离心压气机非轴对称流动特性及进气畸变对内部流场的影响研究
发布时间：2019-07-08 18:25
【摘要】：离心压气机作为小型燃气轮机及涡轮增压器的核心部件,被广泛应用于军事、民用领域。压气机蜗壳周向非对称的几何结构使得蜗壳内部静压周向分布不均匀,从而导致非设计工况下压气机性能下降。另一方面,离心压气机设计一般是在均匀进气的前提下进行,而实际使用中由于受整机空间布置等限制,压气机进气常采用不同形式的弯扭管道,而弯扭管道的导流作用使叶轮进口出现复杂的总压和旋涡畸变,这不但影响压气机的性能和稳定工作范围,还会引起压气机的可靠性和稳定性发生变化。本文以J90-2型离心压气机为研究对象,通过实验和数值模拟的方法研究了压气机的非轴对称流动特性及进气畸变对其内部流场的影响。主要研究目的在于:一是通过分析离心压气机蜗壳内部高静压区域产生的扰动压力波动沿叶轮槽道逆向传播的过程,揭示压气机非轴对称流动特性的形成机理,并阐明由此引起的内部流场变化以及对叶轮进出口气流参数、叶片载荷的影响机制。二是阐明弯扭管道出口截面上二次流场结构、总压和旋涡畸变特性随管道扭转角度的演化规律。定量确定不同弯扭管道出口截面上的旋涡强度、旋涡方向、旋涡对数等描述畸变流场细节的参数存在的差别。三是研究叶轮进口旋涡畸变引起的离心压气机性能变化及其原因。发现叶轮进口气流旋涡畸变指数与叶轮进气条件间的关联关系,分析进气畸变与蜗壳静压畸变的耦合特征,关注不同旋涡畸变进气时压气机内部流场的变化特点。基于上述研究目的,本文通过对不同弯扭管道进行设计,建立了带有直管以及典型的弯扭进气管道的压气机几何模型,并选用NUMECA软件展开了数值研究工作。与此同时,实验研究在不同的压气机转速和流量工况下开展,实验中分别在进口接入直管和上述典型的弯扭管道,同时测量压气机内部壁面关键点的静压变化。通过压气机直管进气下的实验验证了数值计算的可靠性,同时获得弯扭管道进气引起压气机性能和测点静压的变化规律。通过数值计算得到一系列弯扭管道进气下的总压以及旋涡畸变形式,在对气流畸变程度量化描述的基础上总结出畸变随流量变化的特点。研究发现,改变弯扭管道的扭转角度可以在管道出口得到较为典型的旋涡结构:当扭转角度为0°和180°时,旋涡结构对应孪生涡的形式;当扭转角度为90°,旋涡近似呈现团涡的特征。研究表明,与叶轮进口形成的孪生涡相比,近似团涡的旋涡形式对压气机性能的影响有显著差异,当近似团涡的旋涡方向与叶轮转动方向相同时,压气机性能下降程度最大;而旋涡方向与叶轮转动方向相反时,对压气机性能的影响最小。在非设计流量工况下,对于离心压气机的非轴对称流动特性研究方面,实验和数值模拟证实了蜗壳静压对压气机轮缘及进口静压分布产生的影响。通过叶片槽道静压变化时空图展示了蜗壳高静压扰动压力波动在叶轮流场中逆向传播的途径,发现大流量工况下蜗壳高静压扰动压力波可以传播到叶轮进口,而小流量工况下,蜗壳静压扰动压力波强度较弱,对叶轮进口几乎不产生影响。通过对比叶轮进出口气流参数的变化情况和叶轮槽道流量分配形式,表明小流量工况的影响较大。同时,进一步分析了非轴对称流动对叶片载荷分布和波动形式的影响,得到叶片载荷波动的频谱特性。大流量工况下,主叶片表面载荷波动主要受基频影响,而小流量工况下主要受2倍频的影响。在典型弯扭管道进气对压气机性能和内部流动的影响研究方面,明确了叶轮进口旋涡畸变是影响压气机性能的主要因素,全面阐述了不同叶高气流旋涡角度、旋涡强度与相对气流角之间的关联关系,研究发现:叶轮进口气流旋涡在不同叶高位置上的旋涡角度和强度改变了叶片前缘相对气流角,进而对进气攻角产生明显影响,这是造成压气机性能变化的根本原因。叶轮进口的旋涡畸变引起的正攻角增大使叶尖间隙泄漏流的发生位置向叶片前缘移动,间隙泄漏流强度也随之增大;正攻角减小或出现负攻角时,叶尖间隙泄漏流发生的位置向叶片尾缘移动。叶片槽道内流过的空气流量受进口畸变流场结构和蜗壳内部静压分布的双重因素影响,叶轮进口的孪生旋涡形式明显扩大了叶轮出口周向静压梯度,使叶轮各槽道流量分配的不平衡性显著增加;而近似团涡的旋涡形式对叶轮各槽道流量分配影响较小。另外,当叶轮进口气流对涡结构的对称度较高时,对叶片载荷波动的影响较小,而旋涡形式近似成团涡时,对叶片载荷波动影响较大。
文内图片：
图片说明：压气机轮缘测点测点静压变化
[Abstract]:As the core component of small gas turbine and turbocharger, centrifugal compressor is widely used in military and civil fields. The asymmetric geometry of the compressor volute is such that the static pressure in the spiral case is not uniform in the circumferential direction, resulting in a decrease in the performance of the compressor under the non-design condition. on the other hand, the design of the centrifugal compressor is generally carried out on the premise of uniform air intake, and in the actual use, due to the limitation of the space arrangement of the whole machine, the air inlet of the compressor often adopts a different form of the twisted pipe, The flow-guiding effect of the bent-and-torsion pipe makes the inlet of the impeller complex total pressure and vortex distortion, which not only affects the performance and the stable operating range of the compressor, but also causes the reliability and stability of the compressor to change. In this paper, a J90-2 centrifugal compressor is used as the research object, and the influence of the non-axisymmetric flow characteristics and the intake distortion on the internal flow field of the compressor is studied by means of experimental and numerical simulation. The main research aim is to reveal the formation mechanism of the non-axisymmetric flow characteristics of the compressor by analyzing the disturbance pressure fluctuation generated by the high static pressure region in the volute of the centrifugal compressor, And the influence mechanism of the flow parameters and the blade load on the inlet and outlet of the impeller. The second is to clarify the evolution of the secondary flow field structure, total pressure and vortex distortion in the outlet section of the twisted pipe. The differences in the parameters of the detail of the distortion flow field such as the vortex strength, the vortex direction, the vortex log and the like on the outlet cross-section of the different bent-and-twisted pipe are quantitatively determined. Thirdly, the performance of the centrifugal compressor caused by the vortex distortion of the impeller is studied. The relationship between the vortex distortion index of the inlet air flow and the air inlet condition of the impeller is found, and the coupling characteristics of the inlet distortion and the static pressure distortion of the spiral case are analyzed. Based on the above research, this paper establishes a compressor geometry model with a straight pipe and a typical twisted-and-twisted air inlet duct through the design of different bent-and-twisted pipes, and a numerical study is carried out using the NUMECA software. At the same time, the experimental research is carried out under different compressor speed and flow conditions, and the static pressure changes of key points in the inner wall of the compressor are measured at the same time in the experiment. The reliability of the numerical calculation is verified by the experiment under the air inlet of the compressor straight pipe, and the variation law of the compressor performance and the static pressure of the measuring point is obtained. The total pressure and the form of the vortex distortion are obtained by numerical calculation, and the characteristics of the distortion with the flow rate are summarized on the basis of the description of the degree of distortion of the air flow. It is found that changing the twist angle of the twisted pipe can get a typical vortex structure at the outlet of the pipe. When the twist angle is 0 掳 and 180 掳, the vortex structure corresponds to the form of the twin vortex. When the twist angle is 90 掳, the vortex approximation presents the characteristic of the group vortex. The results show that, compared with the twin vortex formed by the inlet of the impeller, the vortex form of the approximate group vortex has a significant difference in the performance of the compressor, and when the vortex direction of the approximate group vortex is the same as the rotation direction of the impeller, the performance of the compressor is the greatest; And the vortex direction is the same as the rotation direction of the impeller, and the effect on the performance of the compressor is minimized. In the non-designed flow condition, for the non-axisymmetric flow characteristics of the centrifugal compressor, the influence of the static pressure of the volute on the compressor wheel rim and the inlet static pressure distribution is verified by the experimental and numerical simulation. in that case of large flow condition, the pressure wave of the high static pressure disturbance of the spiral case can be transmitted to the inlet of the impeller, and under the condition of small flow, The pressure wave intensity of the static pressure disturbance of the spiral case is weak, which has little effect on the inlet of the impeller. By comparing the change of the inlet and outlet flow parameters of the impeller and the flow distribution of the impeller channel, it is indicated that the influence of the small flow condition is large. At the same time, the influence of the non-axisymmetric flow on the blade load distribution and the wave form is further analyzed, and the spectral characteristic of the blade load fluctuation is obtained. Under the condition of large flow, the main blade surface load fluctuation is mainly affected by the fundamental frequency, and under the condition of small flow, the influence of frequency doubling is mainly affected. In that study of the effect of inlet on the performance and internal flow of the compressor, it is clear that the vortex distortion of the inlet of the impeller is the main factor that affect the performance of the compressor. The results show that the vortex angle and the intensity of the vortex in the high position of the inlet of the impeller change the relative air flow angle of the leading edge of the blade, and then the angle of attack of the intake air is obviously affected, which is the root cause of the change of the performance of the compressor. The positive angle of attack caused by the vortex distortion of the impeller inlet increases the position of the tip clearance leakage flow to the leading edge of the blade, and the strength of the gap leakage flow is also increased; when the positive attack angle is reduced or the negative attack angle is present, the position of the tip clearance leakage flow is moved toward the trailing edge of the blade. The air flow in the blade channel is affected by the inlet distorted flow field structure and the static pressure distribution in the spiral case. The twin vortex form of the impeller inlet obviously increases the circumferential static pressure gradient of the impeller outlet, so that the imbalance of the flow distribution of each channel of the impeller is obviously increased; And the vortex form of the approximate group vortex has less influence on the flow distribution of each channel of the impeller. In addition, when the flow of the impeller inlet to the vortex structure is higher, the influence of the blade load fluctuation is small, and the effect of the vortex form on the blade load fluctuation is large.
【学位授予单位】：北京理工大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：TH452
，
本文编号：2511786
文内图片：
图片说明：压气机轮缘测点测点静压变化
[Abstract]:As the core component of small gas turbine and turbocharger, centrifugal compressor is widely used in military and civil fields. The asymmetric geometry of the compressor volute is such that the static pressure in the spiral case is not uniform in the circumferential direction, resulting in a decrease in the performance of the compressor under the non-design condition. on the other hand, the design of the centrifugal compressor is generally carried out on the premise of uniform air intake, and in the actual use, due to the limitation of the space arrangement of the whole machine, the air inlet of the compressor often adopts a different form of the twisted pipe, The flow-guiding effect of the bent-and-torsion pipe makes the inlet of the impeller complex total pressure and vortex distortion, which not only affects the performance and the stable operating range of the compressor, but also causes the reliability and stability of the compressor to change. In this paper, a J90-2 centrifugal compressor is used as the research object, and the influence of the non-axisymmetric flow characteristics and the intake distortion on the internal flow field of the compressor is studied by means of experimental and numerical simulation. The main research aim is to reveal the formation mechanism of the non-axisymmetric flow characteristics of the compressor by analyzing the disturbance pressure fluctuation generated by the high static pressure region in the volute of the centrifugal compressor, And the influence mechanism of the flow parameters and the blade load on the inlet and outlet of the impeller. The second is to clarify the evolution of the secondary flow field structure, total pressure and vortex distortion in the outlet section of the twisted pipe. The differences in the parameters of the detail of the distortion flow field such as the vortex strength, the vortex direction, the vortex log and the like on the outlet cross-section of the different bent-and-twisted pipe are quantitatively determined. Thirdly, the performance of the centrifugal compressor caused by the vortex distortion of the impeller is studied. The relationship between the vortex distortion index of the inlet air flow and the air inlet condition of the impeller is found, and the coupling characteristics of the inlet distortion and the static pressure distortion of the spiral case are analyzed. Based on the above research, this paper establishes a compressor geometry model with a straight pipe and a typical twisted-and-twisted air inlet duct through the design of different bent-and-twisted pipes, and a numerical study is carried out using the NUMECA software. At the same time, the experimental research is carried out under different compressor speed and flow conditions, and the static pressure changes of key points in the inner wall of the compressor are measured at the same time in the experiment. The reliability of the numerical calculation is verified by the experiment under the air inlet of the compressor straight pipe, and the variation law of the compressor performance and the static pressure of the measuring point is obtained. The total pressure and the form of the vortex distortion are obtained by numerical calculation, and the characteristics of the distortion with the flow rate are summarized on the basis of the description of the degree of distortion of the air flow. It is found that changing the twist angle of the twisted pipe can get a typical vortex structure at the outlet of the pipe. When the twist angle is 0 掳 and 180 掳, the vortex structure corresponds to the form of the twin vortex. When the twist angle is 90 掳, the vortex approximation presents the characteristic of the group vortex. The results show that, compared with the twin vortex formed by the inlet of the impeller, the vortex form of the approximate group vortex has a significant difference in the performance of the compressor, and when the vortex direction of the approximate group vortex is the same as the rotation direction of the impeller, the performance of the compressor is the greatest; And the vortex direction is the same as the rotation direction of the impeller, and the effect on the performance of the compressor is minimized. In the non-designed flow condition, for the non-axisymmetric flow characteristics of the centrifugal compressor, the influence of the static pressure of the volute on the compressor wheel rim and the inlet static pressure distribution is verified by the experimental and numerical simulation. in that case of large flow condition, the pressure wave of the high static pressure disturbance of the spiral case can be transmitted to the inlet of the impeller, and under the condition of small flow, The pressure wave intensity of the static pressure disturbance of the spiral case is weak, which has little effect on the inlet of the impeller. By comparing the change of the inlet and outlet flow parameters of the impeller and the flow distribution of the impeller channel, it is indicated that the influence of the small flow condition is large. At the same time, the influence of the non-axisymmetric flow on the blade load distribution and the wave form is further analyzed, and the spectral characteristic of the blade load fluctuation is obtained. Under the condition of large flow, the main blade surface load fluctuation is mainly affected by the fundamental frequency, and under the condition of small flow, the influence of frequency doubling is mainly affected. In that study of the effect of inlet on the performance and internal flow of the compressor, it is clear that the vortex distortion of the inlet of the impeller is the main factor that affect the performance of the compressor. The results show that the vortex angle and the intensity of the vortex in the high position of the inlet of the impeller change the relative air flow angle of the leading edge of the blade, and then the angle of attack of the intake air is obviously affected, which is the root cause of the change of the performance of the compressor. The positive angle of attack caused by the vortex distortion of the impeller inlet increases the position of the tip clearance leakage flow to the leading edge of the blade, and the strength of the gap leakage flow is also increased; when the positive attack angle is reduced or the negative attack angle is present, the position of the tip clearance leakage flow is moved toward the trailing edge of the blade. The air flow in the blade channel is affected by the inlet distorted flow field structure and the static pressure distribution in the spiral case. The twin vortex form of the impeller inlet obviously increases the circumferential static pressure gradient of the impeller outlet, so that the imbalance of the flow distribution of each channel of the impeller is obviously increased; And the vortex form of the approximate group vortex has less influence on the flow distribution of each channel of the impeller. In addition, when the flow of the impeller inlet to the vortex structure is higher, the influence of the blade load fluctuation is small, and the effect of the vortex form on the blade load fluctuation is large.
【学位授予单位】：北京理工大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：TH452
，
本文编号：2511786
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