Gemi Kesiti için Yalpa Merkezi Konumunun Yalpa Sönümüne Etkisi

Viskoz yalpa sönümünün doğru olarak hesaplanması gemilerin yalpa hareketinin analizi için önemlidir. Zorlanmış yalpa testi veya serbest bırakma testi uygulanarak gemilerin viskoz yalpa sönümü deneysel ve sayısal olarak hesaplanabilir. Ayrıca deneysel veriler kullanılarak geliştirilen yarı ampirik formüller de viskoz yalpa sönümü tahmininde kullanılabilir. Bu çalışmada bir gemi orta kesiti için yalpa merkezi konumunun yalpa sönümüne etkisi deneysel, sayısal ve Ikeda yarı ampirik metoduyla incelenmiştir. Yalpa merkezinin dikine konumu kaide hattı ve güverte hattı arasında değiştirilmiştir. Yalpa sönüm katsayıları yalpa omurgaya sahip bir gemi orta kesitine zorlanmış yalpa testi uygulanarak deneysel ve sayısal (HAD yöntemi) olarak hesaplanmıştır. Ayrıca Ikeda tarafından önerilen yarı ampirik formül ile de sonuçlar karşılaştırılmıştır. Sayısal sonuçların deneyler ile uyum içinde olduğu ve Ikeda metodundan daha yaklaşık sonuçlar verdiği görülmüştür

Effect of the Roll Center Position on the Roll Damping of a Ship Section

The accurate calculation of the viscous roll damping is important for the estimation of the ship roll motion. Viscous roll damping can be calculated experimentally or numerically using forced roll oscillation or free roll decay tests. Semi-empirical formulae derived from experiment data can also be used for the prediction of viscous roll damping. In this study, the effect of the roll center position on the roll damping of a ship midsection was investigated experimentally, numerically and by using Ikeda’s semi-empirical method. The vertical position of the roll center were shifted from near-bottom to main deck level of the ship section. The roll damping coefficients were obtained experimentally and numerically (CFD) by applying forced oscillation tests to the ship midsection with bilge keels. Semi-empirical Ikeda method was also used for the comparison of the results. It was observed that the numerical results are in good agreement with experimental results and the estimation of roll damping with numerical method is better than Ikeda method.

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