氢燃料旋流预混火焰燃烧诱导涡破碎回火特性研究
发布时间：2018-09-04 19:29
【摘要】：为了实现近零污染排放,在整体煤气化联合循环系统中集成燃烧前碳捕集技术被认为是可行性最高的方法之一。此时氢气或富氢气体将作为燃料送入燃气轮机中,因此首先需要发展氢燃机技术。然而回火,尤其是燃烧诱导涡破碎(Combustion Induced Vortex Breakdown, CT WB)回火阻碍了氢燃机的发展。本文将数值模拟与实验结合起来,针对氢燃料旋流预混火焰的CIVB回火特性进行了分析和探讨。首先收集了氢燃料燃烧特性数据并筛选出合适的化学反应机理和数值模拟计算模型,为进一步开展CIVB回火模拟工作打下了基础。随后,采用正交试验设计方法进行数值试验方案的安排,通过对数值模拟结果的分析,确定了影响CIVB回火的各参数的主次排序及影响趋势,并结合方差分析方法指出了具有显著影响的参数。然后开展了相关的实验研究工作,验证了数值模拟结果的可靠性。此外,在数值模拟过程中通过分析位于预混段内靠近中心体壁面(对于有中心体的结构)或者预混段中心线(对于无中心体的结构)附近上下游两点的轴向速度、压力、温度和切向涡量等物理量随着当量比的变化趋势,澄清了CIVB回火发生的过程,并提出了CIVB回火的机理。最后应用上述研究结果提出了两种抑制CIVB回火的方法。本文的主要结论如下：1.多参数对CIVB回火影响的数值研究综合分析结构参数和运行参数对CNB回火临界当量比的影响,按照其影响程度的主次排序为：旋流器结构预混段结构空气入口温度燃料组分火焰筒结构质量流量。其中,前四个因素对CNB回火具有高度显著的影响,是在设计过程中需要重点考虑的因素。数值模拟结果证明各个参数是通过改变流场分布和火焰特性而作用于CIVB回火。根据多参数分析的结果将现有仅适用于特定几何结构的时间尺度模型扩展至变几何结构。这样,通过一次试验确定初始结构的熄火常数Cq后,便可计算出运行条件和几何结构变化时的回火临界当量比,而无需进行额外的试验,对燃烧室的改进设计具有定量的指导意义。2.多参数对CIVB回火影响的实验研究实验结果证实了通过数值模拟得到的预混段结构、质量流量和燃料组分对CIVB回火影响程度排序的可靠性。此外还证实了扩展的时间尺度模型的确可适用于不同的预混段结构,并发现熄火常数Cq正比于空气质量流量。3.CIVB回火发生过程和机理的研究CIVB回火过程可被分为三个阶段：火焰向上游传播、涡破碎和火焰稳定。这三个阶段可分别采用一维守恒模型、涡量输运方程模型和时间尺度模型进行描述。这三个阶段的划分、一维守恒模型和时间尺度模型都具有普遍适用性,与所采用的燃料组分和几何结构无关。然而,涡破碎发生过程以及对应的涡量输运方程模型则与几何结构(中心体)密切相关。当有中心体存在时,涡破碎的过程为：由于旋流及粘性作用预混段内靠近中心体区域下游与上游位置间的压差增大,使得局部轴向速度降低、静压增大,从而促进迹线的发散,切向涡量开始起作用。切向涡量诱导出的速度始终与轴向速度相反,而轴向速度的大小又会影响切向涡量值,两者之间的相互作用会建立一个新的平衡状态。此时,轴向速度达到最小值、静压和压差达到最大值,随后发生涡破碎。当无中心体存在时,涡破碎的发生过程与有中心体的结构基本一致,只是切向涡量和轴向速度之间是相互促进的,只有当两者同时达到最小值时才会发生涡破碎。在此过程中没有建立新的平衡态。涡破碎发生的过程构成CIVB回火发生的流场路线。火焰向上游传播并稳定在破碎的涡内构成CIVB回火发生的火焰路线。发生涡破碎的不可逆能量损失使得回火驱动力压差显著降低,无力再维持流场路线和火焰路线的改变,构成CIVB回火发生的反馈路线。三条路线紧密地连接在一起,共同促进CIVB回火的发生。4.CIVB回火控制方法的提出根据CIVB回火多参数分析的结论,可以通过调整预混段结构和旋流器结构实现CIVB回火的被动控制。也就是说,对一个初始设计方案通过试验确定其熄火常数Cq后便可根据Cq和预期的回火临界当量比计算出所需要的几何结构参数。此外,基于CIVB回火发生的机理,提出了一种对CIVB回火进行主动控制的方法,即在预混段最前端且靠近中心体壁面区域引入一股额外的气流来降低中心体壁面附近下游与上游间的压差,从而抑制CIVB回火。通过比较这两种方法实施的难度和可靠性,本文推荐现阶段最好采用被动控制方法,而主动控制方法可以作为下一阶段的研究目标。5.对氢燃料旋流贫预混燃烧室初步设计的建议与传统的天然气燃料旋流贫预混燃烧室相比,在进行氢燃料燃烧室初步设计时应：(1)同时验证冷态速度场和温度场；(2)特别注意旋流器结构和预混段结构参数的选取,尽量采用较低的旋流数；(3)避免在燃料喷射区域或旋流器叶片尾缘区域形成尾迹涡。综上所述,本文通过数值模拟结合正交试验设计方法掌握了燃烧室几何结构参数和运行参数对CIVB回火影响的规律,阐明了CIVB回火发生的过程和机理,并据此提出了CIVB回火的控制方法,给出了氢燃料旋流贫预混燃烧室在初步设计时的建议。
[Abstract]:In order to achieve near-zero pollution emissions, integrated pre-combustion carbon capture technology is considered one of the most feasible methods in the integrated coal gasification combined cycle system. At this time, hydrogen or hydrogen-rich gases will be fed into the gas turbine as fuel, so hydrogen turbine technology needs to be developed first. However, tempering, especially Combustion-Induced Vortex Breakage (CIVBR) is one of the most feasible methods. On-Induced Vortex Breakdown (CT WB) tempering hinders the development of hydrogen-fired engines. Combining numerical simulation with experiment, the tempering characteristics of hydrogen-fired swirl premixed flame are analyzed and discussed. Firstly, the combustion characteristics of hydrogen fuel are collected and the appropriate chemical reaction mechanism and numerical simulation model are selected. Then, the orthogonal experimental design method is used to arrange the numerical test scheme. Through the analysis of the numerical simulation results, the primary and secondary order of the parameters affecting the CIVB tempering and the influence trend are determined, and the parameters which have significant influence are pointed out with the method of variance analysis. In addition, the axial velocities, pressures, temperatures and temperatures of the upstream and downstream points located in the premixed section near the center wall (for the structure with a center) or the center line of the premixed section (for the structure without a center) are analyzed during the numerical simulation. The tangential vorticity and other physical quantities change with the equivalent ratio, clarifying the process of CIVB tempering, and putting forward the mechanism of CIVB tempering. Finally, two methods of restraining CIVB tempering are put forward based on the above research results. The main conclusions of this paper are as follows: 1. Numerical study on the influence of multi-parameters on CIVB tempering comprehensively analyzes the structural parameters and transportation. The influence of row parameters on the critical equivalence ratio of CNB tempering is in the order of the air inlet temperature of the premixed section of the swirler structure and the mass flow rate of the fuel composition flame tube structure. The results show that each parameter acts on CIVB tempering by changing the flow field distribution and flame characteristics. According to the results of the multi-parameter analysis, the existing time-scale models which are only suitable for specific geometric structures are extended to variable geometric structures. The critical equivalence ratio of tempering when the geometry of the combustor changes without additional tests is of quantitative significance for improving the design of the combustor. In addition, the reliability of the extended time-scale model is verified. It is found that the quenching constant Cq is proportional to the air mass flow rate. 3. The CIVB tempering process can be divided into three stages: flame propagation upstream, vortex breaking and flame stability. One-dimensional conservation model, vorticity transport equation model and time-scale model can be used to describe the three stages respectively. The three stages, one-dimensional conservation model and time-scale model, have universal applicability and are independent of the fuel composition and geometric structure used. However, the process of vortex breakup and the corresponding vorticity transport equation model When there is a central body, the process of vortex breakup is that the local axial velocity decreases and the static pressure increases due to the pressure difference between the downstream and the upstream positions near the central body region in the premixed section due to the swirl and viscous action, which promotes the divergence of the trace and the tangential vorticity begins to take effect. The velocity induced by vorticity is always opposite to the axial velocity, and the magnitude of the axial velocity will affect the tangential vorticity. The interaction between the two will create a new equilibrium state. The vortex breakage occurs only when the tangential vorticity and axial velocity reach the minimum value simultaneously. No new equilibrium state is established in the process. The process of vortex breakage forms the flow field route of CIVB tempering. The irreversible energy loss caused by the vortex breakage makes the driving force pressure drop remarkably reduced, and the flow field and flame path can not be maintained to form the feedback route of CIVB tempering. According to the conclusion of multi-parameter analysis of CIVB tempering, the passive control of CIVB tempering can be realized by adjusting the structure of premixed section and cyclone. That is to say, after determining the extinguishing constant Cq of an initial design scheme through experiment, the required Cq and the expected critical equivalent ratio of tempering can be calculated. In addition, based on the mechanism of CIVB tempering, a method of active control of CIVB tempering is proposed, that is, introducing an additional air stream into the front of the premixed section and near the center wall to reduce the pressure difference between the upstream and downstream near the center wall to suppress the CIVB tempering. It is recommended that the passive control method should be adopted at the present stage, and the active control method can be used as the research objective in the next stage. 5. Proposals for preliminary design of hydrogen fuel swirl lean premixed combustor are compared with the traditional natural gas fuel swirl lean premixed combustor. The design should: (1) verify the cold velocity and temperature fields at the same time; (2) pay special attention to the selection of the structure parameters of the cyclone and the premixed section, and try to use a lower number of swirls; (3) avoid the formation of wake vortices in the fuel injection region or the trailing edge region of the cyclone blade. The influence of combustion chamber geometry parameters and operation parameters on CIVB tempering is mastered. The process and mechanism of CIVB tempering are expounded. The control method of CIVB tempering is put forward. Suggestions for preliminary design of hydrogen swirl lean premixed combustion chamber are given.
【学位授予单位】：中国科学院研究生院(工程热物理研究所)
【学位级别】：博士
【学位授予年份】：2015
【分类号】：TK16
本文编号：2223124
[Abstract]:In order to achieve near-zero pollution emissions, integrated pre-combustion carbon capture technology is considered one of the most feasible methods in the integrated coal gasification combined cycle system. At this time, hydrogen or hydrogen-rich gases will be fed into the gas turbine as fuel, so hydrogen turbine technology needs to be developed first. However, tempering, especially Combustion-Induced Vortex Breakage (CIVBR) is one of the most feasible methods. On-Induced Vortex Breakdown (CT WB) tempering hinders the development of hydrogen-fired engines. Combining numerical simulation with experiment, the tempering characteristics of hydrogen-fired swirl premixed flame are analyzed and discussed. Firstly, the combustion characteristics of hydrogen fuel are collected and the appropriate chemical reaction mechanism and numerical simulation model are selected. Then, the orthogonal experimental design method is used to arrange the numerical test scheme. Through the analysis of the numerical simulation results, the primary and secondary order of the parameters affecting the CIVB tempering and the influence trend are determined, and the parameters which have significant influence are pointed out with the method of variance analysis. In addition, the axial velocities, pressures, temperatures and temperatures of the upstream and downstream points located in the premixed section near the center wall (for the structure with a center) or the center line of the premixed section (for the structure without a center) are analyzed during the numerical simulation. The tangential vorticity and other physical quantities change with the equivalent ratio, clarifying the process of CIVB tempering, and putting forward the mechanism of CIVB tempering. Finally, two methods of restraining CIVB tempering are put forward based on the above research results. The main conclusions of this paper are as follows: 1. Numerical study on the influence of multi-parameters on CIVB tempering comprehensively analyzes the structural parameters and transportation. The influence of row parameters on the critical equivalence ratio of CNB tempering is in the order of the air inlet temperature of the premixed section of the swirler structure and the mass flow rate of the fuel composition flame tube structure. The results show that each parameter acts on CIVB tempering by changing the flow field distribution and flame characteristics. According to the results of the multi-parameter analysis, the existing time-scale models which are only suitable for specific geometric structures are extended to variable geometric structures. The critical equivalence ratio of tempering when the geometry of the combustor changes without additional tests is of quantitative significance for improving the design of the combustor. In addition, the reliability of the extended time-scale model is verified. It is found that the quenching constant Cq is proportional to the air mass flow rate. 3. The CIVB tempering process can be divided into three stages: flame propagation upstream, vortex breaking and flame stability. One-dimensional conservation model, vorticity transport equation model and time-scale model can be used to describe the three stages respectively. The three stages, one-dimensional conservation model and time-scale model, have universal applicability and are independent of the fuel composition and geometric structure used. However, the process of vortex breakup and the corresponding vorticity transport equation model When there is a central body, the process of vortex breakup is that the local axial velocity decreases and the static pressure increases due to the pressure difference between the downstream and the upstream positions near the central body region in the premixed section due to the swirl and viscous action, which promotes the divergence of the trace and the tangential vorticity begins to take effect. The velocity induced by vorticity is always opposite to the axial velocity, and the magnitude of the axial velocity will affect the tangential vorticity. The interaction between the two will create a new equilibrium state. The vortex breakage occurs only when the tangential vorticity and axial velocity reach the minimum value simultaneously. No new equilibrium state is established in the process. The process of vortex breakage forms the flow field route of CIVB tempering. The irreversible energy loss caused by the vortex breakage makes the driving force pressure drop remarkably reduced, and the flow field and flame path can not be maintained to form the feedback route of CIVB tempering. According to the conclusion of multi-parameter analysis of CIVB tempering, the passive control of CIVB tempering can be realized by adjusting the structure of premixed section and cyclone. That is to say, after determining the extinguishing constant Cq of an initial design scheme through experiment, the required Cq and the expected critical equivalent ratio of tempering can be calculated. In addition, based on the mechanism of CIVB tempering, a method of active control of CIVB tempering is proposed, that is, introducing an additional air stream into the front of the premixed section and near the center wall to reduce the pressure difference between the upstream and downstream near the center wall to suppress the CIVB tempering. It is recommended that the passive control method should be adopted at the present stage, and the active control method can be used as the research objective in the next stage. 5. Proposals for preliminary design of hydrogen fuel swirl lean premixed combustor are compared with the traditional natural gas fuel swirl lean premixed combustor. The design should: (1) verify the cold velocity and temperature fields at the same time; (2) pay special attention to the selection of the structure parameters of the cyclone and the premixed section, and try to use a lower number of swirls; (3) avoid the formation of wake vortices in the fuel injection region or the trailing edge region of the cyclone blade. The influence of combustion chamber geometry parameters and operation parameters on CIVB tempering is mastered. The process and mechanism of CIVB tempering are expounded. The control method of CIVB tempering is put forward. Suggestions for preliminary design of hydrogen swirl lean premixed combustion chamber are given.
【学位授予单位】：中国科学院研究生院(工程热物理研究所)
【学位级别】：博士
【学位授予年份】：2015
【分类号】：TK16
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