<p>1D engine simulations of turbocharged engines are difficult to <!-- @page { size: 21cm 29.7cm; margin: 2cm } P { margin-bottom: 0.21cm } --></p><p>Techniques that can increase the SI- engine efficiency while keeping the emissions very low is to reduce the engine displacement volume combined with a charging system. Advanced systems are needed for an effective boosting of the engine and today 1D engine simulation tools are often used for their optimization.</p><p>This thesis concerns 1D engine simulation of a turbocharged SI engine and the introduction of CFD computations on components as a way to assess inaccuracies in the 1D model.</p><p>1D engine simulations have been performed on a turbocharged SI engine and the results have been validated by on-engine measurements in test cell. The operating points considered have been in the engine’s low speed and load region, with the turbocharger’s waste-gate closed.</p><p>The instantaneous on-engine turbine efficiency was calculated for two different turbochargers based on high frequency measurements in test cell. Unfortunately the instantaneous mass flow rates and temperatures directly upstream and downstream of the turbine could not be measured and simulated values from the calibrated engine model were used. The on-engine turbine efficiency was compared with the efficiency computed by the 1D code using steady flow data to describe the turbine performance.</p><p>The results show that the on-engine turbine efficiency shows a hysteretic effect over the exhaust pulse so that the discrepancy between measured and quasi-steady values increases for decreasing mass flow rate after a pulse peak.</p><p>Flow modeling in pipe geometries that can be representative to those of an exhaust manifold, single bent pipes and double bent pipes and also the outer runners of an exhaust manifold, have been computed in both 1D and 3D under steady and pulsating flow conditions. The results have been compared in terms of pressure losses.</p><p>The results show that calculated pressure gradient for a straight pipe under steady flow is similar using either 1D or 3D computations. The calculated pressure drop over a bend is clearly higher1D engine simulations of turbocharged engines are difficult to <!-- @page { size: 21cm 29.7cm; margin: 2cm } P { margin-bottom: 0.21cm } -->using 1D computations compared to 3D computations, both for steady and pulsating flow. Also, the slow decay of the secondary flow structure that develops over a bend, gives a higher pressure gradient in the 3D calculations compared to the 1D calculation in the straight pipe parts downstream of a bend.</p><p> </p>

Thesis (M.S.)--West Virginia University, 2003. / Title from document title page. Document formatted into pages; contains xiii, 93 p. : ill. (some col.), map (part col.). Includes abstract. Includes bibliographical references (p. 91-93).

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These photos are provided in order to more fully illustrate and explain the Zion and Pipe Spring technical report.

This research covers modeling of Electro Magnetic Acoustic Transducers (EMATs) and their application in excitation and detection of longitudinal guided Lamb wave modes for evaluation of flaws in cylindrical pipes. The combination of the configuration of transducers and the frequency of the input current is essential for successful excitation of desired guided wave modes and for proper interpretation of the results. In this study EMATs were successfully constructed and longitudinal modes L(0,1) and L(0,2) were excited in the pipe. From the recorded signals the level of simulated damage in pipes could be assessed. It is also possible to theoretically predict the location of the pipe flaws. Theoretical predictions are matched with experimental results. Dents and holes in pipes are detected by appropriate signal processing of received L(0,1) and L(0,2) modes.

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The Proceedings of the Twelfth East Asia-Pacific Conference on Structural Engineering and Construction : EASEC12

Horizontal directional drilling is increasingly used to install pipes without costs and disruptions associated with conventional ‘cut and cover’ installations. This technique, which was developed by industrial innovators, feature complex soil and pipe response which is not well understood. The success of this operation depends on knowledge of the pulling forces applied, level of ground disturbance, ground expansion or fracture from mud pressure, and the effect of the pulling operation on the pipes. Tensile stresses in the pipe vary with time during and after installation, and along the pipe. This applies especially to polymer pipes where the stresses during insertion and those over the service life of the pipe may influence its performance. The main objective of this study is to model the short term and long term response of pipes installed using horizontal directional drilling and to investigate the effect of the time dependent behaviour of polymer pipes, as well as other installation variables on the performance of the pipe during and after installation. The mechanical behaviour of high density polyethylene used to manufacture a significant portion of pipes installed using horizontal directional drilling is investigated and two sophisticated constitutive models are developed to simulate the time-dependent behaviour of high density polyethylene. The interaction between the pipe and the surrounding soil during horizontal directional drilling installations is also investigated and modelled. A FORTRAN algorithm is developed to calculate the short and long term response of elastic and polymeric pipes installed using horizontal directional drilling. The program uses the HDPE constitutive models as well as the pipe-soil interaction model developed in the study. After evaluation, the developed program is employed in a parametric study on the sensitivity of short term and long term pipe response to different parameters, including the effect of overstressing the pipe during installation. As Multiaxial modeling is necessary for accurate analysis of some applications including the swagelining method, a uniaxial constitutive model developed in the current study is generalized to a multi-axial model that can simulate the response to biaxial stress-strain fields. The multi-axial model is implemented in a finite element code and its performance in simulating multiaxial stress-strain fields is evaluated. / Thesis (Ph.D, Civil Engineering) -- Queen's University, 2008-06-12 18:03:43.501

This paper presents modifications to two widely used numerical groundwater flow models in an effort to improve upon the interaction between a well of finite length and conductivity with the surrounding formation. The first objective is to discard the common assumptions about flux- or head-based boundary conditions along the well screen by coupling pipe flow hydraulics and groundwater flow. The second objective is to avoid restricting the wellbore hydraulics to a single flow regime. Five flow regimes (laminar through rough-turbulent), based on Reynolds number and pipe roughness, are considered. The modifications are integrated into the highly versatile, well-documented and well-tested models HydroGeoSphere (finite-element/finite-difference) and USGS MODFLOW (finite-difference). Verification of the algorithm and code and is performed by comparing results to: 1) the idealized, analytical Theis solution; 2) the original, unmodified code; and 3) the results of a third party numerical solution that also accounts for variable frictional wellbore losses. Results highlight the inadequacy of either a uniform flux or a uniform head assumption along the wellbore. The solution also tends to produce much steeper hydraulic gradients in those portions of the aquifer nearest the pump intake than have previously been predicted. Systems most affected by in-well hydraulic losses include those for which well screen is long, pumping rate is large, pipe diameter is small, pipe roughness is large (either through design or aging) and aquifer conductivity is high. Improved modeling of the non-linear hydraulic conditions within the well screen can particularly influence the interpretation of wellbore flowmeter and tracer tests, leading to more precise knowledge of the variation of local aquifer hydraulic conductivity along well screens. Aquifer drawdown curves, solute transport and inflow velocities will also be influenced, which can impact capture zones and remediation costs. Given that the solution is incorporated within the HydroGeoSphere and MODFLOW models, it presents the additional advantage over existing approaches of offering a wide range of modeling capabilities, such as three-dimensional flow, arbitrary well inclination and surface-subsurface flow integration. / Thesis (Master, Civil Engineering) -- Queen's University, 2008-01-04 17:27:50.629

The main objective of this thesis is to study and investigate the dynamics and stability of cantilevered structures subjected to internal, external, or simultaneous internal and external axial flows. This was accomplished, in some cases, by deriving the linear equations of motion using a Newtonian approach and, in other cases, by making the necessary modifications to existing theoretical models. The continuous cantilevered systems were then discretized using the Galerkin method in order to determine their complex eigenfrequencies. Moreover, numerous experiments were performed to compare and validate, or otherwise, the theoretical models proposed. More specifically, the four cantilevered systems studied were the following: (i) a pipe conveying fluid that is fitted with a stabilizing end-piece, which suppresses flutter by blocking the straight-through exit of flow at the downstream end; (ii) a pipe aspirating fluid, which flutters at low flow velocities in its first mode; (iii) a free-clamped cylinder (i.e. with the upstream end free and the downstream end clamped) in confined axial flow, which also flutters at low flow velocities in its first mode and eventually develops a buckling instability; and (iv) a pipe subjected to internal flow, which after exiting the pipe is transformed to a confined counter-current annular flow, that becomes unstable by flutter too.