JP2008249528A - Technique for correcting temperature dependency of pressure-sensitive coating measuring method by time-serial temperature change - Google Patents
Technique for correcting temperature dependency of pressure-sensitive coating measuring method by time-serial temperature change Download PDFInfo
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- 238000000034 method Methods 0.000 title claims abstract description 59
- 239000011248 coating agent Substances 0.000 title abstract description 4
- 238000000576 coating method Methods 0.000 title abstract description 4
- 238000003384 imaging method Methods 0.000 claims abstract description 4
- 239000003973 paint Substances 0.000 claims description 52
- 238000012937 correction Methods 0.000 claims description 21
- 238000000691 measurement method Methods 0.000 claims description 12
- 238000011065 in-situ storage Methods 0.000 claims description 10
- 238000012360 testing method Methods 0.000 claims description 7
- 238000005286 illumination Methods 0.000 claims description 6
- 238000003705 background correction Methods 0.000 claims description 5
- 238000001914 filtration Methods 0.000 claims description 4
- 238000013507 mapping Methods 0.000 claims description 4
- 238000003702 image correction Methods 0.000 claims description 2
- 238000009423 ventilation Methods 0.000 abstract description 31
- 238000005259 measurement Methods 0.000 description 26
- 238000007796 conventional method Methods 0.000 description 10
- 230000001419 dependent effect Effects 0.000 description 5
- 238000002474 experimental method Methods 0.000 description 5
- 238000004020 luminiscence type Methods 0.000 description 4
- 238000009530 blood pressure measurement Methods 0.000 description 3
- 238000009529 body temperature measurement Methods 0.000 description 3
- 238000010586 diagram Methods 0.000 description 3
- 230000005284 excitation Effects 0.000 description 3
- 238000012935 Averaging Methods 0.000 description 2
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 2
- 238000011161 development Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 229910052760 oxygen Inorganic materials 0.000 description 2
- 239000001301 oxygen Substances 0.000 description 2
- 238000003672 processing method Methods 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 1
- 238000012625 in-situ measurement Methods 0.000 description 1
- 230000001678 irradiating effect Effects 0.000 description 1
- 239000005101 luminescent paint Substances 0.000 description 1
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- 238000012545 processing Methods 0.000 description 1
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- Measuring Fluid Pressure (AREA)
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Abstract
Description
本発明は航空宇宙機、自動車、鉄道、産業機械等の分野における表面圧力計測技術に関する。 The present invention relates to a surface pressure measurement technique in the fields of aerospace machines, automobiles, railways, industrial machines and the like.
まず、本発明の基礎となる感圧塗料(Pressure-Sensitive Paint;PSP)の発光強度と圧力の関係について説明する。感圧塗料計測は被計測物体のグローバルな表面圧力を計測することができる特徴を持っており、航空宇宙機や自動車開発における風洞実験において有効な計測手法であるが、同時に圧力だけでなく温度の影響を受けやすいという短所を併せ持つ。感圧塗料の計測原理は蛍光や燐光を発生する化学物質の中で、酸素濃度に感応して発光強度が著しく変化する物質の特性を利用したものである。感圧塗料発光強度I(p,T)と、圧力pおよび温度Tとの関係は式(1)のStern-Volmer の関係式で表される(非特許文献1参照)。なお、I0は酸素濃度がゼロの場合の発光強度を示す。
I0(T)/I(p,T)=1+K(T)・p ‥‥ (1)
ここで、I0を正確に計測することは困難であるため、一般には既知圧力prefの発光強度Iref (=I(pref,T))を得ることにより(1)式を正規化する。
Iref/I=A(T)+B(T)・p/pref ‥‥ (2)
式(1)と式(2)が示すように、感圧塗料の温度依存性は圧力計測精度に大きな影響を与える。
First, the relationship between the light emission intensity and pressure of a pressure-sensitive paint (PSP) which is the basis of the present invention will be described. Pressure-sensitive paint measurement has the feature that it can measure the global surface pressure of the object to be measured, and is an effective measurement method in wind tunnel experiments in aerospace aircraft and automobile development. It also has the disadvantage of being easily affected. The measurement principle of pressure-sensitive paints is based on the characteristics of chemical substances that generate fluorescence and phosphorescence and whose emission intensity changes significantly in response to oxygen concentration. The relationship between the pressure-sensitive paint emission intensity I (p, T), the pressure p, and the temperature T is expressed by the Stern-Volmer relational expression (1) (see Non-Patent Document 1). Note that I 0 represents the emission intensity when the oxygen concentration is zero.
I 0 (T) / I (p, T) = 1 + K (T) · p (1)
Here, since it is difficult to accurately measure I 0 , the expression (1) is normalized by generally obtaining the emission intensity I ref (= I (p ref , T)) of the known pressure p ref. .
I ref / I = A (T) + B (T) · p / p ref (2)
As shown in equations (1) and (2), the temperature dependence of the pressure-sensitive paint greatly affects the pressure measurement accuracy.
図8Aはpref=100kPa,T0=20℃の発光強度を基準Irefとした場合の、発光強度比Iref(pref,T0)/I(p,T)と、圧力比p/prefの関係を示したグラフである。この場合T=20℃以外では、IrefとIにおける温度が異なるものとなっている。このグラフでは、同じ圧力でも温度により感圧塗料発光強度が変化していることが示されており、感圧塗料が温度にも感度を持つことが改めて確認できる。
図8Bは既知圧力prefの発光強度Irefと、任意圧力pの感圧塗料発光強度Iで温度を同一にした場合の、発光強度比Iref (pref,T)/I(p,T)と、圧力比p/prefの関係を示したグラフである。このグラフは、T=10℃・100kPaの発光強度をIrefとしてT=10℃での任意圧力による発光強度を正規化し、同様に、T=20℃・100kPaの発光強度をIrefとしてT=20℃での任意圧力による発光強度を正規化するというようにして整理したものである。つまり、IrefとIにおける温度は同一である。この場合、圧力比に対する発光強度比の縦軸における広がりは1本の較正特性線で近似できる程度に狭くなることが分かる。
FIG. 8A shows a light emission intensity ratio I ref (p ref , T 0 ) / I (p, T) and a pressure ratio p / T where the light emission intensity at p ref = 100 kPa and T 0 = 20 ° C. is the reference I ref. It is the graph which showed the relationship of pref . In this case, except at T = 20 ° C., the temperatures at I ref and I are different. This graph shows that the pressure-sensitive paint emission intensity changes with temperature even at the same pressure, and it can be confirmed again that the pressure-sensitive paint has sensitivity to temperature.
FIG. 8B shows the emission intensity ratio I ref (p ref , T) / I (p, T when the temperature is the same at the emission intensity I ref at a known pressure p ref and the pressure-sensitive paint emission intensity I at an arbitrary pressure p. ) And the pressure ratio p / p ref . This graph normalizes the emission intensity at an arbitrary pressure at T = 10 ° C. with the emission intensity at T = 10 ° C./100 kPa as I ref , and similarly, the emission intensity at T = 20 ° C./100 kPa as I ref T = The light emission intensity at an arbitrary pressure at 20 ° C. is normalized and arranged. That is, the temperature at I ref and I is the same. In this case, it can be seen that the spread in the vertical axis of the emission intensity ratio with respect to the pressure ratio becomes narrow enough to be approximated by one calibration characteristic line.
感圧塗料発光強度データを圧力データヘ変換する方法にin-situ法がある。in-situ法は、図7に示すように、圧力変換器に接続した圧力孔で得た圧力データと圧力孔まわりの感圧塗料発光強度比を関連づけて式(2)から最小二乗法により係数A,Bを求め、較正特性線を得る方法である。したがって、模型まわりの圧力分布は、得られたin-situ較正特性線に基づいて模型まわりの感圧塗料塗装部の発光強度比から得ることができる。 There is an in-situ method for converting pressure-sensitive paint emission intensity data into pressure data. As shown in FIG. 7, the in-situ method relates the pressure data obtained at the pressure holes connected to the pressure transducer to the pressure-sensitive paint emission intensity ratio around the pressure holes, and calculates the coefficient using the least square method from equation (2). In this method, A and B are obtained to obtain a calibration characteristic line. Therefore, the pressure distribution around the model can be obtained from the emission intensity ratio of the pressure-sensitive paint coating portion around the model based on the obtained in-situ calibration characteristic line.
一般的に、基準発光強度Irefは風洞通風前の模型温度が均一な無風時に取得される。しかし、風洞実験のように、通風中模型に不均一な温度分布が生じる場合には図8Aで示した様に、感圧塗料の温度依存性による計測誤差が無視できない。模型の温度を計測した上で感圧塗料の温度依存性を補正するという方法もあるが、温度計測が実用上困難な場合には適用できない。そこで、図8Bに示した感圧塗料の特性を活かし、風洞実験において、通風時と同一温度で既知圧力における基準発光強度をIrefとして得ることを考える。風洞実験では通風時の模型温度を均一にすることは難しいため、基準の模型温度分布を通風時の温度分布と一致させる。実用上、模型温度が通風時の温度分布と最も近く、かつ、既知圧力分布を得られるのは風洞の通風停止直後の無風時であると考えられ、通風停止直後の無風時の発光強度をIrefとして採用した例が報告されている(非特許文献2参照)。 In general, the reference emission intensity I ref is acquired when there is no wind in which the model temperature before the wind tunnel ventilation is uniform. However, when a non-uniform temperature distribution occurs in the model during ventilation as in the wind tunnel experiment, as shown in FIG. 8A, the measurement error due to the temperature dependence of the pressure-sensitive paint cannot be ignored. There is also a method of correcting the temperature dependence of the pressure sensitive paint after measuring the temperature of the model, but it is not applicable when temperature measurement is practically difficult. Therefore, taking advantage of the characteristics of the pressure-sensitive paint shown in FIG. 8B, in a wind tunnel experiment, it is considered to obtain a reference emission intensity at a known pressure at the same temperature as that during ventilation as I ref . In the wind tunnel experiment, it is difficult to make the model temperature uniform during ventilation, so the standard model temperature distribution is matched with the temperature distribution during ventilation. Practically, the model temperature is closest to the temperature distribution at the time of ventilation, and the known pressure distribution can be obtained when there is no wind immediately after the ventilation stop of the wind tunnel. An example adopted as ref has been reported (see Non-Patent Document 2).
従来手法の一例を図6Aのフローチャートに沿って説明する。まず、CCDカメラで取得した複数の画像データに対し、平均化・ダーク減算(熱雑音成分の除去)・フラットフィールド補正(画像周辺部の光量不足の補正)・フィルタリング(画像ノイズ等を軽減)等を行い感圧塗料発光強度画像データを得る。次に、発光強度画像データを模型表面形状の三次元格子ヘマッピングする。その後、翼の付け根部と胴体の翼基部など近接した部位からの光の干渉を補正するself-illumination補正を行う。その後圧力孔まわりの発光強度データと圧力孔を介して計測した圧力データとの関係づけを行うin-situ較正法を施して最後に模型全体の圧力値を得るというものである。図6Bはこの手法を模式的に示したものである。
ところが、感圧塗料の温度依存性による計測誤差を軽減させるため、通風停止直後の無風時の発光強度を基準Irefとする上記の従来方法を実施した場合、次の問題が発生する。感圧塗料計測で利用する感圧塗料の発光強度は微弱であり、計測精度を確保するためにCCDカメラのショットノイズを数十枚の画像を平均化することで軽減させている。しかし、その画像取得に要する時間において、模型温度が変化し、発光強度も徐々に変化してしまう。そのため、ショットノイズ軽減を目的に平均化した発光強度データは、同時に、時間とともに変化した発光強度の平均値となり、誤差を増やす結果となる。 However, in order to reduce the measurement error due to the temperature dependence of the pressure-sensitive paint, the following problem occurs when the above-described conventional method in which the emission intensity during no wind immediately after the stop of ventilation is used as the reference I ref is implemented. The light emission intensity of the pressure-sensitive paint used for pressure-sensitive paint measurement is weak, and the shot noise of the CCD camera is reduced by averaging several tens of images to ensure measurement accuracy. However, in the time required for the image acquisition, the model temperature changes and the light emission intensity gradually changes. For this reason, the emission intensity data averaged for the purpose of reducing shot noise simultaneously becomes an average value of the emission intensity that has changed with time, resulting in increased errors.
ここで、模型上の代表位置1点における通風時と通風停止直後(無風時)の感圧塗料発光強度の変化を計測した結果を図1に示す。図1より、撮像中に変化する模型温度により発光強度が時々刻々と変化している様子が分かる。図1Aのデータは通風停止直前の約9分間に64枚の画像を撮像したものであり、図1Bのデータは通風停止直後の約8分間に64枚の画像を撮像したものである。ここで、図中の破線はCCDカメラのショットノイズ軽減を目的として行った平均値である。特に、平均値と通風停止直後の基準発光強度の値(図1Bの矢印近傍)には大きな差が生じていることが分かる。
本発明の課題は、時間をかけて取得した複数枚の画像データの平均値と通風停止直後の基準発光強度の値に大きな差が生じていることに起因する誤差を少なくし、より精度の良い感圧塗料計測法の温度依存性補正手法を提示することにある。
Here, FIG. 1 shows the result of measuring the change in the light emission intensity of the pressure-sensitive paint at one representative position on the model at the time of ventilation and immediately after the ventilation was stopped (no wind). From FIG. 1, it can be seen that the light emission intensity changes from moment to moment due to the model temperature that changes during imaging. The data in FIG. 1A is obtained by capturing 64 images in about 9 minutes immediately before the ventilation stop, and the data in FIG. 1B is obtained by capturing 64 images in about 8 minutes immediately after the suspension of ventilation. Here, the broken line in the figure is an average value for the purpose of reducing shot noise of the CCD camera. In particular, it can be seen that there is a large difference between the average value and the value of the reference emission intensity immediately after the ventilation stop (in the vicinity of the arrow in FIG. 1B).
An object of the present invention is to reduce errors caused by a large difference between the average value of a plurality of pieces of image data acquired over time and the value of the reference light emission intensity immediately after the stop of ventilation, thereby improving accuracy. The purpose is to present a method for correcting the temperature dependence of the pressure sensitive paint measurement method.
本発明における感圧塗料計測法での時系列的温度変化による温度依存性補正手法は、表面に感圧塗料が塗られた試験体において、まず、温度分布と圧力分布が存在する環境下で発光強度(画像)データを得るステップを踏み、次に、前記環境下と同一温度分布だが均一圧力下での発光強度(画像)データを得るステップを踏む。その後、各発光強度データから試験体における発光強度の時系列変化を曲線近似するステップを踏み、それらの近似曲線から、均一圧力環境に切り替える直前の発光強度データと切り替えた直後の発光強度データとを求めるステップを踏む。
また、圧力分布が存在する環境下と均一圧力環境に切替えた直後に撮像した複数枚の各画像データを試験体表面の三次元格子にマッピングするステップと、マッピングされた各点における発光強度の時系列変化を曲線近似するステップと、該時系列変化の近似曲線から均一圧力環境に切替え直前の発光強度データと切替え直後の発光強度データとを採用して各点の発光強度比を得るステップを踏むようにした。
本発明の感圧塗料計測法の時系列的温度変化による温度依存性補正手法における1形態では、近似曲線から得た発光強度データを試験体の圧力孔を介して計測した圧力値に基づいてin-situ較正するステップを踏むようにした。
また、本発明の感圧塗料計測法の時系列的温度変化による温度依存性補正手法における異なる1形態では、撮像した各画像データにはダーク減算、フラットフィールド補正、フィルタリングを施して画像補正を行うステップを踏むようにした。
本発明の感圧塗料計測法の時系列的温度変化による温度依存性補正手法における更なる1形態では、発光強度データに対し試験体の三次元構造から光の干渉が生じる領域に self-illumination 補正を施すステップを踏むようにした。
In the pressure-sensitive paint measurement method according to the present invention, the temperature dependence correction method based on the time-series temperature change is first performed in a test body having a pressure-sensitive paint applied to the surface, and light emission is performed in an environment where temperature distribution and pressure distribution exist. Steps for obtaining intensity (image) data are taken, and then steps for obtaining light emission intensity (image) data under the same temperature distribution as the environment but under a uniform pressure are taken. After that, the step of approximating the time-series change of the emission intensity in the specimen from each emission intensity data is taken, and the emission intensity data immediately before switching to the uniform pressure environment and the emission intensity data immediately after switching are calculated from these approximate curves. Take the steps you want.
In addition, a step of mapping a plurality of pieces of image data taken immediately after switching to an environment where pressure distribution exists and a uniform pressure environment onto a three-dimensional grid on the surface of the test object, and at the time of emission intensity at each mapped point The steps of approximating the series change to a curve and the steps of obtaining the emission intensity ratio at each point by adopting the emission intensity data immediately before switching to the uniform pressure environment and the emission intensity data immediately after switching from the approximate curve of time series change to the uniform pressure environment. I tried to do it.
In one form of the temperature dependence correction method by the time-series temperature change of the pressure-sensitive paint measurement method of the present invention, the emission intensity data obtained from the approximate curve is based on the pressure value measured through the pressure hole of the specimen. -Situ calibration steps are now taken.
In another embodiment of the pressure-dependent paint measuring method according to the present invention in the temperature-dependent correction method based on the time-series temperature change, each imaged image data is subjected to dark subtraction, flat field correction, and filtering to perform image correction. I took steps.
In a further embodiment of the temperature-dependent correction method based on the time-series temperature change of the pressure-sensitive paint measurement method of the present invention, self-illumination correction is performed in a region where light interference occurs from the three-dimensional structure of the specimen with respect to the emission intensity data. I took steps to apply.
本発明の感圧塗料計測法の時系列的温度変化による温度依存性補正手法は、まず、圧力分布が存在する環境下で複数枚の画像(発光強度)データを得るステップを踏む。次に、均一圧力環境下へ切替えた直後に、複数枚の画像(発光強度)データを得るステップを踏む。さらに、発光強度データ各点における時系列変化を曲線近似するステップを踏む。それらの近似曲線から、均一圧力環境下へ切替える直前および切替えた直後の発光強度データを求める。
本発明は、画像を取得する間の模型温度変化による発光強度変化で生じる計測誤差を軽減できる。また、複数画像データによりCCDカメラのショットノイズを軽減できる。さらに、温度計測器を必要としないため計測システムを簡素化できる。
圧力分布が存在する環境下と、その後均一圧力環境に切替えた直後に撮像した複数枚の画像データの各発光強度データを試験体表面の三次元格子にマッピングするステップと、マッピングされた各点における発光強度の時系列変化を曲線近似するステップと、該時系列変化の近似曲線から、均一圧力環境に切替える直前の発光強度データと切替え直後の発光強度データとを採用して各点の発光強度比を得るステップを踏むようにした本発明は、試験体表面における精度の高い圧力分布を得ることができる。
In the temperature-dependent correction method based on time-series temperature changes in the pressure-sensitive paint measurement method of the present invention, first, a step of obtaining a plurality of image (emission intensity) data in an environment where a pressure distribution exists is taken. Next, immediately after switching to a uniform pressure environment, a step of obtaining a plurality of image (emission intensity) data is performed. Further, a step of approximating the time series change at each point of the emission intensity data with a curve is taken. From these approximate curves, emission intensity data immediately before and after switching to a uniform pressure environment are obtained.
The present invention can reduce measurement errors caused by changes in emission intensity due to changes in model temperature during image acquisition. Further, the shot noise of the CCD camera can be reduced by the plural image data. Furthermore, since a temperature measuring instrument is not required, the measuring system can be simplified.
Mapping each emission intensity data of a plurality of image data captured in an environment where pressure distribution exists and immediately after switching to a uniform pressure environment to a three-dimensional grid on the surface of the specimen, and at each mapped point A step of approximating the time-series change of the emission intensity with a curve, and using the approximation curve of the time-series change, the emission intensity data immediately before switching to the uniform pressure environment and the emission intensity data immediately after switching are used to calculate the emission intensity ratio at each point. According to the present invention in which the step of obtaining is taken, a highly accurate pressure distribution on the surface of the test body can be obtained.
本発明の感圧塗料計測法の時系列的温度変化による温度依存性補正手法における1形態では、圧力孔データに基づいたより精度の高い感圧塗料による圧力計測を実現できる。
また、撮像した各画像データにはダーク減算、フラットフィールド補正、フィルタリングを施して画像補正を行うものとした本発明の感圧塗料計測法の時系列的温度変化による温度依存性補正手法における異なる1形態では、カメラがもつ計測誤差成分を是正より精度の高い計測結果を得ることができる。
温度依存性を補正を施した発光強度データを試験体表面の三次元構造から干渉が予測される領域に self-illumination 補正を施すようにした本発明の感圧塗料計測法の時系列的温度変化による温度依存性補正手法における更なる1形態では、近接した部位からの光の干渉を補正し、より精度の高い計測結果を得ることができる。
In one form of the temperature dependency correction method using a time-series temperature change of the pressure-sensitive paint measurement method of the present invention, it is possible to realize pressure measurement with a pressure-sensitive paint with higher accuracy based on the pressure hole data.
Further, in the pressure-dependent paint measuring method according to the present invention in which dark image subtraction, flat field correction, and filtering are performed on each imaged image data, the temperature dependence correction method using a time-series temperature change is different. In the embodiment, it is possible to obtain a measurement result with higher accuracy than correcting the measurement error component of the camera.
Time-series temperature change of the pressure-sensitive paint measurement method of the present invention, in which self-illumination correction is applied to the region where interference is predicted from the three-dimensional structure of the specimen surface. In a further embodiment of the temperature dependency correction method according to, it is possible to correct the interference of light from a nearby part and obtain a more accurate measurement result.
本発明者らは、通風時と基準(通風停止直後の無風時)の模型温度の差を可能な限り少なくすることを考えた。そのため、図1の実線で示されるように、発光強度の変化に対する近似曲線を最小二乗法により定義する。つまり、通風時の発光強度データIには通風停止直前(図1Aの矢印)における近似曲線上での値を使用し、同様に、基準(通風停止直後:無風時)の発光強度データIrefには計測開始時刻(図1Bの矢印)における近似曲線上での値を使用する。近似曲線を適用することにより、時間的にランダムに発生するショットノイズの影響は軽減され、また、通風後の計測(CCDカメラ撮影)が可能な範囲において最も通風中の温度分布に近い無風時(基準)の発光強度データが得られると考えられる。なお、この発光強度の近似曲線定義および演算は、模型上の空間的な発光強度データ各点で個々に実施する。 The inventors of the present invention have considered to minimize the difference in model temperature between ventilation and reference (no wind immediately after stopping ventilation) as much as possible. Therefore, as shown by the solid line in FIG. 1, an approximate curve for the change in emission intensity is defined by the least square method. That is, the value on the approximate curve immediately before the stop of ventilation (arrow in FIG. 1A) is used for the emission intensity data I at the time of ventilation. Similarly, the emission intensity data I ref of the reference (immediately after the stop of ventilation: no wind) is used. Uses the value on the approximate curve at the measurement start time (arrow in FIG. 1B). By applying an approximate curve, the effects of shot noise that occurs randomly in time are reduced, and there is no wind (close to the temperature distribution during ventilation) in the range where measurement after ventilation (CCD camera shooting) is possible ( Standard) emission intensity data can be obtained. Note that the approximate curve definition and calculation of the emission intensity are individually performed at each point of the spatial emission intensity data on the model.
図4に示されるような感圧塗料を表面に塗装した模型1を風洞2内に設置すると共に、この模型1に対して励起用の光を照射する光源3とこの模型1を撮影するCCDカメラ4を風洞2の側部に配置した感圧塗料計測システムを用いて計測を行う。図2のAに示すように、ステップ1として光源3で励起光を照射した状態で、まず風洞通風時の画像データを複数枚取得する。続いて風洞内の通風を停止すると共に、その際の画像データ(基準)を複数枚取得する。ステップ2ではCCDカメラで取得した画像データ1枚を特定する。ステップ3で特定した1枚の画像に対してダーク減算・フラットフィールド補正等を行う。次に、ステップ4で発光強度画像データを模型表面の三次元格子ヘマッピングする。ステップ5でマッピングした発光強度データをメモリに格納する。ステップ6でこの画像が最後の画像かどうかを確認し、まだ未処理画像データがあるときはステップ2に戻り、次の画像データを特定してステップ3に進む。数十枚の画像を取得した場合は同数のマッピングされた発光強度データを得る。すべての画像についてマッピングした発光強度データをメモリに格納できたならば、ステップ7に進み、基準(無風)時および通風時ともに、発光強度データの時系列変化に対する近似曲線を最小二乗法により求める。ステップ8で、通風時の発光強度データIとしては計測最終時刻(通風停止直前)における近似曲線上での値を採用し、また、基準の発光強度データIrefとしては計測開始時刻(通風停止直後:無風時)における近似曲線上での値を採用する。この近似曲線を用いた処理は格子上の各点に対して実施する。 A model 1 having a pressure-sensitive paint coated on its surface as shown in FIG. 4 is installed in the wind tunnel 2, and a light source 3 for irradiating excitation light to the model 1 and a CCD camera for photographing the model 1 Measurement is performed using a pressure-sensitive paint measurement system in which 4 is arranged on the side of the wind tunnel 2. As shown in A of FIG. 2, in step 1, a plurality of image data when the wind tunnel is ventilated is acquired in a state where excitation light is emitted from the light source 3. Subsequently, the ventilation in the wind tunnel is stopped, and a plurality of image data (reference) at that time are acquired. In step 2, one piece of image data acquired by the CCD camera is specified. Dark subtraction, flat field correction, and the like are performed on one image specified in step 3. Next, in step 4, the emission intensity image data is mapped to the three-dimensional lattice on the model surface. The emission intensity data mapped in step 5 is stored in the memory. In step 6, it is confirmed whether or not this image is the last image. If there is still unprocessed image data, the process returns to step 2, the next image data is specified, and the process proceeds to step 3. When several tens of images are acquired, the same number of mapped emission intensity data is obtained. If the luminescence intensity data mapped for all the images can be stored in the memory, the process proceeds to step 7, and an approximate curve for the time series change of the luminescence intensity data is obtained by the least square method at both the reference (no wind) and the ventilation. In step 8, the value on the approximate curve at the final measurement time (immediately before the ventilation is stopped) is adopted as the emission intensity data I at the time of ventilation, and the measurement start time (immediately after the ventilation is stopped) is used as the reference emission intensity data Iref. : The value on the approximate curve at the time of no wind) is adopted. Processing using this approximate curve is performed for each point on the grid.
このようにして模型1における各点で、通風時と無風時での温度が最も近い発光強度データの比Iref/Iを格子各点について取得したなら、ステップ9で、従来手法と同様に、CCDカメラで撮像した二次元画像を三次元格子へマッピングする際には本来カメラに写らない部位の情報を削除する隠面消去を行い、ステップ10では、self-illumination補正を行う。このself-illumination補正は、例えば翼上の感圧塗料発光データには翼上で反射した胴体上での感圧塗料の発光成分が含まれることによって、本来よりも強い発光強度で計測されるために生じる誤差を補正するものである。ステップ11で、各部位発光強度データを圧力孔を介して計測した圧力値と関係づけるin-situ較正を施し、ステップ12で模型表面についての圧力値(圧力分布)を得るというものである。図2Bはこの手法を模式的に示したものである。 Thus, if the ratio I ref / I of the emission intensity data with the closest temperature at the time of ventilation and no wind at each point in the model 1 is obtained for each point of the grid, in step 9, as in the conventional method, When mapping a two-dimensional image captured by a CCD camera onto a three-dimensional lattice, hidden surface removal is performed to delete information on a portion that is not originally reflected in the camera. In step 10, self-illumination correction is performed. This self-illumination correction is, for example, because the pressure-sensitive paint emission data on the wing includes the light-emitting component of the pressure-sensitive paint on the fuselage reflected on the wing, so that it is measured with a stronger emission intensity than the original. This is to correct an error occurring in the above. In step 11, in-situ calibration is performed to relate each region emission intensity data to the pressure value measured through the pressure hole, and in step 12, the pressure value (pressure distribution) on the model surface is obtained. FIG. 2B schematically shows this method.
航空機の模型を用い、従来の方法(図6)で処理した場合と本発明の方法(図2)で処理した場合のデータを図3に示す。本実験は宇宙航空研究開発機構6.5m×5.5m低速風洞において航空機の半裁模型(図4の模型がこれに相当)を使用して実施したものである。模型迎角は5degであり、主流の風速は60m/sである。一般に、IRカメラによる温度計測では風洞の観測窓の材質に制限が生じる。また、半裁模型を使用した場合は、片舷側に温度計測用の感温塗料を塗装する方法(特許文献1)は適用できない。そのため、本発明の手法が必要となる。なお、通風中の風速や模型姿勢角条件は一定であり、また、模型姿勢条件を変えずに通風を停止した。 FIG. 3 shows data when an aircraft model is used and processed by the conventional method (FIG. 6) and when processed by the method of the present invention (FIG. 2). This experiment was conducted using an aircraft half model (the model in Fig. 4 corresponds to this) in the 6.5m x 5.5m low speed wind tunnel of the Japan Aerospace Exploration Agency. The model attack angle is 5deg, and the mainstream wind speed is 60m / s. In general, temperature measurement using an IR camera places restrictions on the material of the observation window of the wind tunnel. Moreover, when a half-cut model is used, the method of applying a temperature-sensitive paint for temperature measurement on one side (Patent Document 1) cannot be applied. Therefore, the method of the present invention is required. Note that the wind speed and model attitude angle conditions during ventilation were constant, and ventilation was stopped without changing the model attitude conditions.
図3Bと図3Cに in-situ法による較正特性線を示す。この較正特性線は、図5にて線で示す翼上面の3断面に設けた圧力孔から得た圧力データと対応する圧力孔周りの発光強度データとの関係を個々にグラフにプロットし、最小二乗法により線形近似を行ったものである。得られた較正特性線を使用して算出した翼上面の圧力係数(Cp)分布を図5に示し、また、図5の3断面の内、矢印で示す断面の母翼上面での圧力係数分布を図3Aに示す。以下に、従来手法と本手法での結果を比較する。まず、図3B,Cの較正特性線にて従来手法(図3B)ではデータに大きなバラつきが見られるのに対し、本手法(図3C)ではデータのバラつきが抑えられていることが分かる。ここで重要なことは、in-situ法では得られた較正特性線を使用して図5の様に模型全体の発光強度データを圧力(圧力係数)データへ変換するため、較正でのデータのバラつきは、感圧塗料計測の計測誤差に直結することである。ちなみに、図3B,Cのプロットされたデータと求めた較正特性線での圧力係数における差をRMS(Root Mean Square;二乗平均平方根)で表すと、従来方法の場合、約0.25であるのに対し、本手法の場合は約0.13であり、本手法の方が計測誤差を軽減できることが分かる。次に、図3Aの母翼上の圧力係数分布を見ると、点線で示す従来手法では感圧塗料(PSP)計測値と丸印で示す圧力孔計測値との間に大きな差が見られるのに対し、実線で示す本手法では感圧塗料計測値と圧力孔計測値との差が抑えられていることが分かる。以上のことから、本手法が有効であることが確認できる。 FIG. 3B and FIG. 3C show calibration characteristic lines by the in-situ method. The calibration characteristic line is a graph in which the relationship between the pressure data obtained from the pressure holes provided in the three cross sections on the blade upper surface indicated by the line in FIG. 5 and the emission intensity data around the corresponding pressure holes is plotted in a graph. The linear approximation is performed by the square method. FIG. 5 shows the pressure coefficient (Cp) distribution on the blade upper surface calculated using the calibration characteristic line obtained, and the pressure coefficient distribution on the upper surface of the main blade of the cross section indicated by the arrow among the three cross sections in FIG. Is shown in FIG. 3A. The results of the conventional method and this method are compared below. First, it can be seen from the calibration characteristic lines in FIGS. 3B and 3C that the conventional method (FIG. 3B) shows a large variation in data, whereas the present method (FIG. 3C) suppresses the variation in data. The important point here is that the in-situ method uses the calibration characteristic line obtained to convert the emission intensity data of the entire model into pressure (pressure coefficient) data as shown in FIG. The variation is directly related to the measurement error of pressure-sensitive paint measurement. Incidentally, the difference in pressure coefficient between the plotted data of FIGS. 3B and 3C and the obtained calibration characteristic line is expressed by RMS (Root Mean Square), which is about 0.25 in the conventional method. In the case of this method, it is about 0.13, and it can be seen that this method can reduce the measurement error. Next, looking at the pressure coefficient distribution on the main wing in FIG. 3A, there is a large difference between the pressure-sensitive paint (PSP) measurement value and the pressure hole measurement value indicated by a circle in the conventional method indicated by the dotted line. On the other hand, it can be seen that the difference between the pressure-sensitive paint measurement value and the pressure hole measurement value is suppressed in the present method indicated by the solid line. From the above, it can be confirmed that this method is effective.
本発明の感圧塗料計測法の時系列的温度変化による温度依存性補正手法は、航空宇宙機開発のみならず、鉄道、自動車等の車体や、産業機械における表面圧力場計測に広く応用することができる。 The temperature dependence correction method by time-series temperature change of the pressure-sensitive paint measurement method of the present invention is widely applied not only to aerospace vehicle development, but also to surface pressure field measurement in the body of railways, automobiles, etc. and industrial machinery. Can do.
1 模型(試験体) 2 風洞
3 励起光源 4 CCDカメラ
DESCRIPTION OF SYMBOLS 1 Model (test body) 2 Wind tunnel 3 Excitation light source 4 CCD camera
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JP2010243400A (en) * | 2009-04-08 | 2010-10-28 | Japan Aerospace Exploration Agency | Building berth support interference correcting method in subsonic half model wind tunnel test |
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