The Experts below are selected from a list of 231 Experts worldwide ranked by ideXlab platform

Yasuaki Kuroe - One of the best experts on this subject based on the ideXlab platform.

Daniel Fonseca De Carvalho E Silva - One of the best experts on this subject based on the ideXlab platform.

  • Directional Stability of the torpedo anchor pile during its installation
    The IES Journal Part A: Civil & Structural Engineering, 2011
    Co-Authors: Antonio Carlos Fernandes, Daniel Fonseca De Carvalho E Silva, Joel S. Sales, Gustavo R. Diederichs
    Abstract:

    The so-called torpedo anchoring system is a novel and yet already intensively field-proven by Petrobras (the Brazilian oil company) offshore, Brazil. It is a pile with a specific elongated form that is buried in the sea bottom to hold mooring lines that are connected to floating production units. This is so even for very deep water (typically 1800 m). The methodology of installation of the torpedo pile so far consists of a vertical launching, starting with the torpedo above and close (typically 100 m) to the sea bottom. This installation path then occurs from the pile at the starting position with zero velocity until it reaches the bottom. During this installation, the pile travels almost freely, only dragging the mooring line. It is obvious that the object has to have a minimum Directional Stability to arrive vertically at the bottom. The pile becomes useless when it gets a vertical angle that is outside certain limits (typically three degrees). The present article addresses the Directional Stability of ...

  • CFD Hydrodynamic Analysis of a Torpedo Anchor Directional Stability
    29th International Conference on Ocean Offshore and Arctic Engineering: Volume 6, 2010
    Co-Authors: Daniel Fonseca De Carvalho E Silva
    Abstract:

    The geometry of offshore anchors is usually determined from a geotechnical perspective. This paper presents the proposal of simple modifications on a torpedo anchor to improve its hydrodynamic performance concerning its Directional Stability. Additionally, the study of a real case torpedo deformation is presented. Although the Directional Stability investigation requires a dynamic analysis, the CFD simulations were performed on a steady state regime to show for which inclinations the anchor tends to recover the vertical position. The trajectory was investigated through a simplified dynamic model and compared with field measurements.Copyright © 2010 by ASME

Keishi Kawabata - One of the best experts on this subject based on the ideXlab platform.

Danilo Ciliberti - One of the best experts on this subject based on the ideXlab platform.

  • Aircraft Directional Stability and vertical tail design: A review of semi-empirical methods
    Progress in Aerospace Sciences, 2017
    Co-Authors: Danilo Ciliberti, Pierluigi Della Vecchia, Fabrizio Nicolosi, Agostino De Marco
    Abstract:

    Aircraft Directional Stability and control are related to vertical tail design. The safety, performance, and flight qualities of an aircraft also depend on a correct empennage sizing. Specifically, the vertical tail is responsible for the aircraft yaw Stability and control. If these characteristics are not well balanced, the entire aircraft design may fail. Stability and control are often evaluated, especially in the preliminary design phase, with semi-empirical methods, which are based on the results of experimental investigations performed in the past decades, and occasionally are merged with data provided by theoretical assumptions. This paper reviews the standard semi-empirical methods usually applied in the estimation of airplane Directional Stability derivatives in preliminary design, highlighting the advantages and drawbacks of these approaches that were developed from wind tunnel tests performed mainly on fighter airplane configurations of the first decades of the past century, and discussing their applicability on current transport aircraft configurations. Recent investigations made by the authors have shown the limit of these methods, proving the existence of aerodynamic interference effects in sideslip conditions which are not adequately considered in classical formulations. The article continues with a concise review of the numerical methods for aerodynamics and their applicability in aircraft design, highlighting how Reynolds-Averaged Navier-Stokes (RANS) solvers are well-suited to attain reliable results in attached flow conditions, with reasonable computational times. From the results of RANS simulations on a modular model of a representative regional turboprop airplane layout, the authors have developed a modern method to evaluate the vertical tail and fuselage contributions to aircraft Directional Stability. The investigation on the modular model has permitted an effective analysis of the aerodynamic interference effects by moving, changing, and expanding the available airplane components. Wind tunnel tests over a wide range of airplane configurations have been used to validate the numerical approach. The comparison between the proposed method and the standard semi-empirical methods available in literature proves the reliability of the innovative approach, according to the available experimental data collected in the wind tunnel test campaign.

  • An improved preliminary design methodology for aircraft Directional Stability prediction and vertical tailplane sizing
    2016
    Co-Authors: Danilo Ciliberti
    Abstract:

    This work deals with the development of a new preliminary design method for aircraft Directional Stability and vertical tail sizing. It is focused on regional turboprop aircraft because of their economic advantage over regional jets on short routes, for the increasing oil price, and because of the market needs of new airplanes in the next 20 years. The focus on aircraft Directional Stability is due to the significant discrepancies that classical semi-empirical methods, as USAF DATCOM and ESDU, provide for some configurations, because they are based on NACA wind tunnel tests about models not representative of an actual transport airplane. This work exploits the CFD to calculate the aerodynamic interference among aircraft parts for hundreds configurations of a given layout, providing a useful method in aircraft preliminary design. A wind tunnel investigation involving about 180 configurations has validated the numerical approach. The innovation of the work concerns the numerical and experimental parametric study on the static Directional Stability of a model representative of the regional turboprop aircraft category and the direct measurement of the vertical stabilizer aerodynamic forces in the wind tunnel, in addition to the force and moments acting on the whole model. In this way, useful data about aerodynamic interference have been extracted from experimental tests, which are in good agreement with the results of numerical simulations.

  • Aircraft Directional Stability prediction method by CFD
    33rd AIAA Applied Aerodynamics Conference, 2015
    Co-Authors: Pierluigi Della Vecchia, Fabrizio Nicolosi, Danilo Ciliberti
    Abstract:

    The aim of this paper is to present a new method to predict aircraft Directional characteristics. The proposed approach is completely CFD based and it has been developed with more than 300 simulations of complete and partial aircraft configurations. The method accounts for mutual aerodynamic interference effects among components. First, the isolated vertical tailplane and fuselage yawing moment coefficients are calculated. Then, correction factors are applied to take into account for aircraft components (fuselage, wing, vertical and horizontal tailplanes). The corrected yawing moment coefficients represent the contributions of vertical tailplane and fuselage to aircraft Directional Stability, including the aerodynamic interference among all aircraft components. Finally, the method is tested and compared to typical semi-empirical approaches (USAF DATCOM, ESDU).

Takehiro Mori - One of the best experts on this subject based on the ideXlab platform.