Airwake Control of ONR Tumblehome Using CVG

Abstract

Ship aerodynamics studies are increasing in recent years due to the developments in aerodynamic design of the ships. Ship superstructures are designed carefully for better performance of systems and sensors located on the superstructure. Also ship-helicopter interaction comes into mind when the ship has a flight deck for landing and take-off operations. In this study, a comprehensive validation of ship airwake was made for the well-known benchmark model, ONR Tumblehome (ONRT), in model scale. Numerical analyses were carried out solving the unsteady RANS equations with hexahedral finite volume elements. Atmospheric boundary layer (ABL) was used to create more realistic velocity profile in the computational domain. Following the validation, columnar vortex generators (CVG) were designed and integrated to the ship superstructure as the passive controller of the airwake. Impressive healing on the airwake was observed when CVG is located on the ship. The use of appropriate CVG geometry shortened the recirculation region and the reattachment length. This finding leads to lower turbulence intensity and fluctuations over the flight deck.

Keywords

• ABL
• Airwake
• Columnar Vortex Generator
• URANS

ONRT Formunun Hava İzinin CVG Kullanarak Kontrolü

Abstract

Gemilerin aerodinamik tasarımındaki gelişmelerle birlikte, gemi aerodinamiği çalışmaları son yıllarda artış göstermektedir. Gemi üst yapıları, üst yapıda bulunan sistemlerin ve sensörlerin daha iyi performans göstermesi için titizlikle tasarlanmaktadır. Ayrıca, geminin iniş ve kalkış operasyonları için bir uçuş güvertesine sahip olduğu durumlarda, gemi-helikopter etkileşimi de ön plana çıkmaktadır. Bu çalışmada, iyi bilinen bir kıstas model olan ONRT’nin model ölçeğindeki hava izi yapısının kapsamlı bir doğrulaması yapılmıştır. Sayısal analizler, altı yüzlü sonlu hacim elemanları kullanılarak zamana bağlı RANS denklemlerinin çözülmesiyle gerçekleştirilmiştir. Hesaplama alanında daha gerçekçi bir hız profili oluşturmak amacıyla Atmosferik Sınır Tabaka (ABL) modeli kullanılmıştır. Doğrulama çalışmalarının ardından, hava akımının pasif kontrolcüsü olarak sütunlu girdap üreteci (CVG) tasarlanmış ve gemi üst yapısına entegre edilmiştir. CVG’lerin gemi üzerine yerleştirilmesiyle hava izi yapısında kayda değer bir iyileşme gözlemlenmiştir. Uygun CVG geometrisinin kullanımı, geri akış bölgesini ve yeniden tutunma uzunluğunu kısaltmıştır. Bu bulgu, uçuş güvertesi üzerindeki türbülans yoğunluğunun ve dalgalanmaların azalmasını sağlamaktadır.

Keywords

• ABL
• Hava izi
• Sütunlu Girdap Üreteci
• URANS.

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