连续式跨声速风洞第二喉道设计技术研究
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摘要
鉴于连续式跨声速风洞在我国的需求越来越紧迫,关于大型连续式跨声速风洞的研究论证也已提上日程。为保证大型连续式风洞更好地满足风洞试验模拟精细化的要求,使其跨入国际先进跨声速风洞的行列,其流场设计指标提出了较高的要求。而第二喉道作为对风洞性能有重要影响的部段使其设计技术成为了跨声速风洞研究的关键技术之一。
第二喉道在现有风洞设备中已经得到了广泛的应用。它在跨声速状态下具有隔离上下游流场从而降低试验段噪声,精确控制马赫数的作用。气流通过时,第二喉道利用喉道截面的变化改变气流速度,使得在喉道最小截面处形成马赫数略大于1的激波。该过程所实现的堵塞,成为实现喉道在跨声速风洞精确控制马赫数的关键。超声速状态下,第二喉道对风洞效率的提高有着较为可观的作用。喉道通过降低超声速风洞形成激波的波前马赫数来减少激波损失,从而达到提高风洞效率的目的。
本文对跨声速风洞二喉道展开了研究工作,希望通过数值模拟的方法确定出满足设计需要的喉道形式。根据第二喉道的喉道截面是否可变可以将二喉道分为固定式和可调式两种形式。由于可调式二喉道在马赫数控制方面具有不可比拟的优势,设计风洞拟采用这种形式的二喉道。可调式二喉道又可分为堵块式、调节片加中心体式以及栅指式,不同形式的调节方式决定了它不同的适用性。由于堵块式调节方式结构笨重、调节困难,因此,本文主要对调节片加中心体式和栅指式这两种调节方式进行了研究。
在利用部分算例对采用的数值方法进行验证后,本文分别对调节片式和栅指式二喉道进行了数值计算。首先,为了解调节片式二喉道的收缩段、平直段、扩张段三部段对喉道性能影响的程度大小,本文针对二维情况设计了不同尺寸的模型并对数值模拟的结果进行了讨论。在所给的设计状态中,发现对喉道性能影响最大的是喉道收缩段尺寸。该部段为整个喉道气流速度变化最剧烈的区域。如果长度较短,不利于气流的平缓变化,将会对喉道性能的损失造成较大影响。喉道平直段尺寸和扩张段尺寸在所设计的模型中在损失和效率上影响较小,但是可以得出这两段尺寸适当减小后对喉道效率有利的结论。喉道平直段扩开角和中心体在平直段内的位置也是影响喉道性能两个因素。本文通过平直段取0.5°扩开角的算例验证了适当的扩开角将有助于提高喉道的效率,同时中心体位于不同位置时的算例显示,中心体位置适当后移对喉道性能的提高是有一定作用的。在积累了一定的二维经验后,本文提出了五种以600mm×600mm试验段截面为入口的三维模型,在对数值结果进行处理后,得出了效率较高的尺寸长度。
影响栅指式喉道性能影响因素较多,从翼型的选取到栅指的结构布置已经有详细的经验公式进行参考。本文选取了NACA0025翼型栅指剖面,主要研究了该翼型在不同截尾厚度时对喉道性能影响。为验证喉道翼型的区别,本文选取了一种菱形翼型,比较了钝头翼型和尖头翼型的区别。
根据数值模拟结果,可以发现调节片式喉道的效率普遍高于栅指式,因此本文建议在喉道形式的选取上应当以调节片式为主。
Owing to the need of the continuous transonic/supersonic wind tunnel which is more and more urgent in our Country, the research of 4.8m continuous transonic/supersonic wind tunnel has already begun. In order to ensure that the 4.8m wind tunnel meets the refine request of the wind tunnel experiments and becomes an advanced transonic wind tunnel in the world, its design index of the flow field gives a higher request. As an important section of the wind tunnel, the design of the second throat is one of key techniques of the research about the transonic wind tunnel.
The second throat has already got the extensive application in existing wind tunnel equipments. It can insulate the upstream and downstream flow field resulting in the noise drop of the text section from the downstream and can control the Mach number exactly in the transonic state. When the air passes, the second throat makes use of variational section area to change the speed of the air and coming into being a shock wave of which the Mach number is just greater than 1 in the minimum piece of the second throat. This process induces the choking which becomes the key to control the Mach num exactly in a transonic/supersonic wind tunnel. In the supersonic state, the second throat can improve the efficiency of the wind tunnel notablely. Via reducing the Mach number of the shock wave, the loss of the wind tunnel is reduced and the efficiency of the wind tunnel is improved.
In order to design the second throat which meets the requirement in the method of the numerical simulation, some researches on the second throat of the transonic wind tunnel are carried out in this paper. The second throat can be divided into fixed type and adjustable type. Because of the more advantage of the adjustable type, the designing wind tunnel will use this type. The adjustable type can be divided into type of center chock, type of flap, type of choke finger. The different adjustable ways of the throat have decided the different applicability. The type of center choke has an unwieldy configuration and can’t be regulated easily, so, this paper makes the important point on the type of flap and choke finger.
After validating the numerical method with some standard cases, both the second throat with flap and with choke finger is studied by numerical simulation. Firstly, a group of 2D models are established to study how contraction, straight segment, diffuser influence the performance of second throat. The results indicate that the size of contraction has significant impact on second throat performance. The speed of the air changes the most violently in this section. If the length is shorter, the speed of the air will vary very fast and this section will increase the loss of the throat. The size of the straight segment and the diffuser has less influencing on the loss and the efficiency of the throat, but, it is still can be found out that the seemly shorter length will decrease the loss. The angle of the straight segment and the placement of the center flap in the straight segment are the factors which influence the capability of the throat. Some examples about the 0.5°angle of the straight segment are given in this paper and proves that the angle can improve the efficiency of the throat. Through the examples of the different placement of the center flap in the straight segment, if putting the center flap backward seemly in the straight segment, it has some advantages to improve the efficiency of the throat. Via 2d examples, five models which have the 600mm×600mm test section are designed in this paper which gives the numerical results.
There are many factors which influence the efficiency of throat with choke finger. The aerofoil and configuration of choke finger can be calculated by experiential formulas. In this paper, the NACA0025 aerofoil is chosen for the research. The NACA0025 aerofoil becomes the section of the finger. This paper compares the different bobtail thickness which is an influencing factor to the efficiency of the throat. A rhombus aerofoil is selected in order to get the different influences of aero foils on the throat.
According to the results of the numerical simulation, the flap type is more seemly than the choke finger, so, this type of the throat is advised in this paper.
第二喉道在现有风洞设备中已经得到了广泛的应用。它在跨声速状态下具有隔离上下游流场从而降低试验段噪声,精确控制马赫数的作用。气流通过时,第二喉道利用喉道截面的变化改变气流速度,使得在喉道最小截面处形成马赫数略大于1的激波。该过程所实现的堵塞,成为实现喉道在跨声速风洞精确控制马赫数的关键。超声速状态下,第二喉道对风洞效率的提高有着较为可观的作用。喉道通过降低超声速风洞形成激波的波前马赫数来减少激波损失,从而达到提高风洞效率的目的。
本文对跨声速风洞二喉道展开了研究工作,希望通过数值模拟的方法确定出满足设计需要的喉道形式。根据第二喉道的喉道截面是否可变可以将二喉道分为固定式和可调式两种形式。由于可调式二喉道在马赫数控制方面具有不可比拟的优势,设计风洞拟采用这种形式的二喉道。可调式二喉道又可分为堵块式、调节片加中心体式以及栅指式,不同形式的调节方式决定了它不同的适用性。由于堵块式调节方式结构笨重、调节困难,因此,本文主要对调节片加中心体式和栅指式这两种调节方式进行了研究。
在利用部分算例对采用的数值方法进行验证后,本文分别对调节片式和栅指式二喉道进行了数值计算。首先,为了解调节片式二喉道的收缩段、平直段、扩张段三部段对喉道性能影响的程度大小,本文针对二维情况设计了不同尺寸的模型并对数值模拟的结果进行了讨论。在所给的设计状态中,发现对喉道性能影响最大的是喉道收缩段尺寸。该部段为整个喉道气流速度变化最剧烈的区域。如果长度较短,不利于气流的平缓变化,将会对喉道性能的损失造成较大影响。喉道平直段尺寸和扩张段尺寸在所设计的模型中在损失和效率上影响较小,但是可以得出这两段尺寸适当减小后对喉道效率有利的结论。喉道平直段扩开角和中心体在平直段内的位置也是影响喉道性能两个因素。本文通过平直段取0.5°扩开角的算例验证了适当的扩开角将有助于提高喉道的效率,同时中心体位于不同位置时的算例显示,中心体位置适当后移对喉道性能的提高是有一定作用的。在积累了一定的二维经验后,本文提出了五种以600mm×600mm试验段截面为入口的三维模型,在对数值结果进行处理后,得出了效率较高的尺寸长度。
影响栅指式喉道性能影响因素较多,从翼型的选取到栅指的结构布置已经有详细的经验公式进行参考。本文选取了NACA0025翼型栅指剖面,主要研究了该翼型在不同截尾厚度时对喉道性能影响。为验证喉道翼型的区别,本文选取了一种菱形翼型,比较了钝头翼型和尖头翼型的区别。
根据数值模拟结果,可以发现调节片式喉道的效率普遍高于栅指式,因此本文建议在喉道形式的选取上应当以调节片式为主。
Owing to the need of the continuous transonic/supersonic wind tunnel which is more and more urgent in our Country, the research of 4.8m continuous transonic/supersonic wind tunnel has already begun. In order to ensure that the 4.8m wind tunnel meets the refine request of the wind tunnel experiments and becomes an advanced transonic wind tunnel in the world, its design index of the flow field gives a higher request. As an important section of the wind tunnel, the design of the second throat is one of key techniques of the research about the transonic wind tunnel.
The second throat has already got the extensive application in existing wind tunnel equipments. It can insulate the upstream and downstream flow field resulting in the noise drop of the text section from the downstream and can control the Mach number exactly in the transonic state. When the air passes, the second throat makes use of variational section area to change the speed of the air and coming into being a shock wave of which the Mach number is just greater than 1 in the minimum piece of the second throat. This process induces the choking which becomes the key to control the Mach num exactly in a transonic/supersonic wind tunnel. In the supersonic state, the second throat can improve the efficiency of the wind tunnel notablely. Via reducing the Mach number of the shock wave, the loss of the wind tunnel is reduced and the efficiency of the wind tunnel is improved.
In order to design the second throat which meets the requirement in the method of the numerical simulation, some researches on the second throat of the transonic wind tunnel are carried out in this paper. The second throat can be divided into fixed type and adjustable type. Because of the more advantage of the adjustable type, the designing wind tunnel will use this type. The adjustable type can be divided into type of center chock, type of flap, type of choke finger. The different adjustable ways of the throat have decided the different applicability. The type of center choke has an unwieldy configuration and can’t be regulated easily, so, this paper makes the important point on the type of flap and choke finger.
After validating the numerical method with some standard cases, both the second throat with flap and with choke finger is studied by numerical simulation. Firstly, a group of 2D models are established to study how contraction, straight segment, diffuser influence the performance of second throat. The results indicate that the size of contraction has significant impact on second throat performance. The speed of the air changes the most violently in this section. If the length is shorter, the speed of the air will vary very fast and this section will increase the loss of the throat. The size of the straight segment and the diffuser has less influencing on the loss and the efficiency of the throat, but, it is still can be found out that the seemly shorter length will decrease the loss. The angle of the straight segment and the placement of the center flap in the straight segment are the factors which influence the capability of the throat. Some examples about the 0.5°angle of the straight segment are given in this paper and proves that the angle can improve the efficiency of the throat. Through the examples of the different placement of the center flap in the straight segment, if putting the center flap backward seemly in the straight segment, it has some advantages to improve the efficiency of the throat. Via 2d examples, five models which have the 600mm×600mm test section are designed in this paper which gives the numerical results.
There are many factors which influence the efficiency of throat with choke finger. The aerofoil and configuration of choke finger can be calculated by experiential formulas. In this paper, the NACA0025 aerofoil is chosen for the research. The NACA0025 aerofoil becomes the section of the finger. This paper compares the different bobtail thickness which is an influencing factor to the efficiency of the throat. A rhombus aerofoil is selected in order to get the different influences of aero foils on the throat.
According to the results of the numerical simulation, the flap type is more seemly than the choke finger, so, this type of the throat is advised in this paper.
引文
[1]气动中心四所、二所,4.8m连续式跨超声速风洞建设关键技术研究论证,中国国防科学技术报告,2007年7月。
[2]中国人民解放军总装备部军事训练教材编辑工作委员会,高低速风洞气动设计与结构设计,国防工业出版社, 2003年4月。
[3]廖达雄,陈志强,彭强等,《风洞气动技术若干技术及CFD在风洞设计中的应用初步研究》,气动中心四所国防科学技术报告,1996年12月。
[4]M W Davis, Optimum Windtunnel. AIAA 14th Aerodynamic Testing Conference,1986。
[5]J Prieur, Techincal Excellence and Productivity—The ETW Challenge,1992。
[6]中华人民共和国国家军用标准. GJB1179-91高速风洞低速风洞流场品质规范。
[7]Anderson J.D. Modern Compressible Flow: with Historical Perspective, 3rd ed. New York: McGraw-Hill, 2003.
[8]伍荣林,王振羽,风洞设计原理,北京航空学院出版社,1985年10月。
[9]俞月英,跨声速风洞试验段噪声的试验评价, 1991年3月。
[10]THE EFFICIENCY OF A SECOND THROAT IN STABILIZING THE FLOW IN A TRANSONIC WIND TUNNEL, AIAA 99-3413。
[11]凌其扬,陶祖贤,先进跨声速风洞的设计技术,气动试验与控制测量,1996年9月,第10卷第3期。
[12]Medved B and Eltstrom G.南斯拉夫1.5m三声速下吹式风洞. AIAA第十四届空气动力学实验会议论文集。1986.3
[13]L Vecchione.,R Baldner, The New Italian Transonic Pilot Tunnel。
[14]M ehta R D, The Aerodynamic Design of Blower Tunnels with Wide-angle diffusers, Proog, Aerospace, Sci, 1997,18(1)。
[15]彭强,廖达雄等,《连续式风洞关键技术研究课题论证》,气动中心四所国防科学技术报告,2006年4月。
[16]丛成华,邓小刚,毛枚良,陈吉明.跨音速风洞试验段马赫数精确控制的数值研究.全国航空宇航科学与技术会议,2008.
[17]陈吉明,0.3m×0.3m跨超声速风洞二喉道气动改造设计技术方案,气动中心四所2008年11月。
[18]Burford British Welding Journ, Problems Associated with the design and Construction of wind tunnels, Dec. 1955
[19]John D. Anderson, JR, Fundamentals of Aerodynamics, International Editon 1991.
[20]恽起麟,实验空气动力学,国防工业出版社,1994年10月。
[21] Fluent 6.1 Documentation. USA:FLUENT Inc, 2003.
[22]陈吉明,超音速扩压器激波串现象的数值模拟及工程应用,硕士学位论文,清华大学,2006年5月。
[23]彭强,跨声速风洞扩散段数值模拟,气动中心四所,1996年12月。
[24]彭强,跨声速风洞扩散段三维数值模拟研究论证报告,气动中心四所1995年11月。
[25]徐华舫,空气动力学基础,北京航空学院出版社, 1987年11月。
[26]风洞试验技术,西北工业大学收藏样本,1974年6月。
[27]王新民,风洞第二喉道马赫数控制,硕士学位论文,西北工业大学,1999年。
[27] FL22试验手册.CARDC-4,1991.
[28]中国人民解放军总装备部军事训练教材编辑工作委员会.高速风洞试验.国防工业出版社,2003.
[2]中国人民解放军总装备部军事训练教材编辑工作委员会,高低速风洞气动设计与结构设计,国防工业出版社, 2003年4月。
[3]廖达雄,陈志强,彭强等,《风洞气动技术若干技术及CFD在风洞设计中的应用初步研究》,气动中心四所国防科学技术报告,1996年12月。
[4]M W Davis, Optimum Windtunnel. AIAA 14th Aerodynamic Testing Conference,1986。
[5]J Prieur, Techincal Excellence and Productivity—The ETW Challenge,1992。
[6]中华人民共和国国家军用标准. GJB1179-91高速风洞低速风洞流场品质规范。
[7]Anderson J.D. Modern Compressible Flow: with Historical Perspective, 3rd ed. New York: McGraw-Hill, 2003.
[8]伍荣林,王振羽,风洞设计原理,北京航空学院出版社,1985年10月。
[9]俞月英,跨声速风洞试验段噪声的试验评价, 1991年3月。
[10]THE EFFICIENCY OF A SECOND THROAT IN STABILIZING THE FLOW IN A TRANSONIC WIND TUNNEL, AIAA 99-3413。
[11]凌其扬,陶祖贤,先进跨声速风洞的设计技术,气动试验与控制测量,1996年9月,第10卷第3期。
[12]Medved B and Eltstrom G.南斯拉夫1.5m三声速下吹式风洞. AIAA第十四届空气动力学实验会议论文集。1986.3
[13]L Vecchione.,R Baldner, The New Italian Transonic Pilot Tunnel。
[14]M ehta R D, The Aerodynamic Design of Blower Tunnels with Wide-angle diffusers, Proog, Aerospace, Sci, 1997,18(1)。
[15]彭强,廖达雄等,《连续式风洞关键技术研究课题论证》,气动中心四所国防科学技术报告,2006年4月。
[16]丛成华,邓小刚,毛枚良,陈吉明.跨音速风洞试验段马赫数精确控制的数值研究.全国航空宇航科学与技术会议,2008.
[17]陈吉明,0.3m×0.3m跨超声速风洞二喉道气动改造设计技术方案,气动中心四所2008年11月。
[18]Burford British Welding Journ, Problems Associated with the design and Construction of wind tunnels, Dec. 1955
[19]John D. Anderson, JR, Fundamentals of Aerodynamics, International Editon 1991.
[20]恽起麟,实验空气动力学,国防工业出版社,1994年10月。
[21] Fluent 6.1 Documentation. USA:FLUENT Inc, 2003.
[22]陈吉明,超音速扩压器激波串现象的数值模拟及工程应用,硕士学位论文,清华大学,2006年5月。
[23]彭强,跨声速风洞扩散段数值模拟,气动中心四所,1996年12月。
[24]彭强,跨声速风洞扩散段三维数值模拟研究论证报告,气动中心四所1995年11月。
[25]徐华舫,空气动力学基础,北京航空学院出版社, 1987年11月。
[26]风洞试验技术,西北工业大学收藏样本,1974年6月。
[27]王新民,风洞第二喉道马赫数控制,硕士学位论文,西北工业大学,1999年。
[27] FL22试验手册.CARDC-4,1991.
[28]中国人民解放军总装备部军事训练教材编辑工作委员会.高速风洞试验.国防工业出版社,2003.