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ارزیابی روش PIV در تعیین مقیاس های آشفتگی | ||
| تحقیقات مهندسی صنایع غذایی | ||
| مقاله 7، دوره 9، شماره 4، اسفند 1387، صفحه 85-102 اصل مقاله (465.12 K) | ||
| نوع مقاله: مقاله پژوهشی | ||
| نویسندگان | ||
| محمد موحدان* 1؛ میشل بلورژه2 | ||
| 1عضو هیئت علمی مؤسسه تحقیقات فنی و مهندسی کشاورزی | ||
| 2استاد دانشگاه کان فرانسه | ||
| چکیده | ||
| با توجه به پیچیدگیها و کاربردهای فراوان آشفتگی جریان، شناخت صحیح و کمّی مقیاسهای این نوع جریان در مسائل مختلف اهمیت ویژهای دارد. بهمنظور تعیین مقیاسهای آشفتگی، از روشهای آزمایشگاهی متفاوت میتوان بهره جست. اما نکتة مهم در استفاده از این روشها، صحت و دقت آنهاست. در این مقاله ابتدا ضمن بررسی روش مرسوم تیلور جهت تعیین مقیاسهای آشفتگی، روش تعیین ضرایب همبستگی با استفاده از تکنیکهای آزمایشگاهی نظیر سرعت سنج سیم داغ، سرعتسنج لیزری بررسی میشود و پس از اجرای آزمایش روی یک جریان روباز، کارایی سیستم سرعتسنجی با تصویربرداری از ذرات در تعیین مقیاسهای آشفتگی بررسی خواهد شد. نتایج این تحقیق نشان میدهد که روش ضرایب همبستگی و بهخصوص استفاده از سیستم سرعتسنجی با تصویربرداری از ذرات، به رغم محدودیتهای آن در فرکانس تصویربرداری و تفکیک پذیری دوربین و پالسهای لیزر، میتواند دسترسی به مقیاسهای آشفتگی در شرایط پیچیده را هموار سازد. | ||
| عنوان مقاله [English] | ||
| Assessment of PIV Technique on Determination of Turbulence Scales | ||
| چکیده [English] | ||
| The proper and quantitative recognition of the scale of turbulence in regard to issues such as sediment transport is of major importance. Different experimental techniques can be used to determining the scale of turbulence, but the accuracy of these techniques is open to question. In this paper, after a review of the Taylor method, the restrictions and advantages of velocity measurement techniques such as hot wire anemometry (HWA), laser doppler velocimetry (LDV) and particle image velocimetry (PIV) are described. Correlation coefficients were applied to determine the scale of turbulence using these techniques. The results showed that the main restrictions of the HWA technique were its intrusiveness and the sensitivity of the sensor. The LDV technique was restricted to measuring correlation coefficients in small distances and for just one velocity component. The results showed that the PIV technique has restrictions in its framing rate, saving image, image resolution and laser pulsing frequencies. However, considering the large spatial domain of PIV and its non-intrusive measurements and especially the continuous development of its capabilities, PIV is an appropriate technique for determination of the scale of the flow of turbulence. | ||
| کلیدواژهها [English] | ||
| Correlation coefficient, Experimental Technique, Laser Doppler Velocimetry, Particle Image Velocimetry, Turbulence Scale | ||
| مراجع | ||
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