Yarı Küresel Burunlu Torpido Benzeri Geometri Etrafındaki Akışın POD Analizi

Öz

Geçtiğimiz on yılda geniş bir uygulama yelpazesine sahip su altı araçlarına ilgi artmıştır. Bu çalışmada, Myring profiline sahip ortak, torpido benzeri bir geometri etrafındaki akış özellikleri, Parçacık Görüntüleme Hız Ölçme (PIV) yöntemi kullanılarak geometri boyuna göre tanımlanan Reynolds sayısının Re=20000 değerinde incelenmiştir. Bu çalışmada PIV ve Uygun Orthogonal Ayrıştırma (POD) analizleri sonucunda; anlık akım çizgisi topolojisi Ψ, anlık girdap ωL⁄U_∞ konturları, anlık akış yönünde hız bileşeni u⁄U_∞ grafikleri, çapraz akış yönünde hız bileşeni v⁄U_∞ grafikleri, anlık girdap ωL⁄U_∞ grafikleri, akış yönüne dik, anlık girdap grafikler ve zaman ortalamalı TKE grafikleri değerlendirildi ve karşılaştırıldı. Aynı zamanda PIV analizi sonucunda zaman ortalamalı akım çizgisi topolojisi <Ψ> ve Zaman ortalamalı girdap <ωL⁄U_∞ > kontur değerleri verilmiştir. POD yöntemini kullanarak elde ettiğimiz akış özelliklerini PIV sonuçlarıyla karşılaştırdığımızda POD verilerinin genel olarak PIV sonuçlarına oldukça benzer olmasına rağmen POD analiz sonuçlarının daha düzgün bir yapıya sahip olduğu ve girdap türbülansının daha az olduğu belirlendi.

Anahtar Kelimeler

• PIV
• POD
• Yarı küresel burun
• Torpido benzeri geometri
• Türbülanslı akış
• Girdaplı akış

POD Analysis of Flow around Torpedo-Like Geometry with a Hemispherical Nose

Abstract

There has been an increased interest in underwater vehicles for a wide range of applications over the past decade. In the current study, flow characteristics around a common, torpedo-like geometry with a Myring profile were investigated at a length-based Reynolds number of Re=20000 using the Particle Image Velocimetry (PIV). As a result of PIV and Proper Orthogonal Decomposition (POD) analyzes in this study; instantaneous streamline topology Ψ, instantaneous vorticity ωL⁄U_∞ contours, instantaneous streamwise velocity component u⁄U_∞ graphs, cross-streamwise velocity component v⁄U_∞ graphs, instantaneous vorticity ωL⁄U_∞ graphs, perpendicular to the flow direction, instantaneous vortex graphs and time-averaged TKE graphs were evaluated and compared. At the same time, as a result of PIV analysis, time-average streamline topology <Ψ> and Time-averaged vorticity <ωL⁄U_∞ > contours values are given. When the flow characteristics were compared by using the obtained POD method of the PIV results, it was determined that although the POD data were generally quite similar to the PIV results, the POD analysis results had a more uniform flow structure and vortex turbulence was lessened.

Keywords

• PIV
• POD
• Hemispherical nose
• Torpedo-like geometry
• Turbulent-flow
• Vortical flow

Kaynakça

1. Anonymous. Dynamic Studio software of the Dantec Dynamics, https://www.dantecdynamics.com (Access 13.11.2023), 2016.
2. Akbudak E., Yanıktepe B., Şekeroğlu E., Kenan Ö., Ozgoren M. Investigation of the flow structures for two tandem arrangement of torpedo-like geometries. Osmaniye Korkut Ata Üniversitesi Fen Bilimleri Enstitüsü Dergisi 2022a; 1(5): 135-155.
3. Akbudak E., Şekeroğlu E., Yaniktepe B., Kenan Ö., Özgören M. Investigation of flow characteristics around a blunt nose and conical stern geometry with single and tandem arrangements. UNEC Journal of Engineering and Applied Sciences 2022b; 2(2): 49-55.
4. Berkooz G., Holmes P., Lumley JL. The proper orthogonal decomposition in the analysis of turbulent flows. Annu Rev Fluid Mech 1993; 25: 539-575.
5. de Barros EA., Dantas JLD, Pascoal AM. de S ´a E. Investigation of normal force and moment coefficients for an AUV at nonlinear angle of attack and sideslip range. Journal of Oceanic Eng 2008; 33(4): 538-549.
6. Desa E., Madhan R., Maurya P. Potential of autonomous underwater vehicles as new generation ocean data platforms. Current Science 2006; 90(9): 1202-1209.
7. Durhasan T. Flow topology downstream of the hollow square cylinder with slots. Ocean Eng, 2020; 209: 107518.
8. Kilavuz A., Ozgoren M., Kavurmacioğlu LA., Durhasan T., Sarigiguzel F., Sahin B., Akilli H., Sekeroglu E., Yaniktepe B. Flow characteristics comparison of PIV and numerical prediction results for an unmanned underwater vehicle positioned close to the free surface. Applied Ocean Research 2022a; 129: 103399.

9. Kilavuz A., Durhasan T., Ozgoren M., Sarigiguzel F., Sahin B., Kavurmacioğlu LA., Akilli H., Sekeroglu, E., Yaniktepe B. Influence of free-surface on wake flow characteristics of a torpedo-like geometry. Journal of Marine Science and Technology 2022b; 27(3): 1130-1147.
10. Kilavuz A., Sarigiguzel F., Ozgoren M., Durhasan T., Sahin B., Kavurmacioğlu LA., Akilli H., Sekeroglu E., Yaniktepe B. The impacts of the free-surface and angle of attack on the flow structures around a torpedo-like geometry. European Journal of Mechanics-B/Fluids 2022c; 92: 226-243.
11. Kenan O., Yanıktepe B., Sekeroglu E., Akbudak E., Ozgoren M. Experimental investigation of instantaneous flow properties around a hemispherical nose torpedo-like geometry exposed to üniform flow. 4. International Baku Scientific Research Congress, 30 November-01 December 2022a, page number:542-551, Baku.
12. Kenan O.,Yanıktepe B., Sekeroglu E., Akbudak E., Ozgoren M. Experimental investigation of instantaneous flow properties around a cambered nose torpedo-like geometry exposed to üniform flow. 3. International Cappadocia Scientific Research Congres, 11-12 December 2022b, page number: 884-894, Nevşehir.
13. Kenan O.,Yanıktepe B., Sekeroglu E., Akbudak E., Ozgoren M. Experimental investigation of instantaneous flow properties around a hemispherical nose, 3-wing torpedo-like geometry positioned in smooth flow conditions. 1. Uluslararası Boğaziçi Bilimsel Çalışmalar Kongresi, 13-14 May 2023, page number:444-454, İstanbul.
14. Kumley JL. The structure of inhomogeneous turbulent flow. In: Yaglom AM, Tatarski VI (eds) Atmospheric turbulence 1967.
15. Meyer KE., Pedersen JM., Ozcan O. A turbulent jet in crossflow analysed with proper orthogonal decomposition. J. Fluid Mech 2007; 583: 199–227.
16. Myring, DF. Theoretical study of body drag in subcritical axisymmetric flow 1976; 27: 186–194.
17. Noack BR., Morzynski M., Tadmor G. Reduced-order modeling for flow control. CISM courses and lectures. No. 528. Springer; 2010.