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بررسی نیمه تحلیلی نویز لبه فرار لایه مرزی آشفته با استفاده از اندازه گیری فشار ناپایای سطح | ||
| نشریه مهندسی مکانیک امیرکبیر | ||
| مقاله 6، دوره 51، شماره 6، بهمن و اسفند 1398، صفحه 1253-1270 اصل مقاله (1.27 M) | ||
| نوع مقاله: مقاله پژوهشی | ||
| شناسه دیجیتال (DOI): 10.22060/mej.2017.12480.5352 | ||
| نویسندگان | ||
| عباس افشاری1؛ علی اکبر دهقان* 2؛ محمد فرمانی3 | ||
| 1دانشجوی دکترا/ دانشگاه یزد | ||
| 2هیلت علمی-دانشگاه یزد | ||
| 3دانشجوی دکتری/ دانشگاه یزد | ||
| چکیده | ||
| نویز لبه فرار لایه مرزی آشفته یکی از منابع اصلی نویز آیرودینامیکی بوده و در دهه های گذشته مطالعات گستردهای روی آن انجام گرفته است. در مطالعه حاضر جهت اندازه‌گیری پارامترهای تعیین کننده نویز لبه فرار شامل طیف فشار سطح، طول مشخصه نوسانات فشار سطح در راستای دهانه بال و سرعت جابجایی ساختارهای گردابه ای در محدوده لبه فرار، از یک صفحه تخت مجهز به حسگرهای فشار سطحی در دو راستای جریان و دهانه بال استفاده شده است. طول مشخصه در راستای دهانه مدل و سرعت جابجایی ساختارهای گردابه-ای، به ترتیب از طریق داده‌برداری همزمان فشار ناپایای سطح در نقاط مختلف در راستای دهانه مدل و در راستای جریان محاسبه شده است. نتایج نشان می‌دهد که بهترین اجتماع داده‌های طیف فشار سطح در محدوده بسامدهای پایین و بسامدهای میانی و بالا به ترتیب به ازای استفاده از مقیاس-های الیه مرزی خارجی و داخلی حاصل خواهد شد. همچنین توابع همدوسی طولی و عرضی، به ترتیب اطلاعات مناسبی از طول عمر ساختارهای گردابه ای و ابعاد فیزیکی آنها ارائه می‌دهد. در نهایت، نویز لبه فرار دوردست ناشی از جریان عبوری از روی صفحه تخت با استفاده از مدل تحلیلی امیت-راجر پیش بینی شده که نتایج نشان دهنده کارایی مناسب این مدل در پیش‌بینی نویز لبه فرار لایه مرزی آشفته است. | ||
| کلیدواژه‌ها | ||
| نویز لبه فرار؛ لایه مرزی آشفته؛ طیف فشار سطح؛ سرعت جابه جایی ساختارهای گردابه ای؛ طول مشخصه در راستای دهانه | ||
| عنوان مقاله [English] | ||
| Semi-empirical Investigation of Trailing Edge Noise by Measuring Unsteady Surface Pressures | ||
| نویسندگان [English] | ||
| abbas afshari1؛ Ali Akbar Dehghan2؛ mohammad farmani3 | ||
| 1phd student / yazd university | ||
| 3phd student/ yazd university | ||
| چکیده [English] | ||
| Turbulent boundary layer trailing edge noise is one of the main sources of aerodynamic noise and extensive studies have been devoted to trailing edge noise identification during the past decades. In the present study, for measuring the main parameters affecting the trailing edge noise including the surface pressure spectra, the spanwise length scale of the surface pressure fluctuations and eddy convection velocity in the trailing edge region, a flat-plate model equipped with several streamwise and spanwise surface pressure transducers is designed and built. The spanwise length scale and eddy convection velocity are calculated by simultaneously measuring of unsteady surface pressure in both streamwise and spanwise directions. The results show that the best collapses in the surface pressure spectra at low frequency and mid to high frequencies can be obtained by using outer and inner layer scales respectively. Furthermore, the longitudinal and lateral coherences can provide adequate information about the lifespan of the turbulent eddies and their physical size. Finally, the far-field trailing edge noise induced by the turbulent flow over the flat plate has been predicted by using the Amit-Roger model and results show the effectiveness of this model for prediction of far-field turbulent boundary layer trailing edge noise. | ||
| کلیدواژه‌ها [English] | ||
| Trailing edge noise, Turbulent boundary layer, Surface pressure spectra, Eddy convection velocity, Spanwise length scale | ||
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| مراجع | ||
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