安裝角及雷諾數(shù)對壓氣機葉柵氣動噪聲特性的影響
發(fā)布時間：2019-01-26 12:30
【摘要】：葉型/葉柵的氣動參數(shù)對壓氣機氣動性能有著很大的影響，研究人員通過實驗和數(shù)值模擬方法致力于葉型/葉柵氣動性能的研究，并取得了詳實的研究成果。隨著社會和經(jīng)濟的發(fā)展，人們對周圍環(huán)境舒適性的要求越來越高，葉輪機械的氣動噪聲逐漸成為人們關(guān)注熱點。因此，葉型/葉柵的流動誘導(dǎo)噪聲與氣動性能的關(guān)系也成為設(shè)計者必須了解的問題。 氣流流經(jīng)葉柵表面時，形成紊流附面層并發(fā)生尾渦脫落，產(chǎn)生的壓力脈動作用在葉柵表面，形成偶極子噪聲源；當(dāng)附面層發(fā)展到一定程度，或者來流攻角比較大時，葉柵表面將發(fā)生明顯的流動分離，引起葉柵表面壓力脈動特征改變，從而影響葉柵流場輻射噪聲。本文在葉柵稠度為1.0的條件下改變安裝角獲得了三種不同的NACA651210平面葉柵，然后結(jié)合計算流體力學(xué)和邊界元方法數(shù)值模擬葉柵通道內(nèi)的湍流場及流場輻射的噪聲，研究安裝角、自由來流雷諾數(shù)和來流攻角對葉柵通道內(nèi)非定常流動特征以及葉柵流場輻射噪聲的影響。主要工作和結(jié)果如下： (1)本文重點研究網(wǎng)格尺度、聲源信息采樣點長度對流場以及聲場計算的影響，并結(jié)合前人的實驗數(shù)據(jù)對整個計算方法的精度及準(zhǔn)確度進行了驗證。 (2)在來流雷諾數(shù)為252000、安裝角為30°、來流攻角為-5°~20°時，計算葉柵通道內(nèi)的湍流場以及流場誘導(dǎo)噪聲，分析渦量、瞬時流線、葉型尾緣點的壓力脈動以及遠場聲壓輻射隨攻角的變化規(guī)律。計算結(jié)果如下：葉型尾緣點的渦脫落頻率隨著來流攻角的增大而降低，，大的正攻角下，低頻脈動占主導(dǎo)成分。攻角為5°時，渦脫落頻率呈現(xiàn)出明顯的離散特征；而負攻角以及大的正攻角下，呈現(xiàn)出寬頻特征。監(jiān)測點壓力脈動幅值隨攻角的增大而減小。對于葉柵外場監(jiān)測點的總聲壓級，在0°攻角下出現(xiàn)最小值，為6.5dB；攻角為-5°和5°時，總聲壓級急劇增大；隨著攻角增大到5°~20°時，總聲壓增大趨勢變緩�？偮晧杭壟c阻力系數(shù)隨攻角的變化趨勢并不一致。 (3)在來流雷諾數(shù)為252000，安裝角分別為45°、60°時，由流場和聲場計算信息可知，葉型尾緣點的渦脫落頻率隨攻角的變化趨勢同安裝角為30°時基本一致，除負攻角外，渦脫落頻率隨著攻角的增大而降低。不同安裝角下，葉柵外場監(jiān)測點總聲壓級均是在0°達到最小值，且安裝角為60°時的總聲壓級較其它安裝角增加了近6dB；負攻角下，隨著安裝角的增大，總聲壓級逐漸增大；攻角為5°~20°時，安裝角為60°的總聲壓級相對于其它安裝角反而降低。結(jié)合流場信息，我們可以推測，安裝角為60°時，大的正攻角下，葉柵吸力面的耗散現(xiàn)象變得嚴(yán)重，消耗一部分能量，從而使聲壓級降低。 (4)在安裝角為30°，來流攻角為0°時，隨著雷諾數(shù)的增大，葉型尾緣點的壓力脈動幅值增強；外場輻射聲壓變大；邊界層變薄，流動損失降低。
[Abstract]:The aerodynamic parameters of the blade / cascade have a great influence on the aerodynamic performance of the compressor. The researchers have devoted themselves to the study of the aerodynamic performance of the blade / cascade by means of experiments and numerical simulation, and obtained detailed research results. With the development of society and economy, people need more and more comfortable environment. The aerodynamic noise of impeller machinery has become a hot spot. Therefore, the relationship between flow-induced noise and aerodynamic performance of blade / cascade is also a problem that designers must understand. When the air flow through the cascade surface, the turbulent boundary layer is formed and the wake vortex shedding, resulting in pressure pulsation acting on the cascade surface to form a dipole noise source. When the boundary layer develops to a certain extent or the angle of attack is large, the flow separation on the cascade surface will take place, which will change the pressure pulsation characteristics of the cascade surface and affect the radiation noise of the cascade flow field. In this paper, three different NACA651210 planar cascades are obtained by changing the installation angle when the cascade consistency is 1.0. The turbulent field and the noise emitted from the flow field in the cascade channel are numerically simulated by using computational fluid dynamics and boundary element method. The effects of installation angle, free flow Reynolds number and angle of attack on the unsteady flow in the cascade channel and the radiated noise in the cascade flow field are studied. The main work and results are as follows: (1) this paper focuses on the effects of mesh scale, the length of sound source information sampling point and the calculation of sound field. The accuracy and accuracy of the whole method are verified with the experimental data. (2) when the flow Reynolds number is 252000, the installation angle is 30 擄and the attack angle is -5 擄~ 20 擄, the turbulent field and the induced noise in the cascade channel are calculated, and the vorticity and instantaneous streamlines are analyzed. The pressure pulsation at the tip of the blade and the variation of far field sound pressure radiation with the angle of attack. The results are as follows: the frequency of vortex shedding decreases with the increase of the angle of attack, and the low frequency pulsation is the dominant component at the large positive angle of attack. When the angle of attack is 5 擄, the frequency of vortex shedding is discrete, while the negative angle of attack and the large positive angle of attack show wide band characteristics. The amplitude of pressure fluctuation decreases with the increase of attack angle. For the total sound pressure level of the field monitoring point in the cascade, the minimum is 6.5 dB at 0 擄attack angle, the total sound pressure level increases sharply when the attack angle is -5 擄and 5 擄, and the total sound pressure increases slowly with the increase of attack angle to 5 擄~ 20 擄. The variation of total sound pressure level and resistance coefficient with angle of attack is not consistent. (3) when the flow Reynolds number is 252000, the installation angles are 45 擄and 60 擄, the calculated information of the flow field and sound field show that the vortex shedding frequency of the tip edge of the blade shape is basically the same as the angle of attack when the angle of attack is 30 擄, except for the negative angle of attack. The frequency of vortex shedding decreases with the increase of angle of attack. At different installation angles, the total sound pressure level of the monitoring points in the field of the cascade reaches the minimum at 0 擄, and the total sound pressure level at the installation angle of 60 擄increases by nearly 6 dB compared with the other installation angles, and the total sound pressure level increases gradually with the increase of the installation angle under the negative angle of attack. When the angle of attack is 5 擄~ 20 擄, the total sound pressure level of 60 擄is lower than that of other angles. Combined with the flow field information, we can infer that when the installation angle is 60 擄, the dissipation of the suction surface of the cascade becomes serious at the large positive angle of attack, and part of the energy is consumed, thus reducing the sound pressure level. (4) when the angle of installation is 30 擄and the angle of attack is 0 擄, with the increase of Reynolds number, the amplitude of pressure pulsation at the tip of the blade increases, the sound pressure of the external field radiation becomes larger, the boundary layer becomes thinner and the flow loss decreases.
【學(xué)位授予單位】：上海理工大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2012
【分類號】：TH45
本文編號：2415483
[Abstract]:The aerodynamic parameters of the blade / cascade have a great influence on the aerodynamic performance of the compressor. The researchers have devoted themselves to the study of the aerodynamic performance of the blade / cascade by means of experiments and numerical simulation, and obtained detailed research results. With the development of society and economy, people need more and more comfortable environment. The aerodynamic noise of impeller machinery has become a hot spot. Therefore, the relationship between flow-induced noise and aerodynamic performance of blade / cascade is also a problem that designers must understand. When the air flow through the cascade surface, the turbulent boundary layer is formed and the wake vortex shedding, resulting in pressure pulsation acting on the cascade surface to form a dipole noise source. When the boundary layer develops to a certain extent or the angle of attack is large, the flow separation on the cascade surface will take place, which will change the pressure pulsation characteristics of the cascade surface and affect the radiation noise of the cascade flow field. In this paper, three different NACA651210 planar cascades are obtained by changing the installation angle when the cascade consistency is 1.0. The turbulent field and the noise emitted from the flow field in the cascade channel are numerically simulated by using computational fluid dynamics and boundary element method. The effects of installation angle, free flow Reynolds number and angle of attack on the unsteady flow in the cascade channel and the radiated noise in the cascade flow field are studied. The main work and results are as follows: (1) this paper focuses on the effects of mesh scale, the length of sound source information sampling point and the calculation of sound field. The accuracy and accuracy of the whole method are verified with the experimental data. (2) when the flow Reynolds number is 252000, the installation angle is 30 擄and the attack angle is -5 擄~ 20 擄, the turbulent field and the induced noise in the cascade channel are calculated, and the vorticity and instantaneous streamlines are analyzed. The pressure pulsation at the tip of the blade and the variation of far field sound pressure radiation with the angle of attack. The results are as follows: the frequency of vortex shedding decreases with the increase of the angle of attack, and the low frequency pulsation is the dominant component at the large positive angle of attack. When the angle of attack is 5 擄, the frequency of vortex shedding is discrete, while the negative angle of attack and the large positive angle of attack show wide band characteristics. The amplitude of pressure fluctuation decreases with the increase of attack angle. For the total sound pressure level of the field monitoring point in the cascade, the minimum is 6.5 dB at 0 擄attack angle, the total sound pressure level increases sharply when the attack angle is -5 擄and 5 擄, and the total sound pressure increases slowly with the increase of attack angle to 5 擄~ 20 擄. The variation of total sound pressure level and resistance coefficient with angle of attack is not consistent. (3) when the flow Reynolds number is 252000, the installation angles are 45 擄and 60 擄, the calculated information of the flow field and sound field show that the vortex shedding frequency of the tip edge of the blade shape is basically the same as the angle of attack when the angle of attack is 30 擄, except for the negative angle of attack. The frequency of vortex shedding decreases with the increase of angle of attack. At different installation angles, the total sound pressure level of the monitoring points in the field of the cascade reaches the minimum at 0 擄, and the total sound pressure level at the installation angle of 60 擄increases by nearly 6 dB compared with the other installation angles, and the total sound pressure level increases gradually with the increase of the installation angle under the negative angle of attack. When the angle of attack is 5 擄~ 20 擄, the total sound pressure level of 60 擄is lower than that of other angles. Combined with the flow field information, we can infer that when the installation angle is 60 擄, the dissipation of the suction surface of the cascade becomes serious at the large positive angle of attack, and part of the energy is consumed, thus reducing the sound pressure level. (4) when the angle of installation is 30 擄and the angle of attack is 0 擄, with the increase of Reynolds number, the amplitude of pressure pulsation at the tip of the blade increases, the sound pressure of the external field radiation becomes larger, the boundary layer becomes thinner and the flow loss decreases.
【學(xué)位授予單位】：上海理工大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2012
【分類號】：TH45
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