The transition from a deflagration to a detonation (DDT) in gas dynamics is investigated through the process of a deflagration with a imite width flame overtaken by a shock. The problem is formulated as a free boundar...The transition from a deflagration to a detonation (DDT) in gas dynamics is investigated through the process of a deflagration with a imite width flame overtaken by a shock. The problem is formulated as a free boundary value problem in an angular domain with a strong detonation and a reflected shock as boundaries. The main difficulty lies in the fact that the strength of reflected shock is zero at the vertex where the shock speed degenerates to be the same as the characteristic speed. The conclusion is that a strong detonation and a retonation (a reflected shock) form locally. Also the entropy satisfaction of this solution is presented.展开更多
The dynamics differential equations are constructed, and the initial conditions are also given. Simulation shows the following conclusions： The water pressure in cylinder has great instantaneous pulsation and phase s...The dynamics differential equations are constructed, and the initial conditions are also given. Simulation shows the following conclusions： The water pressure in cylinder has great instantaneous pulsation and phase step when outlet valve or inlet valve opens, but is more gently in other time; The volume efficiency is influenced by the output pressure slightly, and decreases as the working rotational speed increases; When the inherent frequency of the valves is integer multiple of the working frequency, the volume efficiency of system will decrease evidently.展开更多
In this paper, we study the initial-boundary value problem with rigid wall for the equations in combustion dynamics with largy parameter. Introducing variable scalar norms and two seminorms, making use of the vorticit...In this paper, we study the initial-boundary value problem with rigid wall for the equations in combustion dynamics with largy parameter. Introducing variable scalar norms and two seminorms, making use of the vorticity operator, overcome the difficulty from the large parameter. By energy estimation, the existence and unique theorems of local smooth solution is proved.展开更多
Axial Fuel Staging(AFS)technology is an advanced low-emission combustion method in modem gas turbine,which divides the combustor into two axially arranged combustion zones.For revealing the characteristics of axial st...Axial Fuel Staging(AFS)technology is an advanced low-emission combustion method in modem gas turbine,which divides the combustor into two axially arranged combustion zones.For revealing the characteristics of axial staged combustion,an industrial-grade combustor was designed and built.The distribution of temperature and velocity field in the combustor was presented with numerical simulation.And an Atmospheric Combustor Test Rig for axial staged combustion was built.The flow resistance characteristics of the combustor were measured at first.Then the effects of the equivalent ratio and the preheating temperature on the pollutant emission and combustion instability were investigated.The results show that the total pressure recovery coefficient in cold state is always above 98%;starting the secondary combustion at low load can reduce NO emissions by 50%,and can suppress the combustion oscillation amplitude of the combustor.At the design point with φ=0.62 and preheating temperature=400°C,NO emission and CO emission are 15.68 and 4.22 mg/m^(3)(@15%O_(2)).展开更多
基金the Program of Key Laboratory of Military Defenses(No.00JS75.1.1.QT1901).
文摘The transition from a deflagration to a detonation (DDT) in gas dynamics is investigated through the process of a deflagration with a imite width flame overtaken by a shock. The problem is formulated as a free boundary value problem in an angular domain with a strong detonation and a reflected shock as boundaries. The main difficulty lies in the fact that the strength of reflected shock is zero at the vertex where the shock speed degenerates to be the same as the characteristic speed. The conclusion is that a strong detonation and a retonation (a reflected shock) form locally. Also the entropy satisfaction of this solution is presented.
基金This project is supported by National Natural Science Foundation of China(No.10342003).
文摘The dynamics differential equations are constructed, and the initial conditions are also given. Simulation shows the following conclusions： The water pressure in cylinder has great instantaneous pulsation and phase step when outlet valve or inlet valve opens, but is more gently in other time; The volume efficiency is influenced by the output pressure slightly, and decreases as the working rotational speed increases; When the inherent frequency of the valves is integer multiple of the working frequency, the volume efficiency of system will decrease evidently.
文摘In this paper, we study the initial-boundary value problem with rigid wall for the equations in combustion dynamics with largy parameter. Introducing variable scalar norms and two seminorms, making use of the vorticity operator, overcome the difficulty from the large parameter. By energy estimation, the existence and unique theorems of local smooth solution is proved.
基金The authors would like to acknowledge the financial supports from National Science and Technology Major Project(2017-V-0012-0064)of China and National Natural Science Foundation of China(No.51876123).
文摘Axial Fuel Staging(AFS)technology is an advanced low-emission combustion method in modem gas turbine,which divides the combustor into two axially arranged combustion zones.For revealing the characteristics of axial staged combustion,an industrial-grade combustor was designed and built.The distribution of temperature and velocity field in the combustor was presented with numerical simulation.And an Atmospheric Combustor Test Rig for axial staged combustion was built.The flow resistance characteristics of the combustor were measured at first.Then the effects of the equivalent ratio and the preheating temperature on the pollutant emission and combustion instability were investigated.The results show that the total pressure recovery coefficient in cold state is always above 98%;starting the secondary combustion at low load can reduce NO emissions by 50%,and can suppress the combustion oscillation amplitude of the combustor.At the design point with φ=0.62 and preheating temperature=400°C,NO emission and CO emission are 15.68 and 4.22 mg/m^(3)(@15%O_(2)).
