asymmetric quark matter is smaller than that in symmetric quark matter.The results also indicate that in most of the stable phase,the speed of sound in asymmetric quark matter is slightly larger than that in symmetric quark matter.
基金Supported by the Deanship of Scientific Research in Salman Bin Abdul-Aziz University,Saudi Arabia under Grant No.104/T/33
文摘The basic set of fluid equations can be reduced to the nonlinear Kortewege-de Vries(KdV)and nonlinear Schro¨dinger(NLS)equations.The rational solutions for the two equations has been obtained.The exact amplitude of the nonlinear ion-acoustic solitary wave can be obtained directly without resorting to any successive approximation techniques by a direct analysis of the given field equations.The Sagdeev’s potential is obtained in terms of ion acoustic velocity by simply solving an algebraic equation.The soliton and double layer solutions are obtained as a small amplitude approximation.A comparison between the exact soliton solution and that obtained from the reductive perturbation theory are also discussed.
