Vertical-Plane Dynamics of Power-Augmented-Ram Vehicle

2013 ◽  
Author(s):  
Konstantin I. Matveev
Keyword(s):  
Control Systems ◽  
High Speed ◽  
Dynamic Models ◽  
Vertical Plane ◽  
Ground Effect ◽  
Forward Speed ◽  
Unsteady Forces ◽  
Wind Gusts ◽  
Strip Theory ◽  
Effect Theory

Power-augmented-ram vehicles represent novel air-assisted marine craft that can be used for high-speed amphibious transportation of heavy cargo. These vehicles rely on combined hydrodynamic and aerodynamic support that is also augmented by front air-based propulsors. Dynamic models for these craft in the presence of wind gusts and surface waves are needed for confident design of these vehicles, including motion control systems. This study addresses 3-DOF vertical-plane dynamics. The models for unsteady forces are based on the aerodynamic extreme-ground-effect theory and hydrodynamic added-mass strip theory. Modeling of the vehicle motions are carried out for cases of head and following wind gusts and waves of low and high amplitudes. Simulation results can be used for determining amplitudes of the vehicle responses, peak accelerations, and forward speed degradation.

Response Surface Models for Analyzing Planing Hull Motions in a Vertical Plane

2014 ◽  
Author(s):  
Tanvir Mehedi Sayeed ◽  
Leonard M. Lye ◽  
Heather Peng
Keyword(s):  
High Speed ◽  
Uniform Design ◽  
Vertical Plane ◽  
Statistical Design ◽  
Surrogate Models ◽  
Center Of Gravity ◽  
Design Parameters ◽  
Strip Theory ◽  
Calm Water ◽  
Sinkage And Trim

A non-linear mathematical model, Planing Hull Motion Program (PHMP) has been developed based on strip theory to predict the heave and pitch motions of planing hull at high speed in head seas. PHMP has been validated against published model test data. For various combinations of design parameters, PHMP can predict the heave and pitch motions and bow and center of gravity accelerations with reasonable accuracy at planing and semi-planing speeds. This paper illustrates an application of modern statistical design of experiment (DOE) methodology to develop simple surrogate models to assess planing hull motions in a vertical plane (surge, heave and pitch) in calm water and in head seas. Responses for running attitude (sinkage and trim) in calm water, and for heave and pitch motions and bow and center of gravity accelerations in head seas were obtained from PHMP based on a multifactor uniform design scheme. Regression surrogate models were developed for both calm water and in head seas for each of the relevant responses. Results showed that the simple one line regression models provided adequate fit to the generated responses and provided valuable insights into the behaviour of planing hull motions in a vertical plane. The simple surrogate models can be a quick and useful tool for the designers during the preliminary design stages.

A Linear Model Analysis of the Unsteady Force Response of a Planing Hull Through Forced Vertical Plane Motion Simulations

2020 ◽  
Author(s):  
Nicholas Husser ◽  
Stefano Brizzolara
Keyword(s):  
Linear Model ◽  
High Speed ◽  
Vertical Plane ◽  
Added Mass ◽  
Plane Motion ◽  
Force Response ◽  
Strip Theory ◽  
Planar Motion Mechanism ◽  
Unsteady Force ◽  
Traditional Approaches

The prediction of planing hull motions and accelerations in a seaway is of paramount importance to the design of high-speed craft to ensure comfort and, in extreme cases, the survivability of passengers and crew. The traditional approaches to predicting the motions and accelerations of a displacement vessel generally are not applicable, because the non-linear effects are more significant on planing hulls than displacement ships. No standard practice for predicting motions or accelerations of planing hulls currently exists, nor does a nonlinear model of the hydrodynamic forces that can be derived by simulation. In this study, captive and virtual planar motion mechanism (VPMM) simulations, using an Unsteady RANSE finite volume solver with volume of fluid approach, are performed on the Generic Prismatic Planing Hull (GPPH) to calculate the linearized added mass, damping, and restoring coefficients in heave and pitch. The linearized added mass and damping coefficients are compared to a simplified theory developed by Faltinsen [6], which combines the method of Savitsky [12] and 2D+t strip theory. The non-linearities in all coefficients will be investigated with respect to both motion amplitude and frequency. Nonlinear contributions to the force response are discussed through comparison of the force response predicted by the linear model and force response measured during simulation. Components of the planing hull dynamics that contribute to nonlinearities in the force response are isolated and discussed.

STATIC STABILITY OF AERODYNAMICALLY SUPPORTED PLATFORMS MOVING ABOVE WATER

2021 ◽  
Vol 153 (A3) ◽  
Author(s):  
K I Matveev
Keyword(s):  
High Speed ◽  
Stability Margin ◽  
Ground Effect ◽  
Aerodynamic Characteristics ◽  
Static Stability ◽  
Underlying Surface ◽  
Geometrical Parameters ◽  
Marine Vehicles ◽  
Effect Theory ◽  
Rigid Plane

The motion stability is the most important problem of high-speed marine vehicles that utilize aerodynamic support. A simplified analysis and calculations of longitudinal static stability of several basic platforms moving above water are carried out in this study. The analysis is based on the extreme ground effect theory and the assumption of hydrostatic deformations of the water surface. Effects of the underlying surface type, Froude number, and several geometrical parameters on main aerodynamic characteristics, including the static stability margin, are presented. If the underlying surface is water instead of a rigid plane, the static stability worsens for platforms with flat or S-shaped lower surfaces, but it slightly improves for a horizontal platform with a flap. The static stability margin remains positive for S-shaped profiles at sufficiently low Froude numbers, while it is negative for other configurations.

Nonlinear Impact Loading in an Oblique Seaway

2003 ◽  
Vol 125 (3) ◽  
pp. 190-197 ◽  
Author(s):  
Patrick J. Finn ◽  
Robert F. Beck ◽  
Armin W. Troesch ◽  
Yung Sup Shin
Keyword(s):  
Time Domain ◽  
High Speed ◽  
Dynamic Instability ◽  
Vertical Plane ◽  
Direct Calculation ◽  
Wave Loads ◽  
Nonlinear Method ◽  
Strip Theory ◽  
The Impact ◽  
Flare Slamming

There is an increasing interest in developing direct calculation methods and procedures for determining extreme wave loads on ship girders (e.g. ISSC, 2000 [1]). Ships experiencing bottom and bow flare slamming have heightened the need for computational tools suitable to accurately predict motion and structural responses. The associated nonlinear impact problem is complicated by the complex free surface and body boundary conditions. This paper examines a “blended” linear–nonlinear method by which extreme loads due to bottom impact and flare slamming can be determined. Using a high-speed container ship as an example, comparisons of motions, shear and bending moments, and pressures are made in head and oblique bow-quartering waves. The time-domain computer program used in the comparison is based upon partially nonlinear models. The program, NSHIPMO, is an blended strip theory method using “impact” stations over the forward part of the ship and partially nonlinear stations over the rest. Body exact hydrostatics and Froude-Krylov excitation are used over the entire hull. The impact theory of Troesch and Kang [2] is employed to estimate the sectional nonlinear impact forces acting upon the specified nonlinear sections, while the linear theory of Salvesen et al. (STF) [3] is used to blend the remainder of the hydrodynamic forces, that is the radiation and diffraction components. Results from the simulation are presented with discussions of accuracy and time of computation. Several issues associated with the blended nonlinear time-domain simulation are presented, including modeling issues related to directional yaw-sway control and a vertical plane dynamic instability in long waves that has not previously been recognized.

Smart Control Systems for Next-Generation Autonomous Wing-In-Ground Effect Vehicles

2010 ◽  
Vol 43 (15) ◽  
pp. 112-117 ◽  
Author(s):  
Alexander Nebylov ◽  
Sukrit Sharan ◽  
Farid Arifuddin
Keyword(s):  
Control Systems ◽  
Ground Effect ◽  
Next Generation ◽  
Smart Control ◽  
Wing In Ground Effect

Rotor-Dynamics of Different Shaft Configurations for a 6 kW Micro Gas Turbine for Concentrated Solar Power

2016 ◽  
Author(s):  
A. Arroyo ◽  
M. McLorn ◽  
M. Fabian ◽  
M. White ◽  
A. I. Sayma
Keyword(s):  
Gas Turbines ◽  
High Speed ◽  
Dynamic Models ◽  
Solar Power ◽  
Critical Issue ◽  
Rotor Dynamics ◽  
Mode Shapes ◽  
Concentrated Solar Power ◽  
Element Analysis ◽  
Rotor Dynamic

Rotor-dynamics of Micro Gas Turbines (MGTs) under 30 kW have been a critical issue for the successful development of reliable engines during the last decades. Especially, no consensus has been reached on a reliable MGT arrangement under 10 kW with rotational speeds above 100,000 rpm, making the understanding of the rotor-dynamics of these high speed systems an important research area. This paper presents a linear rotor-dynamic analysis and comparison of three mechanical arrangements of a 6 kW MGT intended for utilising Concentrated Solar Power (CSP) using a parabolic dish concentrator. This application differs from the usual fuel burning MGT in that it is required to operate at a wider operating speed range. The objective is to find an arrangement that allows reliable mechanical operation through better understanding of the rotor dynamics for a number of alternative shaft-bearings arrangements. Finite Element Analysis (FEA) was used to produce Campbell diagrams and to determine the critical speeds and mode shapes. Experimental hammer tests using a new approach based on optical sensing technology were used to validate the rotor-dynamic models. The FEA simulation results for the natural frequencies of a shaft arrangement were within 5% of the measurements, while the deviation for the shaft-bearings arrangement increased up to 16%.

Analysis, Design, and Optimization of High Speed Vehicle Suspensions Using State Variable Techniques

1974 ◽  
Vol 96 (2) ◽  
pp. 193-203 ◽  
Author(s):  
J. K. Hedrick ◽  
G. F. Billington ◽  
D. A. Dreesbach
Keyword(s):  
High Speed ◽  
Optimization Problems ◽  
Vertical Plane ◽  
Computer Application ◽  
Vehicle Suspension ◽  
State Variables ◽  
State Variable ◽  
Suspension Parameters ◽  
Suspension Model ◽  
High Speed Vehicle

This article applies state variable techniques to high speed vehicle suspension design. When a reasonably complex suspension model is treated, the greater adaptability of state variable techniques to digital computer application makes it more attractive than the commonly used integral transform method. A vehicle suspension model is developed, state variable techniques are applied, numerical methods are presented, and, finally, an optimization algorithm is chosen to select suspension parameters. A fairly complete bibliography is included in each of these areas. The state variable technique is illustrated in the solution of two suspension optimization problems. First, the vertical plane suspension of a high speed vehicle subject to guideway and aerodynamic inputs will be analyzed. The vehicle model, including primary and secondary suspension systems, and subject to both heave and pitch motions, has thirteen state variables. Second, the horizontal plane suspension of a high speed vehicle subject to guideway and lateral aerodynamic inputs is analyzed. This model also has thirteen state variables. The suspension parameters of both these models are optimized. Numerical results are presented for a representative vehicle, showing time response, mean square values, optimized suspension parameters, system eigenvalues, and acceleration spectral densities.

Dynamics and Stability of Boats With Aerodynamic Support

2013 ◽  
Vol 29 (01) ◽  
pp. 17-24
Author(s):  
Konstantin I. Matveev ◽  
Nikolai Kornev
Keyword(s):  
Ground Effect ◽  
Ground Vehicles ◽  
Marine Transportation ◽  
Technical Problems ◽  
Transient Regimes ◽  
High Speeds ◽  
Effect Theory ◽  
Stability Issues ◽  
Marine Vehicle ◽  
Very High

Aerodynamic support is beneficial for achieving very high speeds of marine transportation. Wing-in-ground vehicles, power-augmented ram platforms, and ultrafast planing multihulls are examples of marine craft with air assistance. The main technical problems in the development and application of these concepts for marine transportation are to ensure motion stability and to provide adequate seaworthiness. In this article, we illustrate applications of several mathematical models for various air supported marine vehicle concepts and discuss their specific stability issues. The aerodynamic submodels are based on nonlinear vortex-lattice methods and on the extreme ground effect theory, whereas unsteady hydrodynamics of planing surfaces are treated with added-mass strip theories. The static and dynamic stability in the vicinity of equilibrium states can be analyzed by linearized approaches. However, motions in transient regimes and unsteady environments require implementation of nonlinear and fully unsteady modeling methods.

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