JP2013079878A - Method and apparatus for measuring fluid - Google Patents
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Abstract
Description
本発明は、流体の動的特性を測定する方法および装置に関するものであり、特に、自動車や鉄道等の陸上輸送機および航空宇宙分野の風洞実験に適した流体測定方法および装置に関する。 The present invention relates to a method and apparatus for measuring dynamic characteristics of a fluid, and more particularly to a fluid measurement method and apparatus suitable for land transport aircraft such as automobiles and railways and wind tunnel experiments in the aerospace field.
従来、流体の動的特性を測定するものとして、流体に接する物体表面の圧力分布を測定することで流体によりもたらされる圧力場を測定したり、流体内に光学的に発光または散乱光を観察可能な粒子（可視性の粒子）を散布して可視化し、流速や流れ方向等の空間挙動を測定するものが知られている。
例えば、圧力場の測定に関し、流体の圧力に応じた酸素濃度の変化で発光強度が変化する感圧塗料（Pressure-Sensitive paint: PSP）を用いた気流中の非定常圧力場測定が、自動車や鉄道等の陸上輸送機および航空宇宙分野の風洞実験において注目されている。
この測定技術は、感圧塗料に含まれた色素の発光強度が酸素により消光する現象を利用したものである。
高速応答型の感圧塗料と、高速度カメラと高強度レーザ光源を組み合わせることにより、数ｋＨｚのサンプリングレートでの非定常圧力場測定が可能となってきている（例えば特許文献１等参照。）。
Conventionally, to measure the dynamic characteristics of a fluid, it is possible to measure the pressure field caused by the fluid by measuring the pressure distribution on the surface of the object in contact with the fluid, and to observe the emitted or scattered light optically in the fluid It is known that a small particle (visible particle) is dispersed and visualized to measure spatial behavior such as flow velocity and flow direction.
For example, with regard to pressure field measurement, unsteady pressure field measurement in airflow using pressure-sensitive paint (Pressure-Sensitive paint: PSP) whose emission intensity changes with changes in oxygen concentration according to the pressure of the fluid It is attracting attention in land transport aircraft such as railroads and wind tunnel experiments in the aerospace field.
This measurement technique utilizes a phenomenon in which the emission intensity of the dye contained in the pressure-sensitive paint is quenched by oxygen.
By combining a high-speed response type pressure-sensitive paint, a high-speed camera, and a high-intensity laser light source, it has become possible to measure an unsteady pressure field at a sampling rate of several kHz (see, for example, Patent Document 1). .
また、空間挙動の測定に関しても、数１０ｋＨｚのサンプリングレートによる時系列空間流速場の測定が、時系列粒子画像流速測定法（Time-Resolved Particle Image Velocimetry）等により可能となってきている。
この測定技術は、気流中に散布した粒子をレーザとカメラにより可視化し、その移動速度を画像から算出することで気流速度を求める手法である。
この手法も、自動車や鉄道等の陸上輸送機および航空宇宙分野の風洞実験において注目されている。
In addition, regarding the measurement of spatial behavior, it is possible to measure a time-series spatial flow velocity field at a sampling rate of several tens of kHz by a time-series particle image velocity measurement method (Time-Resolved Particle Image Velocimetry) or the like.
This measurement technique is a method for obtaining the airflow velocity by visualizing particles dispersed in the airflow with a laser and a camera and calculating the moving velocity from an image.
This method is also attracting attention in land transport aircraft such as automobiles and railways and in wind tunnel experiments in the aerospace field.
しかしながら、上記のような公知の流体の動的特性の測定技術は、個々に精緻に測定することは可能であるが、圧力場と速度場の両方を測定する場合、感圧塗料により圧力場を測定し、その後に粒子画像流速測定法により速度場を測定するというように、圧力場と速度場を各々別々の試験において測定していた。
すなわち、それぞれの測定は、それぞれ最適化された環境と独自の測定装置で行なう必要があり、同一事象に対して同時に行うことは困難であった。
具体的には、速度場の測定で使用される粒子は、アルコール粒子、油滴粒子、アルミナや二酸化チタンなどの固体粒子に大別されるが、アルコール粒子は感圧塗料を溶かし、油滴粒子は感圧塗料表面に付着し酸素透過性を阻害し、固体粒子は静電気等により感圧塗料に付着し励起光および発光測定を妨げるとともに、感圧塗装面を物理的に破壊するため、これらの粒子の存在下では感圧塗料による圧力場の測定を精度良く行うことはできず、各々別々の試験において測定せざるを得なかった。
However, the known dynamic characteristics measurement techniques of fluids as described above can be precisely measured individually, but when measuring both the pressure field and the velocity field, the pressure field is reduced by pressure-sensitive paint. The pressure field and velocity field were each measured in separate tests, such as measuring and then measuring the velocity field by particle image velocimetry.
In other words, each measurement needs to be performed in an optimized environment and a unique measuring apparatus, and it is difficult to simultaneously perform the same event.
Specifically, the particles used in the velocity field measurement are roughly divided into alcohol particles, oil droplet particles, and solid particles such as alumina and titanium dioxide. The alcohol particles dissolve the pressure-sensitive paint, and the oil droplet particles. Adheres to the pressure-sensitive paint surface and impedes oxygen permeability, and solid particles adhere to the pressure-sensitive paint due to static electricity, etc., preventing excitation light and luminescence measurement, and physically destroying the pressure-sensitive paint surface. In the presence of particles, the pressure field with a pressure-sensitive paint could not be measured with high accuracy, and each test had to be performed separately.
また、可視性の粒子の散布による速度場の測定で使用するレーザ等の光源の投射光および粒子からの散乱光または発光と、感圧塗料による圧力場の測定で使用する感圧塗料に投射する励起光および感圧塗料からの発光がそれぞれ干渉する虞があり、感圧塗料による圧力場の測定と可視性の粒子の散布による速度場の測定の両者で精度が確保できず、同時に行うことが困難な要因となっていた。
そして、別々の試験で得られた圧力場と速度場の測定結果では、時間方向の圧力場と速度場の相関情報を付加情報なしに直接的には得られないことから、特に時間的に変動する現象の流体の動的特性の測定において、圧力場と速度場の因果関係を明確にすることは困難であった。
In addition, the projection light of a light source such as a laser used in the measurement of the velocity field by scattering of visible particles and the scattered light or light emission from the particles and the pressure-sensitive paint used in the measurement of the pressure field by the pressure-sensitive paint are projected. Excitation light and light emission from pressure-sensitive paint may interfere with each other, and accuracy cannot be ensured both in the measurement of the pressure field by pressure-sensitive paint and the velocity field by the dispersion of visible particles. It was a difficult factor.
And in the measurement results of pressure field and velocity field obtained in separate tests, the correlation information of pressure field and velocity field in the time direction cannot be obtained directly without additional information. It was difficult to clarify the causal relationship between the pressure field and the velocity field in the measurement of the dynamic characteristics of the fluid.
そこで、本発明は、感圧塗料による圧力場の測定と可視性の粒子による速度場の測定を、それぞれの測定の精度を損なうことなく同時に行うことを可能とし、時間的に変動する現象であっても、同一事象における複数時刻の時間方向に相関のある圧力場と速度場の情報を取得し、その因果関係を明確にすることを可能とする流体測定方法および装置を提供することを目的とするものである。 Therefore, the present invention is a phenomenon that fluctuates with time by making it possible to simultaneously measure the pressure field using pressure-sensitive paint and the velocity field using visible particles without losing the accuracy of each measurement. However, an object of the present invention is to provide a fluid measurement method and apparatus that can acquire information on pressure fields and velocity fields correlated in the time direction at a plurality of times in the same event and clarify the causal relationship between them. To do.
本請求項１に係る発明は、流体の動的特性を測定する流体測定方法であって、流体に接する物体表面の圧力分布を感圧塗料によって光学的に測定する圧力場測定工程と、流体内に可視性の粒子を散布して流体の空間挙動を光学的に測定する速度場測定工程とを有し、前記感圧塗料を流体の圧力に応じた酸素濃度の変化で発光強度が変化するものとし、前記可視性の粒子を昇華性粒子とし、前記圧力場測定工程および速度場測定工程を同時に行い、同一事象に対する圧力場と速度場の情報を時間方向で相関した情報として取得することにより、前記課題を解決するものである。 The invention according to claim 1 is a fluid measurement method for measuring a dynamic characteristic of a fluid, a pressure field measurement step for optically measuring a pressure distribution on an object surface in contact with the fluid with a pressure sensitive paint, And a velocity field measuring step for optically measuring the spatial behavior of the fluid by spraying visible particles on the pressure-sensitive paint, and the emission intensity of the pressure-sensitive paint changes according to the change of the oxygen concentration according to the pressure of the fluid. The visible particles are sublimable particles, the pressure field measurement step and the velocity field measurement step are performed simultaneously, and information on the pressure field and the velocity field for the same event is obtained as information correlated in the time direction. The problem is solved.
本請求項２に係る発明は、請求項１に係る流体測定方法の構成に加え、前記速度場測定工程における粒子の可視化のための光源の投射光、粒子からの散乱光または発光、前記圧力場測定工程における感圧塗料の励起のための光源の投射光および感圧塗料の発光の、それぞれの光学的干渉の影響を排除する干渉排除工程を有することにより、前記課題を解決するものである。 The invention according to claim 2 includes, in addition to the configuration of the fluid measurement method according to claim 1, projection light of a light source for particle visualization in the velocity field measurement step, scattered light or light emission from particles, and the pressure field. The object is solved by having an interference eliminating step for eliminating the influence of the respective optical interferences of the projection light of the light source for excitation of the pressure sensitive paint and the light emission of the pressure sensitive paint in the measurement step.
本請求項３に係る発明は、請求項２に係る流体測定方法の構成に加え、前記干渉排除工程が、光学フィルタにより行われることにより、前記課題を解決するものである。 In addition to the configuration of the fluid measurement method according to claim 2, the invention according to claim 3 solves the above-described problem by performing the interference elimination step using an optical filter.
本請求項４に係る発明は、請求項２または請求項３に係る流体測定方法の構成に加え、前記干渉排除工程が、前記圧力場測定工程および速度場測定工程の演算処理により行われることにより、前記課題を解決するものである。 In the invention according to claim 4, in addition to the configuration of the fluid measurement method according to claim 2 or claim 3, the interference elimination step is performed by arithmetic processing of the pressure field measurement step and the velocity field measurement step. The above-mentioned problem is solved.
本請求項５に係る発明は、流体の動的特性を測定する流体測定装置であって、流体に接する物体表面に設けられ、流体の圧力に応じた酸素濃度の変化で発光強度が変化する感圧塗料と、流体内に可視性の昇華性粒子を散布する粒子散布手段と、前記感圧塗料に励起用の光を投射する励起光源と、前記感圧塗料の発光を測定する圧力場測定手段と、前記昇華性粒子を可視化するための光を投射する可視化光源と、前記昇華性粒子からの散乱光または発光を測定する速度場測定手段と、前記圧力場測定手段および速度場測定手段の同一事象に対する測定情報を時間方向で相関した情報として取得する情報取得手段とを有することにより、前記課題を解決するものである。 The invention according to claim 5 is a fluid measuring device for measuring the dynamic characteristics of a fluid, and is provided on the surface of an object in contact with the fluid, and the luminescence intensity changes with the change in oxygen concentration according to the pressure of the fluid. Pressure coating, particle spraying means for spraying visible sublimable particles in a fluid, excitation light source for projecting excitation light onto the pressure sensitive paint, and pressure field measuring means for measuring light emission of the pressure sensitive paint And a visualization light source for projecting light for visualizing the sublimable particles, a velocity field measuring means for measuring scattered light or luminescence from the sublimable particles, and the pressure field measuring means and the velocity field measuring means are identical. The problem is solved by including information acquisition means for acquiring measurement information for an event as information correlated in the time direction.
本請求項６に係る発明は、請求項５に係る流体測定装置の構成に加え、前記圧力場測定手段が、前記可視化光源の投射光を直接受光せず、前記速度場測定手段が、前記励起光源の投射光を直接受光しないよう、それぞれ配置され、前記速度場測定手段および圧力場測定手段が、それぞれ観察すべき光以外を低減する光学フィルタを備えていることにより、前記課題を解決するものである。 In the invention according to claim 6, in addition to the configuration of the fluid measurement device according to claim 5, the pressure field measurement unit does not directly receive the projection light of the visualization light source, and the velocity field measurement unit includes the excitation Each of the velocity field measuring means and the pressure field measuring means is provided so as not to directly receive the projection light of the light source, and each of the velocity field measuring means and the pressure field measuring means includes an optical filter for reducing light other than light to be observed. It is.
本請求項１に係る流体測定方法および本請求項５に係る流体測定装置によれば、可視性の粒子を昇華性粒子として圧力場測定および速度場測定を同時に行うことによって、昇華性粒子が感圧塗料に接触すると即座に昇華して気体となるため、感圧塗料を溶かすことがなく、付着することもなく、また、物理的に破壊することもない。
このことで、感圧塗料による圧力場の測定と可視性の粒子による速度場の測定を、それぞれの測定の精度を損なうことなく同時に行うことが可能となり、かつ、時間的に変動する現象であっても、同一事象における複数時刻の時間方向に相関のある圧力場と速度場の情報を取得し、その因果関係を明確にすることができる。
According to the fluid measurement method according to claim 1 and the fluid measurement apparatus according to claim 5, the sublimation particles are sensed by simultaneously performing pressure field measurement and velocity field measurement using the visible particles as sublimation particles. When it comes into contact with the pressure paint, it immediately sublimes and becomes a gas, so that the pressure-sensitive paint does not melt, adhere to it, and does not physically break.
This makes it possible to measure the pressure field with pressure-sensitive paint and the velocity field with visible particles at the same time without losing the accuracy of each measurement, and this is a phenomenon that varies with time. However, it is possible to acquire information on pressure fields and velocity fields correlated in the time direction at a plurality of times in the same event, and clarify the causal relationship.
本請求項２および本請求項６に記載の構成によれば、光学的干渉の影響を排除することで、圧力場測定と速度場測定の両者の精度をさらに向上させて同時に行うことが可能となり、時間的に変動する現象であっても、同一事象における複数時刻の時間方向に相関のある圧力場と速度場の情報を取得し、その因果関係をさらに明確にすることができる。
本請求項３および本請求項６に記載の構成によれば、光学フィルタによって、測定時の干渉排除工程の処理負担を軽くし、正確に光学的干渉の影響を排除することができる。
本請求項４に記載の構成によれば、光学フィルタがない状態あるいは光学フィルタによって排除し切れない光学的干渉の影響を演算処理によって排除することが可能となり、圧力場測定と速度場測定の両者の精度がさらに向上する。
According to the configurations of the second and sixth aspects, by eliminating the influence of optical interference, it is possible to further improve the accuracy of both the pressure field measurement and the velocity field measurement and to perform them simultaneously. Even for a phenomenon that varies with time, it is possible to acquire information on pressure fields and velocity fields correlated in the time direction at a plurality of times in the same event, and further clarify the causal relationship.
According to the configuration of the third and sixth aspects, the optical filter can reduce the processing load of the interference elimination process at the time of measurement, and can accurately eliminate the influence of optical interference.
According to the configuration of the fourth aspect of the present invention, it is possible to eliminate the influence of optical interference in the absence of the optical filter or the optical interference that cannot be completely excluded by the optical filter, by both the pressure field measurement and the velocity field measurement. The accuracy is further improved.
本発明の流体測定方法は、流体の動的特性を測定する流体測定方法であって、流体に接する物体表面の圧力分布を感圧塗料によって光学的に測定する圧力場測定工程と、流体内に可視性の粒子を散布して流体の空間挙動を光学的に測定する速度場測定工程とを有し、前記感圧塗料を流体の圧力に応じた酸素濃度の変化で発光強度が変化するものとし、前記可視性の粒子を昇華性粒子とし、前記圧力場測定工程および速度場測定工程を同時に行い、同一事象に対する圧力場と速度場の情報を時間方向で相関した情報として取得するものであって、感圧塗料による圧力場の測定と可視性の粒子による速度場の測定を、それぞれの測定の精度を損なうことなく同時に行うことを可能とし、時間的に変動する現象であっても、同一事象における複数時刻の時間方向に相関のある圧力場と速度場の情報を取得し、その因果関係を明確にすることを可能とするものであれば、その具体的な実施態様はいかなるものであっても良い。 The fluid measurement method of the present invention is a fluid measurement method for measuring the dynamic characteristics of a fluid, a pressure field measurement step for optically measuring the pressure distribution on the surface of an object in contact with the fluid with a pressure sensitive paint, And a velocity field measuring step for optically measuring the spatial behavior of the fluid by spraying visible particles, and the emission intensity of the pressure-sensitive paint is changed by changing the oxygen concentration according to the pressure of the fluid. The visible particle is a sublimable particle, the pressure field measurement step and the velocity field measurement step are simultaneously performed, and information on the pressure field and the velocity field for the same event is acquired as information correlated in the time direction. It is possible to measure the pressure field with pressure-sensitive paint and the velocity field with visible particles at the same time without impairing the accuracy of each measurement. Multiple times in The acquired information of time pressure field and velocity field having a correlation with the direction, as long as it enables to clarify the causal relationship, specific embodiments thereof may be any one.
本発明の流体測定装置は、流体の動的特性を測定する流体測定装置であって、流体に接する物体表面に設けられ、流体の圧力に応じた酸素濃度の変化で発光強度が変化する感圧塗料と、流体内に可視性の昇華性粒子を散布する粒子散布手段と、前記感圧塗料に励起用の光を投射する励起光源と、前記感圧塗料の発光を測定する圧力場測定手段と、前記昇華性粒子を可視化するための光を投射する可視化光源と、前記昇華性粒子からの散乱光または発光を測定する速度場測定手段と、前記圧力場測定手段および速度場測定手段の同一事象に対する測定情報を時間方向で相関した情報として取得する情報取得手段とを有するものであって、感圧塗料による圧力場の測定と可視性の粒子による速度場の測定を、それぞれの測定の精度を損なうことなく同時に行うことを可能とし、時間的に変動する現象であっても、同一事象における複数時刻の時間方向に相関のある圧力場と速度場の情報を取得し、その因果関係を明確にすることを可能とするものであれば、その具体的な実施態様はいかなるものであっても良い。 The fluid measuring device of the present invention is a fluid measuring device that measures the dynamic characteristics of a fluid, and is provided on the surface of an object in contact with the fluid. A coating material; particle spraying means for spraying visible sublimable particles in the fluid; an excitation light source for projecting light for excitation onto the pressure sensitive paint; and a pressure field measuring means for measuring light emission of the pressure sensitive paint. A visualizing light source that projects light for visualizing the sublimable particles, a velocity field measuring unit that measures scattered light or luminescence from the sublimable particles, and the same event of the pressure field measuring unit and the velocity field measuring unit Information acquisition means for acquiring measurement information on the time as a correlated information in the time direction, and measuring the pressure field with pressure-sensitive paint and the velocity field with visible particles, Not to lose It is possible to perform simultaneously, even if the phenomenon fluctuates in time, to acquire information on pressure and velocity fields correlated in the time direction of multiple times in the same event, and to clarify the causal relationship As long as it is possible, the specific embodiment may be any.
本発明に係る流体測定方法および流体測定装置の一実施態様を説明する。
流体測定装置１００は、図１に概略的に示すように、矩形ダクト１０１の一方の端部にバルブ１０３を介して吸引手段１０２を接続し、他方の端部に粒子供給容器１０８を介して気流形成ノズル１０４を接続して、矩形ダクト１０１内を測定すべき流体の圧力場と速度場を形成する風洞とするように構成されている。
気流形成ノズル１０４には気体供給手段１０５から測定すべき流体となる気体が供給されるとともに、気流形成ノズル１０４の上流に設けられた粒子供給容器１０８には粒子散布ノズル１０７が設けられ、通過する気体に速度場を光学的に測定するための昇華性粒子１３１が散布される。散布される昇華性粒子１３１は、粒子供給タンク１０６から供給される。
An embodiment of a fluid measuring method and a fluid measuring device according to the present invention will be described.
As schematically shown in FIG. 1, the fluid measuring device 100 has a suction means 102 connected to one end of a rectangular duct 101 via a valve 103 and an air flow via a particle supply container 108 to the other end. The formation nozzle 104 is connected to form a wind tunnel that forms a pressure field and a velocity field of the fluid to be measured in the rectangular duct 101.
A gas as a fluid to be measured is supplied from the gas supply means 105 to the air flow forming nozzle 104, and a particle distribution nozzle 107 is provided in the particle supply container 108 provided upstream of the air flow forming nozzle 104 and passes therethrough. The gas is sprayed with sublimable particles 131 for optically measuring the velocity field. The sublimable particles 131 to be dispersed are supplied from the particle supply tank 106.
矩形ダクト１０１は、少なくとも隣接する２面がアクリル樹脂等の透明の材質で形成され、少なくとも対向面と隣接面が透明である面の内面側には感圧塗料１１１が塗布されている。
矩形ダクト１０１の外部周囲には、感圧塗料１１１に励起用の光を矩形ダクト１０１内に投射する励起光源１１３、感圧塗料１１１の発光を測定する圧力場測定手段である高速度カメラ１１２、昇華性粒子１３１を可視化するための光を矩形ダクト１０１内に投射する可視化光源１２１、昇華性粒子１３１からの散乱光または発光を測定する速度場測定手段である高速度カメラ１２２が配されている。
励起光源１１３、圧力場測定手段である高速度カメラ１１２および速度場測定手段である高速度カメラ１２２は、図１（ｂ）に示すように、感圧塗料１１１が塗布された面と対向する透明な面の外側に配置され、可視化光源１２１は、図１（ａ）に示すように、感圧塗料１１１が塗布された面と隣接する透明な面の外側に配置されている。
In the rectangular duct 101, at least two adjacent surfaces are formed of a transparent material such as acrylic resin, and a pressure-sensitive paint 111 is applied to the inner surface side of the surface where at least the opposing surface and the adjacent surface are transparent.
Around the outside of the rectangular duct 101, an excitation light source 113 that projects excitation light into the rectangular duct 101 on the pressure-sensitive paint 111, a high-speed camera 112 that is a pressure field measuring unit that measures light emission of the pressure-sensitive paint 111, A visualization light source 121 that projects light for visualizing the sublimable particles 131 into the rectangular duct 101, and a high-speed camera 122 that is a velocity field measuring unit that measures scattered light or light emission from the sublimable particles 131 are arranged. .
As shown in FIG. 1B, the excitation light source 113, the high-speed camera 112 that is the pressure field measuring means, and the high-speed camera 122 that is the speed field measuring means are transparent facing the surface on which the pressure-sensitive paint 111 is applied. As shown in FIG. 1A, the visualization light source 121 is disposed outside a transparent surface adjacent to the surface to which the pressure-sensitive paint 111 is applied.
圧力場測定工程は、測定対象に想定される非定常現象の周波数よりも十分に高速応答かつ十分な発光量を生じさせうる感圧塗料１１１と、十分な空間解像度を持ち時系列に連続に多数の画像を取得することが可能な高速度カメラ１１２からなる圧力場測定手段と、高速応答型の感圧塗料１１１に含まれる感圧色素の吸収線波長を含む十分に励起光量の大きい励起光源１１３とを用いる。
感圧塗料１１１の発光と励起光源１１３が投射する感圧塗料１１１の励起光は、それぞれ光学的に分離可能な光とし、かつ、後述する速度場測定工程で使用する可視化光源１２１の投射光と昇華性粒子１３１からの散乱光または発光とも光学的に分離可能な光とする。
高速度カメラ１１２には、感圧塗料１１１からの発光以外の光を除去する光学フィルタ１１４を設置し、感圧塗料１１１の発光を選択的に取得するとともに、速度場測定工程に起因する光の影響を除去する。
The pressure field measurement process consists of a pressure-sensitive paint 111 that can generate a sufficient amount of light emission and a sufficiently high-speed response than the frequency of the unsteady phenomenon assumed for the measurement object, and a large number of continuous time series with sufficient spatial resolution. A pressure field measuring unit comprising a high-speed camera 112 capable of acquiring a high-speed camera 112 and an excitation light source 113 having a sufficiently large excitation light amount including the absorption line wavelength of the pressure-sensitive dye contained in the high-speed response type pressure-sensitive paint 111. And are used.
The light emission of the pressure-sensitive paint 111 and the excitation light of the pressure-sensitive paint 111 projected by the excitation light source 113 are optically separable lights, respectively, and the projection light of the visualization light source 121 used in the velocity field measurement process described later. Light that is optically separable from scattered light or emitted light from the sublimable particles 131 is used.
The high-speed camera 112 is provided with an optical filter 114 that removes light other than light emitted from the pressure-sensitive paint 111, and selectively obtains light emitted from the pressure-sensitive paint 111, and emits light from the speed field measurement process. Remove the effect.
これらの手段を用いて、静的かつ既知の圧力場の複数条件について、感圧塗料１１１を施した測定対象発光画像を取得し、既知の圧力情報と、取得した発光画像の関係を使用することで、測定対象とする感圧塗料１１１の圧力測定のための校正式を得る。
感圧塗料１１１の吸収する波長域に、速度場測定工程の可視化光源１２１または粒子１３１からの散乱光または発光の波長が存在する場合は、これらの光を測定時と同一または可能な範囲で類似の条件で発生させ、測定対象とする感圧塗料１１１の圧力測定のための校正式および基準画像を得る。
Using these means, obtain a measurement object luminescent image with pressure-sensitive paint 111 for multiple conditions of static and known pressure fields, and use the relationship between the known pressure information and the acquired luminescent image. Thus, a calibration formula for measuring the pressure of the pressure-sensitive paint 111 to be measured is obtained.
When the wavelength of light absorbed by the visualization light source 121 or the particle 131 in the velocity field measurement process is present in the wavelength range absorbed by the pressure-sensitive paint 111, these lights are the same or similar within the range possible. The calibration equation and the reference image for measuring the pressure of the pressure-sensitive paint 111 to be measured are obtained.
速度場測定工程は、流体現象が変化しないと仮定できる程度に極短時間の時間間隔で連続的に２発以上の照射が可能であり、かつ測定対象に想定される非定常現象の周波数よりも十分に高周波でその２発一組のレーザ照射を連続的に可能で、かつ十分な輝度を有する高繰り返しレーザ照射によってシート状のレーザ照射光を形成可能なレーザ発振手段からなる可視化光源１２１を用い、投射されるレーザ照射光により測定対象領域を気流と共に通過する昇華性粒子１３１を照射する。
照射されたレーザ照射光の粒子１３１からの散乱光または発光は、十分な空間解像度を持ち、時系列に連続に多数の画像を取得でき、かつ高繰り返しレーザと同期を取ることが可能な高速度カメラ１２２からなる速度場測定手段を用いて撮影する。
粒子１３１を照射するレーザ光および昇華性粒子１３１からの散乱光または発光は、励起光源１１３が投射する感圧塗料１１１の励起光および感圧塗料１１１の発光と光学的に分離可能なものとする。
In the velocity field measurement process, it is possible to irradiate two or more shots continuously in an extremely short time interval to the extent that it can be assumed that the fluid phenomenon does not change, and the frequency of the unsteady phenomenon assumed for the measurement object. A visualization light source 121 comprising a laser oscillation means capable of continuously forming a pair of laser irradiations at a sufficiently high frequency and capable of forming a sheet-like laser irradiation light by a high repetition laser irradiation having a sufficient luminance is used. The sublimable particles 131 that pass through the measurement target region together with the airflow are irradiated by the projected laser irradiation light.
The scattered light or light emission from the particles 131 of the irradiated laser irradiation light has sufficient spatial resolution, can acquire a large number of images continuously in time series, and can be synchronized with a high repetition laser at high speed. Photographing is performed using a velocity field measuring unit comprising the camera 122.
The laser light irradiating the particles 131 and the scattered light or light emission from the sublimable particles 131 are optically separable from the excitation light of the pressure-sensitive paint 111 and the light emission of the pressure-sensitive paint 111 projected by the excitation light source 113. .
高速度カメラ１２２には、昇華性粒子１３１の散乱光または発光以外を除去する光学フィルタ１２３を設置し、昇華性粒子１３１の散乱光または発光を選択的に取得する。
気流中に散布される昇華性粒子１３１は、感圧塗料１１１の表面を汚染せず、圧力場測定工程を妨げないドライアイス等の粒子を用いる。
昇華性粒子１３１の供給および散布においては、単一系統または複数系統の供給系を使用する。粒子散布ノズル１０７は、昇華性粒子１３１の直径を変更可能とし、かつ一様な昇華性粒子１３１の散布を可能とする単一孔または多孔を有するものとする。
The high-speed camera 122 is provided with an optical filter 123 that removes light other than the scattered light or light emission of the sublimable particles 131 and selectively acquires the scattered light or light emission of the sublimable particles 131.
As the sublimable particles 131 dispersed in the air stream, particles such as dry ice that do not contaminate the surface of the pressure-sensitive paint 111 and do not interfere with the pressure field measurement process are used.
In supplying and spraying the sublimable particles 131, a single system or a plurality of systems are used. It is assumed that the particle spray nozzle 107 has a single hole or a hole that enables the diameter of the sublimable particles 131 to be changed and allows the uniform sublimable particles 131 to be sprayed.
昇華性粒子１３１の一部が気流中で昇華し、測定対象とする気流の物理条件が変化する場合に備えて、気流の総温、総圧、組成、音速などの物理量を測定可能とする測定系を設置し、これらの物理量を測定し、気流条件の変化量を測定後に補正可能とする。
測定対象となる気流は、昇華性粒子１３１を使用することによる気流変化の影響をあらかじめ予測でき、かつ、その影響を最小とするように水分の凝縮の影響を抑制できる乾燥気体を使用する。
この乾燥気体は、組成変化による流体物理量の影響を考慮し、レイノルズ数およびマッハ数等の目的とする流体現象を支配する無次元数を目的の条件と同一または類似とする気体組成、総温および総圧を有する混合気体であり、気体供給手段１０５に蓄えられ、あるいは生成される。
Measurement that enables measurement of physical quantities such as total temperature, total pressure, composition, and sound velocity of airflow in preparation for the case where some of the sublimable particles 131 sublimate in the airflow and the physical conditions of the airflow to be measured change. The system is installed, these physical quantities are measured, and the change in airflow conditions can be corrected after measurement.
As the air flow to be measured, a dry gas that can predict in advance the influence of the air flow change caused by using the sublimable particles 131 and can suppress the influence of moisture condensation so as to minimize the influence is used.
In consideration of the influence of fluid physical quantities due to composition changes, this dry gas has a gas composition, total temperature, and temperature that have the same or similar dimensionless numbers that govern the target fluid phenomenon such as Reynolds number and Mach number. It is a mixed gas having a total pressure, and is stored or generated in the gas supply means 105.
次に、本発明に係る流体測定方法および流体測定装置の具体的な一実施例について以下に説明する。
＜測定対象＞
図２に示すような擬似衝撃波と呼ばれる超音速流中の衝撃波群を対象として、壁面圧力場と空間速度場を測定した。矩形ダクト１０１の一面を感圧塗料１１１にて塗装し、圧力場を測定した。圧力場を測定した壁面と平行であり、かつ、矩形ダクト１０１の中央を通る断面を対象として速度場を測定した。
Next, a specific example of the fluid measuring method and the fluid measuring apparatus according to the present invention will be described below.
<Measurement target>
The wall pressure field and space velocity field were measured for a shock wave group in a supersonic flow called a pseudo shock wave as shown in FIG. One surface of the rectangular duct 101 was painted with a pressure-sensitive paint 111, and the pressure field was measured. The velocity field was measured for a cross section parallel to the wall surface where the pressure field was measured and passing through the center of the rectangular duct 101.
＜実験装置＞
本実施例の、非定常感圧塗料測定と時系列粒子画像流速測定を同時に行ったシステムにおいては、図１に示す上述した一実施態様の流体測定装置１００の、気体供給手段１０５としてエアーバック、気流形成ノズル１０４として超音速ノズル、吸引手段１０２として真空タンクを用いた。
粒子供給タンク１０６を二酸化炭素ボンベとし、粒子散布ノズル１０７から散布される昇華性粒子１３１をドライアイスの微粉末とした。
最上流のエアーバックは、乾燥空気を充填するためのものである。湿り空気を使用する場合、ドライアイス供給時に、湿り空気中の水分が凝縮し測定の妨げとなることから、乾燥空気を使用した。粒子供給容器１０８には、２系統の粒子供給系を設置した。超音速ノズルは設計マッハ数が２．０である。
<Experimental equipment>
In the system of the present embodiment in which unsteady pressure-sensitive paint measurement and time-series particle image flow velocity measurement were simultaneously performed, an air bag as the gas supply unit 105 of the fluid measurement device 100 of the above-described embodiment illustrated in FIG. A supersonic nozzle was used as the airflow forming nozzle 104, and a vacuum tank was used as the suction means 102.
The particle supply tank 106 was a carbon dioxide cylinder, and the sublimable particles 131 sprayed from the particle spray nozzle 107 were fine powder of dry ice.
The most upstream air bag is for filling with dry air. When humid air was used, dry air was used because moisture in the humid air was condensed during the supply of dry ice, which hindered measurement. Two particle supply systems were installed in the particle supply container 108. The supersonic nozzle has a design Mach number of 2.0.
測定部の矩形ダクト１０１の上板は金属製であり、底板と２枚の側板のうちカメラ側の１枚は透明アクリル製である。残りの側板は金属製とし、内面側に高速応答型の多孔質タイプの感圧塗料１１１を塗装した。
下流のバルブ１０３は手動式のバタフライバルブである。このバルブ１０３を開けることで、エアーバック中の乾燥空気および供給したドライアイスが超音速ノズルを通過して加速される。加速された気流は、測定部の矩形ダクト１０１を通過して真空タンクに吸い込まれる。
The upper plate of the rectangular duct 101 of the measurement unit is made of metal, and one of the bottom plate and the two side plates on the camera side is made of transparent acrylic. The remaining side plates were made of metal, and a high-speed response type porous pressure-sensitive paint 111 was coated on the inner surface side.
The downstream valve 103 is a manual butterfly valve. By opening the valve 103, the dry air in the air bag and the supplied dry ice are accelerated through the supersonic nozzle. The accelerated airflow passes through the rectangular duct 101 of the measurement unit and is sucked into the vacuum tank.
＜感圧塗料測定系＞
感圧塗料測定系は、上述の感圧塗料１１１の塗装面に加え、励起光源１１３と圧力場測定手段である高速度カメラ１１２より構成される。
感圧塗料１１１の塗装面は、以下のように製作した。使用した板材はＡｌ−Ｍｇ合金（A5052）である。この板材を陽極として、酸性電解液（硫酸、シュウ酸、リン酸）中で通電した。このようにして、表面をアルマイト加工することで、板材表面に陽極酸化アルミニウム皮膜を形成した。陽極酸化処理後、模型表面の水和物を除去するために、板材をリン酸溶液中に浸漬した。さらに、リン酸を取り除くために、蒸留水への浸漬を数度行った。感圧塗料色素には、［Ｒｕ（ｄｐｐ）３］２＋を使用し、ジクロロメタンを溶媒として、感圧塗料色素を含む溶液を作成した。上記の処理を施した板材をこの感圧塗料色素を含む溶液に浸漬することで、感圧塗料色素を板材に吸着させた。乾燥させた後、ステアリン酸をヘキサンに溶かした溶液に、感圧色素を吸着させた板材を浸漬することで疎水化処理を施した。
<Pressure sensitive paint measuring system>
The pressure-sensitive paint measurement system includes an excitation light source 113 and a high-speed camera 112 as pressure field measurement means in addition to the above-described painted surface of the pressure-sensitive paint 111.
The coated surface of the pressure sensitive paint 111 was manufactured as follows. The used plate material is an Al-Mg alloy (A5052). Using this plate material as an anode, current was passed in an acidic electrolyte (sulfuric acid, oxalic acid, phosphoric acid). In this way, an anodized aluminum film was formed on the surface of the plate material by anodizing the surface. After the anodizing treatment, the plate material was immersed in a phosphoric acid solution in order to remove the hydrate on the model surface. Furthermore, in order to remove phosphoric acid, it was immersed in distilled water several times. [Ru (dpp) 3 ] 2+ was used as the pressure-sensitive paint dye, and a solution containing the pressure-sensitive paint dye was prepared using dichloromethane as a solvent. The plate material subjected to the above treatment was immersed in a solution containing the pressure-sensitive paint pigment, thereby adsorbing the pressure-sensitive paint pigment on the plate material. After drying, a hydrophobization treatment was performed by immersing the plate material on which the pressure-sensitive dye was adsorbed in a solution of stearic acid in hexane.
励起光源１１３には、後述する粒子画像流速測定法で使用する光源とは異なる波長の光を使用した。感圧塗料測定用の励起光源１１３は、発光波長が４５０から４５５ｎｍである半導体レーザを使用した。リキッドライトガイドに接続された照射器から、測定部である矩形ダクト１０１の側壁の透明アクリル窓を通して感圧塗料１１１の塗装された壁面を照射した。
感圧塗料１１１からの発光を測定する高速度カメラ１１２は、レンズ（Nikkor 50 mm f/1.2、Nikon）を装着したＣＭＯＳ高速度カメラ（Phantom V7.3、 Vision research）を用い、感圧塗料１１１の発光以外の光を除去するための光学フィルタ１１４として、バンドパスフィルタ（O58フィルタ）をレンズ前面に取り付けた。
As the excitation light source 113, light having a wavelength different from that of the light source used in the particle image velocimetry described later is used. As the excitation light source 113 for pressure-sensitive paint measurement, a semiconductor laser having an emission wavelength of 450 to 455 nm was used. From the irradiator connected to the liquid light guide, the wall surface coated with the pressure-sensitive paint 111 was irradiated through the transparent acrylic window on the side wall of the rectangular duct 101 serving as the measurement unit.
The high-speed camera 112 that measures light emission from the pressure-sensitive paint 111 uses a CMOS high-speed camera (Phantom V7.3, Vision research) equipped with a lens (Nikkor 50 mm f / 1.2, Nikon). A band pass filter (O58 filter) was attached to the front surface of the lens as an optical filter 114 for removing light other than the above light emission.
＜粒子画像流速測定系＞
粒子画像流速測定系は、昇華性粒子１３１としてドライアイス粒子をトレーサ粒子とする粒子供給系、トレーサ粒子を可視化するためのシート状のレーザ照射光を投射するレーザシート系、トレーサ粒子からの散乱光または発光を測定する速度場測定手段である高速度カメラ１２２より構成される。
粒子供給系は、粒子供給タンク１０６である液化二酸化炭素ボンベ、粒子供給容器１０８、粒子散布ノズル１０７より構成した。
粒子散布ノズル１０７は、図３に示すように、微小孔１３４を有する噴射器１３２および該噴射器１３２下流部の金属管１３３より構成される。本実施例では、液化二酸化炭素を直径１ｍｍの微小孔１３４より噴射させることでドライアイス粒子を供給した。直径１ｍｍの微小孔１３４の下流には、多数の側孔１３５を有する金属管１３３を設置した。この金属管１３３を設置することにより、ドライアイス粒子の成長を促すことができ、また、気流へ一様に散布することも可能となる。
<Particle image flow velocity measurement system>
The particle image flow velocity measurement system includes a particle supply system using dry ice particles as tracer particles as sublimable particles 131, a laser sheet system for projecting sheet-shaped laser irradiation light for visualizing the tracer particles, and scattered light from the tracer particles. Or it is comprised from the high speed camera 122 which is a speed field measurement means which measures light emission.
The particle supply system was configured by a liquefied carbon dioxide cylinder as a particle supply tank 106, a particle supply container 108, and a particle spray nozzle 107.
As shown in FIG. 3, the particle spray nozzle 107 includes an injector 132 having a minute hole 134 and a metal tube 133 downstream of the injector 132. In this example, dry ice particles were supplied by injecting liquefied carbon dioxide from the micro holes 134 having a diameter of 1 mm. A metal tube 133 having a large number of side holes 135 was installed downstream of the minute holes 134 having a diameter of 1 mm. By installing this metal tube 133, it is possible to promote the growth of dry ice particles, and it is possible to uniformly disperse it in the air current.
レーザシート系の可視化光源１２１には、感圧塗料１１１の発光波長とは異なる５３２ｎｍの高繰り返しダブルパルスネオジムヤグ（Nd:YAG）レーザ（１０ｋＨｚ時の定格出力１０ｍＪ／ｐｕｌｓｅ、LDP-200MQG DUAL DIODE PUMPED LASER、LEE LASER）を使用した。本可視化光源１２１は、２つのレーザヘッドを有し、それぞれのレーザヘッドより短い時間間隔でレーザ光を照射することで、短い時間間隔で２発のレーザ光を照射することができる。シリンドリカルレンズを含むレンズ系によりシート状のレーザ照射光を形成し、透明アクリルである矩形ダクト１０１の底板より照射した。
シート状のレーザ照射光によって照射されるドライアイス粒子からの散乱光を測定する高速度カメラ１２２は、レンズ（Nikkor 105mm f/2、 Nikon）を装着したＣＭＯＳ高速度カメラ（Phantom V710、 Vision research）を用いた。
レンズ前面に、感圧塗料１１１測定の励起光および発光を除去するための光学フィルタ１２３として、干渉フィルタ（５３２ｎｍ透過）を装着しドライアイス粒子からの散乱光を選択的に高速度カメラ１２２にて撮影した。
The laser sheet-based visualization light source 121 includes a 532 nm high repetitive double pulse neodymium yag (Nd: YAG) laser (rated output of 10 mJ / pulse at 10 kHz, LDP-200MQG DUAL DIODE PUMPED), which is different from the emission wavelength of the pressure sensitive paint 111 LASER, LEE LASER) were used. The visualization light source 121 has two laser heads, and can irradiate two laser beams at a short time interval by irradiating the laser beam at a shorter time interval than each laser head. Sheet-shaped laser irradiation light was formed by a lens system including a cylindrical lens, and was irradiated from the bottom plate of the rectangular duct 101 made of transparent acrylic.
The high-speed camera 122 that measures the scattered light from the dry ice particles irradiated by the sheet-like laser light is a CMOS high-speed camera (Phantom V710, Vision research) equipped with a lens (Nikkor 105mm f / 2, Nikon). Was used.
An interference filter (532 nm transmission) is mounted on the front surface of the lens as an optical filter 123 for removing excitation light and light emission of the pressure-sensitive paint 111 measurement, and scattered light from dry ice particles is selectively selected by the high-speed camera 122. I took a picture.
＜同期システム＞
図４に、感圧塗料測定系（ＰＳＰ）と粒子画像流速測定系（ＰＩＶ）の同期システムの概略図を示す。
粒子画像流速測定法は、その方式が複数存在し、方式ごとに、カメラとレーザの同期方法が異なるが、本実施例では、１フレームに１露光となる連続した２フレームを撮影する方式で粒子画像を撮影した。信号発生器である高速度カメラ同期信号装置（High speed controller）より、４系統の信号を発生する。
１系統目は、粒子画像流速測定システムの１時刻目のレーザに向かう信号（Ｑ１）である。この信号は、途中遅延信号発生器（ＤＧ５３５）において２系統に分岐される。遅延発生器より分岐された１系統は遅延されることなくＬａｓｅｒ１に入力される。残りの１系統には、遅延信号発生器により遅延された信号を出力する。この遅延された信号は、感圧塗料測定用のカメラの同期信号として入力される。
高速度カメラ同期信号装置より出力される２系統目（Ｑ２）は、直接Ｌａｓｅｒ２に入力される。高速度カメラ同期信号装置より出力される２系統（Ｑ１、Ｑ２）により、２発で一組のレーザの発振間隔は設定される。
<Synchronous system>
FIG. 4 shows a schematic diagram of a synchronized system of a pressure sensitive paint measurement system (PSP) and a particle image flow velocity measurement system (PIV).
There are a plurality of particle image velocimetry methods, and the synchronization method of the camera and the laser is different for each method. In this embodiment, the particle image velocimetry is a method of capturing two consecutive frames, one exposure per frame. An image was taken. Four systems of signals are generated from a high speed camera synchronization signal device (High speed controller) which is a signal generator.
The first system is a signal (Q1) directed to the laser at the first time of the particle image velocimetry system. This signal is branched into two systems in the midway delay signal generator (DG535). One system branched from the delay generator is input to Laser 1 without being delayed. A signal delayed by the delay signal generator is output to the remaining one system. This delayed signal is input as a synchronization signal of the camera for pressure sensitive paint measurement.
The second system (Q2) output from the high-speed camera synchronization signal device is directly input to Laser2. Two lasers (Q1, Q2) output from the high-speed camera synchronization signal device set the oscillation interval of one set of lasers.
高速度カメラ同期信号装置より出力される３系統目（ｃａｍ１）は、粒子画像流速測定法用カメラの同期信号として入力される。この３系統（Ｑ１、 Ｑ２、 ｃａｍ１）により、粒子画像流速測定法用カメラとレーザの同期が取られる。また、遅延発生器より分岐した感圧塗料測定用カメラに向かう遅延信号とこれら３系統（Ｑ１、 Ｑ２、 ｃａｍ１）により、粒子画像流速測定系と感圧塗料測定系の同期が取られる。
高速度カメラ同期信号装置より出力される４系統目（Trigger）は、測定開始のタイミングを入力する信号である。実施例では、試験部の圧力値をトリガーとするために、圧力測定系の電圧信号を基準として信号発生器（Pulse Generator）よりトリガー信号を発生させ、その信号と元に、高速度カメラ同期信号装置より測定開始のトリガー信号を発生した。これらの信号は３分岐され、１系統は粒子画像流速測定用カメラに、１系統は感圧塗料測定用カメラに、最後の１系統は記録用としてデータ記録用ロガー（WE7000）に送られる。
The third system (cam1) output from the high-speed camera synchronization signal device is input as a synchronization signal of the particle image velocimetry camera. The three systems (Q1, Q2, cam1) synchronize the particle image velocimetry camera with the laser. In addition, the particle image flow velocity measurement system and the pressure-sensitive paint measurement system are synchronized with each other by a delay signal directed to the pressure-sensitive paint measurement camera branched from the delay generator and these three systems (Q1, Q2, cam1).
The fourth system (Trigger) output from the high-speed camera synchronization signal device is a signal for inputting the measurement start timing. In the embodiment, in order to use the pressure value of the test section as a trigger, a trigger signal is generated from a signal generator (Pulse Generator) based on the voltage signal of the pressure measurement system, and the high-speed camera synchronization signal is based on that signal. A trigger signal for starting measurement was generated from the device. These signals are branched into three, one line is sent to the particle image flow velocity measuring camera, one line is sent to the pressure sensitive paint measuring camera, and the last one line is sent to the data recording logger (WE7000) for recording.
感圧塗料測定用カメラと粒子画像流速測定用カメラの撮影画像は、イーサネット（登録商標）ケーブルを介してそれぞれの測定用ＰＣに送られる。
図５は、上述の同期システムによって実現した感圧塗料測定カメラ（ＰＳＰ ＣＡＭＥＲＡ）と粒子画像流速測定用カメラ（ＰＩＶ ＣＡＭＥＲＡ）と２台のレーザ（ＬＡＳＥＲ１、ＬＡＳＥＲ２）の同期タイミングを示している。線の立ち上がっている時間が、カメラに関しては露光時間を表し、レーザに関しては発光している時間を表す。
The captured images of the pressure-sensitive paint measurement camera and the particle image flow velocity measurement camera are sent to each measurement PC via an Ethernet (registered trademark) cable.
FIG. 5 shows the synchronization timing of the pressure-sensitive paint measurement camera (PSP CAMERA), the particle image flow velocity measurement camera (PIV CAMERA), and the two lasers (LASER1, LASER2) realized by the above-described synchronization system. The rise time of the line represents the exposure time for the camera, and the light emission time for the laser.
＜感圧塗料測定校正方法およびデータ処理方法＞
感圧塗料測定の校正係数の導出は以下の手順で行った。まず、励起光および照明のない状態にて感圧塗料塗装面の画像を撮影する。これをダーク画像と呼ぶ。その後、測定部の圧力を１０ｋＰａ間隔で真空ポンプおよび乾燥空気により変化させる。それぞれの圧力条件下において、励起光源を照射し、感圧塗料塗装面の発光画像を撮影する。これを１０ｋＰａから大気圧までの約１０点について行う。
撮影した発光画像から、ダーク画像を減じ、ノイズ成分の除去を行う。ダーク画像を減じた各圧力下の発光画像群を平均化処理する。これら平均発光画像の大気圧状態（Ｐｒｅｆ）の発光強度画像を基準発光強度画像（Ｉｒｅｆ）とする。各圧力時の平均の発光強度画像（Ｉ）で基準発光強度画像（Ｉｒｅｆ）を除し、両者の強度比画像（Ｉｒｅｆ／Ｉ）を得る。得られた感圧塗料発光強度画像と測定時の圧力データを利用し、校正係数の算出を行う。各発光強度画像とダーク画像は、２００枚の画像を取得し平均化することで得た。発光強度比と圧力の関係は、スタン−ボルマー（Ｓｔｅｒｎ−Ｖｏｌｍｅｒ）式で表される。校正においては、スタン−ボルマー式を圧力について変形した式の係数部を校正時の既知の圧力と発光強度比から求めた。測定においては、発光強度比を測定し、発行強度比から変形した式に基づき圧力場を求めた。
校正式を得る行程を図６に示す。本実施例においては、測定部内での校正係数のばらつきも考慮し、図６の行程に基づき、一定領域ごとに校正係数を求めた。
<Pressure-sensitive paint measurement calibration method and data processing method>
The calibration coefficient for pressure sensitive paint measurement was derived by the following procedure. First, an image of the pressure-sensitive paint painted surface is taken without excitation light and illumination. This is called a dark image. Thereafter, the pressure of the measurement unit is changed by a vacuum pump and dry air at intervals of 10 kPa. Under each pressure condition, an excitation light source is irradiated and a light emission image of the pressure-sensitive paint coating surface is taken. This is performed for about 10 points from 10 kPa to atmospheric pressure.
The dark image is subtracted from the photographed emission image to remove noise components. The light emission image group under each pressure reduced from the dark image is averaged. The emission intensity image of the average emission image in the atmospheric pressure state (P ref ) is defined as a reference emission intensity image (I ref ). The reference emission intensity image (I ref ) is divided by the average emission intensity image (I) at each pressure to obtain an intensity ratio image (I ref / I) of both. Using the obtained pressure-sensitive paint emission intensity image and pressure data at the time of measurement, a calibration coefficient is calculated. Each emission intensity image and dark image were obtained by acquiring and averaging 200 images. The relationship between the emission intensity ratio and the pressure is represented by a Stan-Volmer equation. In the calibration, a coefficient part of a formula obtained by modifying the Stan-Volmer formula with respect to the pressure was obtained from the known pressure and the emission intensity ratio at the time of calibration. In the measurement, the light emission intensity ratio was measured, and the pressure field was obtained based on an equation modified from the issued intensity ratio.
The process of obtaining the calibration formula is shown in FIG. In the present embodiment, the calibration coefficient is obtained for each fixed region based on the process of FIG. 6 in consideration of the variation of the calibration coefficient in the measurement unit.
測定においては、まず、大気圧下で、ダーク画像、基準発光強度画像（Ｉｒｅｆ）を撮影した。粒子画像流速測定で使用するレーザ光が、感圧塗料の吸収帯域に入ることから、基準発光強度画像を撮影する際には、感圧塗料測定の励起光に加え、粒子画像流速測定のシート状のレーザ照射光も照射して基準発光強度画像（Ｉｒｅｆ）を撮影した。その後、風洞を始動させ、通風画像（Ｉ）を撮影した。ダーク画像を基準発光強度画像（Ｉｒｅｆ）と通風画像（Ｉ）から減じた後、基準発光強度画像（Ｉｒｅｆ）と通風画像（Ｉ）の強度比（Ｉｒｅｆ／Ｉ）を求めた。この強度比から圧力を算出した。 In the measurement, first, a dark image and a reference emission intensity image (I ref ) were taken under atmospheric pressure. Since the laser light used in the particle image flow velocity measurement enters the absorption band of the pressure-sensitive paint, when taking a reference emission intensity image, in addition to the excitation light for pressure-sensitive paint measurement, a sheet image for particle image flow velocity measurement A reference emission intensity image (I ref ) was taken by irradiating the laser irradiation light. Then, the wind tunnel was started and the ventilation image (I) was image | photographed. After subtracting the dark image from the reference emission intensity image (I ref) and ventilation image (I), the reference luminous intensity image (I ref) and the intensity ratio of the draft image (I) and (I ref / I) was obtained. The pressure was calculated from this intensity ratio.
＜粒子画像流速測定データ処理方法＞
粒子画像流速測定では、図７のような粒子の散乱光画像を取得した。トレーサ粒子を流さず、シート状のレーザ照射光のみを照射した状態で測定部を撮影した画像を背景画像とした。粒子の散乱光画像から、この背景画像を減じたものを対象に処理を行った。１時刻目の画像から６４ｐｉｘｅｌ×６４ｐｉｘｅｌの領域を切り出し、２時刻目の同領域の画像と相関法によりパターンマッチングを行った。最も相関値が高くなる移動量を粒子の移動距離とした。この移動距離を１時刻目と２時刻目のレーザ照射の時間間隔で割ることにより、粒子の移動速度を算出した。
<Particle image velocimetry data processing method>
In the particle image flow velocity measurement, a scattered light image of particles as shown in FIG. 7 was acquired. An image obtained by photographing the measurement part in a state where only the sheet-like laser irradiation light was irradiated without flowing the tracer particles was used as a background image. Processing was performed on the image obtained by subtracting the background image from the scattered light image of the particles. An area of 64 pixels × 64 pixels was cut out from the image at the first time, and pattern matching was performed using the correlation method with the image of the same area at the second time. The amount of movement with the highest correlation value was taken as the distance of particle movement. The moving speed of the particles was calculated by dividing this moving distance by the time interval of laser irradiation at the first time and the second time.
＜結果＞
図８に、感圧塗料測定系と粒子画像流速測定系の複合システムによって測定した圧力場と速度場を時刻順に図８（ａ）から図８（ｄ）に示す。上段の分布図は圧力場を表し、下段のベクトル図は速度場を表す。測定開始時刻を０ｓとして、圧力場と速度場の測定時刻を図の左上に示す。気流は左から右に流れている。圧力分布は、実際はカラー画像であり、色が赤に近い（右よりの濃度の色）ほど圧力が高く、青に近い（左よりの濃度の色）ほど圧力が低いことを示す。時間の経過と共に、下流側から圧力が上昇していることが分かる。また、圧力変化の切り替わりは明瞭であり、衝撃波によって圧力が変化していることがうかがわれる。
下段の速度ベクトル図は、実際はカラー画像であり、色が赤に近いほど高速であることを表し、青に近いほど低速であることを示す（図８（ａ）の中心付近の濃い色が赤、図８（ｄ）の上下端付近の濃い色が青である。）。Ｔ＝１．００００ｓにおいては、ほぼ全領域において、ベクトルの色は赤であり、超音速気流であることが分かる。同時刻の圧力分布では、同位置においても、圧力上昇を見られる。
速度ベクトルのデータから、壁面において圧力上昇があっても、ダクト中央部は高速気流が流れており、衝撃波はダクト中央部の速度場測定領域には達していないことが分かる。Ｔ＝１．５６５ｓに達すると、速度ベクトル図においても、図中右側の下流に衝撃波が存在し、衝撃波と干渉した壁面近傍の境界層がはがれ、低速領域が存在していることが分かる。さらに時刻が進むと、図８（ｃ）や図８（ｄ）のように、ベクトルの色は緑色（中心付近の明るい色）に切り替わり、気流速度は圧力とは反対に低下することが分かる。
<Result>
FIG. 8 shows a pressure field and a velocity field measured by a combined system of a pressure-sensitive paint measurement system and a particle image flow velocity measurement system in order of time from FIG. 8 (a) to FIG. 8 (d). The upper distribution diagram represents the pressure field, and the lower vector diagram represents the velocity field. The measurement start time is 0 s, and the measurement times of the pressure field and velocity field are shown in the upper left of the figure. The airflow is flowing from left to right. The pressure distribution is actually a color image, and indicates that the pressure is higher as the color is closer to red (color with density from the right), and the pressure is lower as it is closer to blue (color with density from the left). It can be seen that the pressure increases from the downstream side as time passes. Moreover, the change of the pressure change is clear and it can be seen that the pressure is changed by the shock wave.
The lower speed vector diagram is actually a color image, and the closer the color is to red, the faster the speed is, and the closer the color is to blue, the slower the speed is (the dark color near the center in FIG. 8A is red). The dark color near the upper and lower ends of FIG. 8D is blue.) It can be seen that at T = 1.0000 s, the color of the vector is red in almost the entire region, indicating a supersonic airflow. In the pressure distribution at the same time, a pressure increase can be seen even at the same position.
From the velocity vector data, it can be seen that even if there is an increase in pressure on the wall surface, a high-speed airflow flows in the center of the duct, and the shock wave does not reach the velocity field measurement region in the center of the duct. When T = 1.565 s, it can be seen that in the velocity vector diagram, a shock wave exists on the downstream side on the right side of the drawing, the boundary layer in the vicinity of the wall surface that interferes with the shock wave peels off, and a low speed region exists. When the time further advances, as shown in FIGS. 8C and 8D, the color of the vector is switched to green (bright color near the center), and it can be seen that the air flow velocity is decreased opposite to the pressure.
感圧塗料測定の応答特性が、ドライアイス粒子によって失われていないことを示すために、図９に非定常圧力センサ（Ｋｕｌｉｔｅ社製）と感圧塗料測定の圧力分布の比較を示す。図９において縦軸は、大気圧で無次元化した壁面圧力を表し、横軸は、測定時刻を表す。濃い線（上方側で遷移する）は非定常圧力センサの測定結果であり、薄い線（下方側で遷移する）は感圧塗料測定の結果である。一部拡大した下段の図に示すように、両者の変動の形は良く一致しており、バイアス誤差を一定量含むものの、非定常感圧塗料測定の応答特性がドライアイス粒子によって失われていないことが分かる。 In order to show that the response characteristic of the pressure sensitive paint measurement is not lost by the dry ice particles, FIG. 9 shows a comparison of the pressure distribution of the unsteady pressure sensor (manufactured by Kulite) and the pressure sensitive paint measurement. In FIG. 9, the vertical axis represents the wall pressure made dimensionless at atmospheric pressure, and the horizontal axis represents the measurement time. The dark line (transition on the upper side) is the measurement result of the unsteady pressure sensor, and the thin line (transition on the lower side) is the result of the pressure-sensitive paint measurement. As shown in the lower part of the enlarged figure, the two fluctuations are in good agreement and contain a certain amount of bias error, but the response characteristics of unsteady pressure-sensitive paint measurement are not lost by dry ice particles. I understand that.
本発明に係る流体測定方法および流体測定装置は、航空宇宙分野をはじめとし、鉄道、自動車などの輸送機械、空調機、ファン、風車などの流体機械、エンジン、医療分野および化学プラント等で使用される管内流れなどの広い分野にわたり、非定常圧力場と非定常速度場の相関する振動や騒音、金属疲労などの問題を生じさせる流れ場の測定に対して利用可能である。
これらの分野において、非定常圧力場を生じさせる非定常流れの空間情報を速度場から取得することは、その原因となるメカニズム、形状を特定することを容易にする。結果として、これらの分野における機械の設計や効率の改善、騒音や振動の低減など多様な目的で用いることができる基本的な技術である。
The fluid measuring method and the fluid measuring device according to the present invention are used in aerospace field, transportation machines such as railways and automobiles, fluid machines such as air conditioners, fans and windmills, engines, medical fields and chemical plants. It can be used for measurement of flow fields that cause problems such as vibration, noise, and metal fatigue that correlate unsteady pressure field and unsteady velocity field over a wide range of fields such as pipe flow.
In these fields, obtaining the spatial information of the unsteady flow that generates the unsteady pressure field from the velocity field makes it easy to identify the mechanism and shape that cause the unsteady flow. As a result, it is a basic technology that can be used for various purposes such as machine design and efficiency improvement in these fields, noise and vibration reduction.
１００ ・・・ 流体測定装置
１０１ ・・・ 矩形ダクト
１０２ ・・・ 吸引手段
１０３ ・・・ バルブ
１０４ ・・・ 気流形成ノズル
１０５ ・・・ 気体供給手段
１０６ ・・・ 粒子供給タンク
１０７ ・・・ 粒子散布ノズル
１０８ ・・・ 粒子供給容器
１１１ ・・・ 感圧塗料
１１２ ・・・ 高速度カメラ
１１３ ・・・ 励起光源
１１４ ・・・ 光学フィルタ
１２１ ・・・ 可視化光源
１２２ ・・・ 高速度カメラ
１２３ ・・・ 光学フィルタ
１３１ ・・・ 昇華性粒子
１３２ ・・・ 噴射器
１３３ ・・・ 金属管
１３４ ・・・ 微小孔
１３５ ・・・ 側孔
DESCRIPTION OF SYMBOLS 100 ... Fluid measuring apparatus 101 ... Rectangular duct 102 ... Suction means 103 ... Valve 104 ... Airflow formation nozzle 105 ... Gas supply means 106 ... Particle supply tank 107 ... Particle Spray nozzle 108 ・ ・ ・ Particle supply container 111 ・ ・ ・ Pressure sensitive paint 112 ・ ・ ・ High speed camera 113 ・ ・ ・ Excitation light source 114 ・ ・ ・ Optical filter 121 ・ ・ ・ Visualization light source 122 ・ ・ ・ High speed camera 123 .... Optical filter 131 ... Sublimable particle 132 ... Injector 133 ... Metal tube 134 ... Micro hole 135 ... Side hole
Claims (6)
流体に接する物体表面の圧力分布を感圧塗料によって光学的に測定する圧力場測定工程と、流体内に可視性の粒子を散布して流体の空間挙動を光学的に測定する速度場測定工程とを有し、
前記感圧塗料を流体の圧力に応じた酸素濃度の変化で発光強度が変化するものとし、前記可視性の粒子を昇華性粒子とし、
前記圧力場測定工程および速度場測定工程を同時に行い、同一事象に対する圧力場と速度場の情報を時間方向で相関した情報として取得することを特徴とする流体測定方法。 A fluid measurement method for measuring a dynamic property of a fluid, comprising:
A pressure field measuring step for optically measuring the pressure distribution on the surface of the object in contact with the fluid with a pressure sensitive paint, and a velocity field measuring step for optically measuring the spatial behavior of the fluid by dispersing visible particles in the fluid; Have
The pressure-sensitive paint has a light emission intensity that changes due to a change in oxygen concentration according to the pressure of the fluid, and the visible particles are sublimable particles.
A fluid measurement method, wherein the pressure field measurement step and the velocity field measurement step are performed simultaneously, and information on the pressure field and the velocity field for the same event is acquired as information correlated in the time direction.
流体に接する物体表面に設けられ、流体の圧力に応じた酸素濃度の変化で発光強度が変化する感圧塗料と、
流体内に可視性の昇華性粒子を散布する粒子散布手段と、
前記感圧塗料に励起用の光を投射する励起光源と、
前記感圧塗料の発光を測定する圧力場測定手段と、
前記昇華性粒子を可視化するための光を投射する可視化光源と、
前記昇華性粒子からの散乱光または発光を測定する速度場測定手段と、
前記圧力場測定手段および速度場測定手段の同一事象に対する測定情報を時間方向で相関した情報として取得する情報取得手段とを有することを特徴とする流体測定装置。 A fluid measuring device for measuring dynamic characteristics of a fluid,
A pressure-sensitive paint that is provided on the surface of an object in contact with the fluid, and whose emission intensity changes with a change in oxygen concentration according to the pressure of the fluid;
A particle spraying means for spraying visible sublimable particles in the fluid;
An excitation light source that projects excitation light onto the pressure-sensitive paint;
Pressure field measuring means for measuring light emission of the pressure sensitive paint;
A visualizing light source for projecting light for visualizing the sublimable particles;
Velocity field measuring means for measuring scattered light or luminescence from the sublimable particles;
A fluid measurement apparatus comprising: information acquisition means for acquiring measurement information for the same event of the pressure field measurement means and the velocity field measurement means as information correlated in the time direction.
前記速度場測定手段および圧力場測定手段が、それぞれ観察すべき光以外を低減する光学フィルタを備えていることを特徴とする請求項５に記載の流体測定装置。 The pressure field measuring means is not directly received by the projection light of the visualization light source, and the velocity field measurement means is disposed so as not to directly receive the projection light of the excitation light source,
6. The fluid measuring device according to claim 5, wherein each of the velocity field measuring unit and the pressure field measuring unit includes an optical filter that reduces light other than light to be observed.
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