In recent years Hardware-in-the-Loop HiL, has gained more and more popularity within the vehicle industry. This is a more cost effective research alternative, as opposed to the tests done the traditional way, since in HiL testing the idea is to test the hardware of interest, such as an electronic control unit, in a simulated (or partially simulated) environment which closely resembles the real-world environment. This thesis is ordered by Daimler Chrysler AG and the objective of this thesis is the developing of a cylinder-by-cylinder model for the purpose of emulation of misfire in a four-stroke SI-engine. This purpose does not demand a precise modelling of the cylinder pressure but rather an adequate modelling of position and amplitude of the torque produced by each cylinder. The model should be preferebly computaionally tractable so it can be run on-line. Therefore, simplifications are made such as assuming the rule of a homogenous mixture, pressure and temperature inside the cylinder at all steps, so the pressure model can be analytical and able to cope with the real-time demand of the HiL. The model is implemented in Simulink and simulated with different sample rates and an improvement is to be seen as the sample rate is decreased.

The residual gas fraction is an important parameter to get good performance with high efficiency and low emissions in the HCCI-engine. The goal in this thesis is to formulate an algorithm for estimation of the residual gas fraction based on the cylinder pressure. The estimation is improved if also the exhaust gas temperature is used together with the cylinder pressure. The formulated algorithm has then been tested on data from a single cylinder engine running in HCCI-mode during steady state conditions. An error of 4% was noted compared with the residual gas fraction obtained from simulations. The thesis also investigates the effects of some possible error sources.

The steady problem of free convective heat transfer from an isothermal inclined elliptic cylinder and its stability is investigated. The cylinder is inclined at an arbitrary angle with the horizontal and immersed in an unbounded, viscous, incompressible fluid. It is assumed that the flow is laminar and two-dimensional and that the Boussinesq approximation is valid. The full steady Navier-Stokes and thermal energy equations are transformed to elliptical co-ordinates and an asymptotic analysis is used to find appropriate far-field conditions. A numerical scheme based on finite differences is then used to obtain numerical solutions. Results are found for small to moderate Grashof and Prandtl numbers, and varying ellipse inclinations and aspect ratios. <br /><br /> A linear stability analysis is performed to determine the critical Grashof number at which the flow loses stability. Comparisons are made with long-time unsteady solutions.

<p>In modern engineering there is a considerable interest in predicting the behavior of post-buckled structures. With current lightweight, aerospace, and high performance applications, structural elements frequently operate beyond their buckled load. This is especially true of plates, which are capable of maintaining stability at loads several times their critical buckling load. Additionally, even structures such as cylindrical shells may be pushed into a post-buckled range in these extreme applications. </p><p>Because of the nature of these problems, continuation methods are particularly well suited as a solution method. Continuation methods have been extensively applied to a range of problems in mathematics and physics but have been used to a lesser extent in engineering problems. In the present work, continuation methods are used to solve a variety of buckling and stability problems of discrete dynamical systems, plates and cylinders. The continuation methods, when applied to dynamic mechanical systems, also provide very useful information regarding the modal behavior of the structure, including linearized natural frequencies and mode shapes as a by-product of the solution method.</p><p>To verify the results of the continuation calculations, the commercial finite element code ANSYS is used as an independent check. To confirm previously unseen stable equilibrium shapes for square plates, a set of experiments on polycarbonate plates is also presented.</p> / Dissertation

This thesis is an experimental study of shear effect of a two-degree-of-freedom cylinder in fluid flow in terms of different mass ratio. This study is done using an elastic cylinder of high natural frequency, and the free stream velocity is 0.2m/s to 1.5m/s. The results show that as mass ratio increases, the motion of cylinder becomes more stable and small, and the frequency response of cylinder self-excited is bigger than vortex-shedding response when spring constant is bigger enough. Thus it is not easy to observe the vortex-shedding frequency variation with respect to various velocities by dint of cylinder vibration. When it come to the shear effect, the effect of shear flow could decreases the drag force, and increases the lift force. Orbits of cylinder vibration is not symmetric; the displacement is more significant on low velocity side.

Elastic cylinder vibration due to different shear parameter in the water flow is investigated experimentally in this research. The water flow ranges from 0.4 m/s to 1.06 m/s. It is found from the experiment that shear parameter has a significant influence on the amplitude of the cylinder vibration. The greater the shear parameter becomes, the later the delaying phenomenon also becomes. The delaying phenomenon will bring about resonant procrastination. Additionally, the greater shear parameter lessens the cylinder¡¦s drag force, but the lift force will be augmented, and the vibration orbit will be asymmetric. At lower flow velocity, cylinder¡¦s displacement is greater. With the enhancement of the shear parameter or the reduced velocity, the flow type and the vortex street behind the cylinder will turn more and more impalpable, and eventually become chaotic.

Vortex induced vibration of a circular cylinder in an inclined flow is a major subject in this thesis, the interaction and effect between a moving cylinder and fluid is always focused and investigated. We used a finite differences method to get the forces on cylinder, and then combined a Runge-Kutta four order approximate method to get a new position of a cylinder at next time step, repeated above procedure and we will get the solutions of a time series of cylinder response for VIV simulations. Most of papers focus on the peak amplitude and its scale due to the shedding frequency of system is near or at the fs, where fs is the shedding frequency of a uniform flow past a stationary cylinder. Except the ¡§first resonance¡¨, we found the ¡§second resonance¡¨ in the VIV simulations. The ¡§second resonance¡¨ occurs due to the natural shedding frequency of system is near or at the twice of the reduced frequency of the oscillator ¡§fs=2F1¡¨. The natural shedding frequency of a body is a key parameter, it always be discussed its effect and importance, and its value is also presented the frequency of lift force (or displacement on Y direction) of a body. On the contrary, the frequency of in-line force (or displacement on X direction) and its effect is seldom be investigated and discussed. In this study, we will discuss the effect of frequency of in-line force and the scale of ¡§first resonance¡¨ and ¡§second resonance¡¨ for VIV simulations. In order to verify the accuracy of our numerical model, this study simulated four different types for the cases of uniform flow past a circular cylinder with stationary, streamwise, transversal and rotational oscillating, respectively. The simulation results are compared with the study results of other paper by experimental and numerical methods, and the comparison show good agreement and high accuracy in the range of the in-line and lift forces on the cylinder, the main wake size behind the cylinder, the vortex shedding mode and the streamline pattern of the flow field. Furthermore, this study investigates a uniform flow past an inclined oscillating cylinder which is forcing oscillation in a range of 00 ~ 900 for the inclined angle (with respect to the X-direction of the Cartesian coordinates system). The effects of giving the different forced frequencies of a cylinder were investigated and discussed. And the application and restriction of Morison¡¦s equation will also be studied and investigated in different input conditions.

The present study aims to explore the dynamical behavior in the uniform flow by numerical method. The theoretical model is based on transient of continuity equation and momentum equation in CFD software: Fluent. With User Define Function¡]UDF¡^, we can simulate the Vortex-induced vibration¡]VIV¡^under the uniform flow by numerical method and plot the contour of amplitude and flow field under different Reynolds number. We will identify the accurate and capable of central difference method in UDF by comparing with the previous study. Also, we focus on whether the amplitude and flow situation will effect by uniform flow in different degrees or not. Furthermore, this study shows how the time step size and mesh effect the conclusion so that we could have the best choice on model.

Circular cylinders in cross-flow or the motion of circular cylinders in a fluid at rest are especially of interest in fields such as offshore and civil engineering or heat exchanger design in particular. A time-independent finite difference scheme, the basic equations are written in the form of the primitive-variable method, is developed to simulate the viscous flow across a streamwise oscillating circular cylinder. The mov-ing boundary of the oscillating cylinder is mapped to a fixed boundary and the boundary condition, therefore, becomes time independent. The finite difference ap-proximation and algorithm were first validated by the reported numerical simulation and flow visualization of the phenomenon £\ and phenomenon £] for a flow across a fixed circular cylinder. Detailed streamline patterns developed in the process are then described and discussed. Surface pressure distribution and position of separation point versus phases of various stationary and oscillating stages are discussed. The flow be-haviors of various amplitudes of exciting velocity and frequency of moving cylinder are simulated and compared. The relation between Keulegan-Carpenter and the drag force on cylinder during cylinder oscillation was also calculated under various Reynolds number.

In the past few decades, many people spent a lot of time and used many different ways, which includes analytic method, numerical method, and experimental observations for investigating the flow around circular cylinder problem. Eventually, the purpose of these investigations is to determinate the force acting on the cylinder and which is very useful and important for marine and hydraulic engineering. Essentially, it can be divided into three circumstances, (i) the flow around a fixed cylinder, (ii) the flow around a rotating cylinder, (iii) the flow around a moving cylinder. The first two conditions have already been will discussed. Consequently, besides analyzing the first two conditions and comparing with reference papers, the purpose of this present is discussing the variation of the flow field and the force acting on the cylinder by using finite difference method. Because of the considerable quantity of computation, using parallel computing for this model to speedup the numerical process is also one of the issues of the present.