scholarly journals Computational Methodology for Knocking Combustion Analysis in Compression-Ignited Advanced Concepts

2018 ◽  
Vol 8 (10) ◽  
pp. 1707 ◽  
Author(s):  
José Serrano ◽  
Ricardo Novella ◽  
Josep Gomez-Soriano ◽  
Pablo Martinez-Hernandiz
Keyword(s):  
Cfd Simulation ◽  
Initial Conditions ◽  
Three Dimensional ◽  
Pressure Rise ◽  
Navier Stokes ◽  
Maximum Pressure ◽  
Engine Operation ◽  
Partially Premixed Combustion ◽  
Rise Rate ◽  
Operation Results

In the present work, a numerical methodology based on three-dimensional (3D) computational fluid dynamics (CFD) was developed to predict knock in a 2-Stroke engine operating with gasoline Partially Premixed Combustion (PPC) concept. Single-cycle Unsteady Reynolds-Averaged Navier Stokes (URANS) simulations using the renormalization group (RNG) k − ε model were performed in parallel while the initial conditions are accordingly perturbed in order to imitate the variability in the in-cylinder conditions due to engine operation. Results showed a good agreement between experiment and CFD simulation with respect to cycle-averaged and deviation of the ignition timing, combustion phasing, peak pressure magnitude and location. Moreover, the numerical method was also demonstrated to be capable of predicting knock features, such as maximum pressure rise rate and knock intensity, with good accuracy. Finally, the CFD solution allowed to give more insight about in-cylinder processes that lead to the knocking combustion and its subsequent effects.

Characterization of Partially Premixed Combustion With Ethanol: EGR Sweeps, Low and Maximum Loads

2010 ◽  
Vol 132 (8) ◽  
Author(s):  
Vittorio Manente ◽  
Bengt Johansson ◽  
Pert Tunestal
Keyword(s):  
High Efficiency ◽  
Pressure Rise ◽  
Premixed Combustion ◽  
Maximum Pressure ◽  
Pressure Rise Rate ◽  
Start Of Injection ◽  
Partially Premixed Combustion ◽  
Rise Rate ◽  
Partially Premixed ◽  
Gas Recirculation

Exhaust gas recirculation (EGR) sweeps were performed on ethanol partially premixed combustion (PPC) to show different emission and efficiency trends as compared with diesel PPC. The sweeps showed that when the EGR rate is increased, the efficiency does not diminish, HC trace is flat, and CO is low even with 45% of EGR. NOx exponentially decreases by increasing EGR while soot levels are nearly zero throughout the sweep. The EGR sweeps underlined that at high EGR levels, the pressure rise rate is a concern. To overcome this problem and keep high efficiency and low emissions, a sweep in the timing of the pilot injection and pilot-main ratio was done at ∼16.5 bars gross IMEP. It was found that with a pilot-main ratio of 50:50, and by placing the pilot at −60 with 42% of EGR, NOx and soot are below EURO VI levels; the indicated efficiency is 47% and the maximum pressure rise rate is below 10 bar/CAD. Low load conditions were examined as well. It was found that by placing the start of injection at −35 top dead center, the efficiency is maximized, on the other hand, when the injection is at −25, the emissions are minimized, and the efficiency is only 1.64% lower than its optimum value. The idle test also showed that a certain amount of EGR is needed in order to minimize the pressure rise rate.

Characterization of Partially Premixed Combustion With Ethanol: EGR Sweeps, Low and Maximum Loads

2009 ◽  
Author(s):  
Vittorio Manente ◽  
Bengt Johansson ◽  
Pert Tunestal
Keyword(s):  
High Efficiency ◽  
Pressure Rise ◽  
Premixed Combustion ◽  
Maximum Pressure ◽  
Pressure Rise Rate ◽  
Partially Premixed Combustion ◽  
Rise Rate ◽  
Low Load ◽  
Partially Premixed

EGR sweeps were performed on Ethanol Partially Premixed Combustion, PPC, to show different emission and efficiency trends as compared to Diesel PPC. The sweeps showed that increasing the EGR rate the efficiency does not diminish, HC trace is flat and CO is low even with 45% of EGR. NOx exponentially decreases by increasing EGR while soot levels are nearly zero throughout the sweep. The EGR sweeps underlined that at high EGR levels, the pressure rise rate is a concern. To overcome this problem and keep high efficiency and low emissions a sweep in timing of the pilot injection and pilot-main ratio was done at ∼16.5 bar gross IMEP. It was found that with a pilot-main ratio of 50–50 and by placing the pilot at −60 with 42% of EGR, NOx and soot are below EURO VI levels, the indicated efficiency is 47% and the maximum pressure rise rate is below 10 bar/CAD. Low load conditions were examined as well. It was found that by placing the SOI at −35 TDC the efficiency is maximized on the other hand when the injection is at −25 the emissions are minimized and the efficiency is only 1.64% lower than its optimum value. The idle test also showed that a certain amount of EGR is needed in order to minimize the pressure rise rate.

Vibration analysis and combustion parameter evaluation of CI engine based on Fourier Decomposition Method

2021 ◽  
pp. 146808742098819
Author(s):  
Wang Yang ◽  
Cheng Yong
Keyword(s):  
Vibration Analysis ◽  
Decomposition Method ◽  
Combustion Process ◽  
Pressure Rise ◽  
Maximum Pressure ◽  
Vibration Signals ◽  
Loop Control ◽  
Fourier Decomposition ◽  
Surface Vibration ◽  
Rise Rate

As a non-intrusive method for engine working condition detection, the engine surface vibration contains rich information about the combustion process and has great potential for the closed-loop control of engines. However, the measured engine surface vibration signals are usually induced by combustion as well as non-combustion excitations and are difficult to be utilized directly. To evaluate some combustion parameters from engine surface vibration, the tests were carried out on a single-cylinder diesel engine and a new method called Fourier Decomposition Method (FDM) was used to extract combustion induced vibration. Simulated and test results verified the ability of the FDM for engine vibration analysis. Based on the extracted vibration signals, the methods for identifying start of combustion, location of maximum pressure rise rate, and location of peak pressure were proposed. The cycle-by-cycle analysis of the results show that the parameters identified based on vibration and in-cylinder pressure have the similar trends, and it suggests that the proposed FDM-based methods can be used for extracting combustion induced vibrations and identifying the combustion parameters.

Performance of Dual Fuel Engine Running on Jojoba Oil as Pilot Fuel and CNG or LPG

2007 ◽  
Author(s):  
Mohamed Y. E. Selim ◽  
M. S. Radwan ◽  
H. E. Saleh
Keyword(s):  
Methyl Ester ◽  
Natural Gas ◽  
Pressure Rise ◽  
Combustion Noise ◽  
Dual Fuel ◽  
Maximum Pressure ◽  
Injection Timing ◽  
Pressure Rise Rate ◽  
Rise Rate ◽  
Pilot Fuel

The use of Jojoba Methyl Ester as a pilot fuel was investigated for almost the first time as a way to improve the performance of dual fuel engine running on natural gas or LPG at part load. The dual fuel engine used was Ricardo E6 variable compression diesel engine and it used either compressed natural gas (CNG) or liquefied petroleum gas (LPG) as the main fuel and Jojoba Methyl Ester as a pilot fuel. Diesel fuel was used as a reference fuel for the dual fuel engine results. During the experimental tests, the following have been measured: engine efficiency in terms of specific fuel consumption, brake power output, combustion noise in terms of maximum pressure rise rate and maximum pressure, exhaust emissions in terms of carbon monoxide and hydrocarbons, knocking limits in terms of maximum torque at onset of knocking, and cyclic data of 100 engine cycle in terms of maximum pressure and its pressure rise rate. The tests examined the following engine parameters: gaseous fuel type, engine speed and load, pilot fuel injection timing, pilot fuel mass and compression ratio. Results showed that using the Jojoba fuel with its improved properties has improved the dual fuel engine performance, reduced the combustion noise, extended knocking limits and reduced the cyclic variability of the combustion.

Computational Characterization of Passive Fluid Mixing in Microfluidics

Volume 3 ◽  
2004 ◽  
Author(s):  
Erik D. Svensson
Keyword(s):  
Stokes Equations ◽  
Initial Conditions ◽  
Three Dimensional ◽  
Fluid Mixing ◽  
Navier Stokes ◽  
Navier Stokes Equations ◽  
Fluid Systems ◽  
Sensitive Dependence ◽  
Microfluidic Mixers

In this work we computationally characterize fluid mixing in a number of passive microfluidic mixers. Generally, in order to systematically study and characterize mixing in realistic fluid systems we (1) compute the fluid flow in the systems by solving the stationary three-dimensional Navier-Stokes equations or Stokes equations with a finite element method, and (2) compute various measures indicating the degree of mixing based on concepts from dynamical systems theory, i.e., the sensitive dependence on initial conditions and mixing variance.

scholarly journals PARALLEL COMPUTATIONS IN STUDIES OF DEPENDENCE OF GAS DYNAMIC PARAMETERS OF UPWARD SWIRLING FLOW OF GAS ON BLOWING VELOCITY

2016 ◽  
pp. 92-97
Author(s):  
R. E. Volkov ◽  
A. G. Obukhov
Keyword(s):  
Stokes Equations ◽  
Swirling Flow ◽  
Initial Conditions ◽  
Exact Analytical Solution ◽  
Three Dimensional ◽  
Navier Stokes ◽  
Heat Conducting ◽  
Computational Domain ◽  
Navier Stokes Equations ◽  
Gas Dynamic

The rectangular parallelepiped explicit difference schemes for the numerical solution of the complete built system of Navier-Stokes equations. These solutions describe the three-dimensional flow of a compressible viscous heat-conducting gas in a rising swirling flows, provided the forces of gravity and Coriolis. This assumes constancy of the coefficient of viscosity and thermal conductivity. The initial conditions are the features that are the exact analytical solution of the complete Navier-Stokes equations. Propose specific boundary conditions under which the upward flow of gas is modeled by blowing through the square hole in the upper surface of the computational domain. A variant of parallelization algorithm for calculating gas dynamic and energy characteristics. The results of calculations of gasdynamic parameters dependency on the speed of the vertical blowing by the time the flow of a steady state flow.

scholarly journals The Numerical Diffusion Effect on the CFD Simulation Accuracy of Velocity and Temperature Field for the Application of Sustainable Architecture Methodology

2020 ◽  
Vol 12 (23) ◽  
pp. 10173
Author(s):  
Vladimíra Michalcová ◽  
Kamila Kotrasová
Keyword(s):  
Temperature Field ◽  
Cfd Simulation ◽  
Flow Direction ◽  
Three Dimensional ◽  
Stationary Flow ◽  
Navier Stokes ◽  
Ansys Fluent ◽  
Simulation Accuracy ◽  
Numerical Diffusion ◽  
Diffusion Temperature

Numerical simulation of fluid flow and heat or mass transfer phenomenon requires numerical solution of Navier–Stokes and energy-conservation equations, together with the continuity equation. The basic problem of solving general transport equations by the Finite Volume Method (FVM) is the exact calculation of the transport quantity. Numerical or false diffusion is a phenomenon of inserting errors in calculations that threaten the accuracy of the computational solution. The paper compares the physical accuracy of the calculation in the Computational Fluid Dynamics (CFD) code in Ansys Fluent using the offered discretization calculation schemes, methods of solving the gradients of the transport quantity on the cell walls, and the influence of the mesh type. The paper offers possibilities on how to reduce numerical errors. In the calculation area, the sharp boundary of two areas with different temperatures is created in the flow direction. The three-dimensional (3D) stationary flow of the fictitious gas is simulated using FVM so that only advective transfer, in terms of momentum and heat, arises. The subject of the study is to determine the level of numerical diffusion (temperature field scattering) and to evaluate the values of the transport quantity (temperature), which are outside the range of specified boundary conditions at variously set calculation parameters.

scholarly journals A Numerical Investigation on De-NOx Technology and Abnormal Combustion Control for a Hydrogen Engine with EGR System

Processes ◽  
2020 ◽  
Vol 8 (9) ◽  
pp. 1178
Author(s):  
Hao Guo ◽  
Song Zhou ◽  
Jiaxuan Zou ◽  
Majed Shreka
Keyword(s):  
Hot Spots ◽  
Three Dimensional ◽  
Pressure Rise ◽  
Nox Emissions ◽  
Combustion Duration ◽  
Rise Rate ◽  
Peak Heat Release Rate ◽  
Combustion Emissions ◽  
Computational Fluid Dynamics Cfd ◽  
Gas Recirculation

The combustion emissions of the hydrogen-fueled engines are very clean, but the problems of abnormal combustion and high NOx emissions limit their applications. Nowadays hydrogen engines use exhaust gas recirculation (EGR) technology to control the intensity of premixed combustion and reduce the NOx emissions. This study aims at improving the abnormal combustion and decreasing the NOx emissions of the hydrogen engine by applying a three-dimensional (3D) computational fluid dynamics (CFD) model of a single-cylinder hydrogen-fueled engine equipped with an EGR system. The results indicated that peak in-cylinder pressure continuously increased with the increase of the ignition advance angle and was closer to the top dead center (TDC). In addition, the mixture was burned violently near the theoretical air–fuel ratio, and the combustion duration was shortened. Moreover, the NOx emissions, the average pressure, and the in-cylinder temperature decreased as the EGR ratio increased. Furthermore, increasing the EGR ratio led to an increase in the combustion duration and a decrease in the peak heat release rate. EGR system could delay the spontaneous combustion reaction of the end-gas and reduce the probability of knocking. The pressure rise rate was controlled and the in-cylinder hot spots were reduced by the EGR system, which could suppress the occurrence of the pre-ignition in the hydrogen engine.

Numerical Flow Analysis in a Subsonic Vaned Radial Diffuser With Leading Edge Redesign

1999 ◽  
Vol 121 (1) ◽  
pp. 119-126 ◽  
Author(s):  
E. Casartelli ◽  
A. P. Saxer ◽  
G. Gyarmathy
Keyword(s):  
Static Pressure ◽  
Flow Analysis ◽  
Three Dimensional ◽  
Pressure Rise ◽  
Leading Edge ◽  
Inverse Design ◽  
Navier Stokes ◽  
Two Dimensional ◽  
Characteristic Lines ◽  
Design Software

The flow field in a subsonic vaned radial diffuser of a single-stage centrifugal compressor is numerically investigated using a three-dimensional Navier–Stokes solver (TASCflow) and a two-dimensional analysis and inverse-design software package (MISES). The vane geometry is modified in the leading edge area (two-dimensional blade shaping) using MISES, without changing the diffuser throughflow characteristics. An analysis of the two-dimensional and three-dimensional effects of two redesigns on the flow in each of the diffuser subcomponents is performed in terms of static pressure recovery, total pressure loss production, and secondary flow reduction. The computed characteristic lines are compared with measurements, which confirm the improvement obtained by the leading edge redesign in terms of increased pressure rise and operating range.

Using the Maximum Pressure Principle for Verification of Calculation of Stationary Subsonic Flow

2019 ◽  
pp. 4-16
Author(s):  
V.A. Anikin ◽  
V.V. Vyshinsky ◽  
O.A. Pashkov ◽  
E.V. Streltsov
Keyword(s):  
Computer Technology ◽  
Stokes System ◽  
Subsonic Flow ◽  
Three Dimensional ◽  
Ideal Gas ◽  
Navier Stokes ◽  
Maximum Pressure ◽  
Flow Parameters ◽  
Criteria For Evaluation ◽  
Principle Of Maximum

The principle of maximum pressure for subsonic stationary three-dimensional vortex flows of an ideal gas (author Sizykh G.B., 2018) is applied to verify the calculation method and its implementation on a specific computer technology. The four criteria for solution's verification are proposed. The method for obtaining flow parameters is based on solving of discrete analogs of the Navier --- Stokes system of equations on three-dimensional non-structured computational meshes. For example, there was consider the vortex tear-off flow around the fuselage of a helicopter with an empennage and landing gear at obviously insufficient computing resources. Conclusions of the feasibility of applying the author's criteria for evaluation of a particular calculation and for estimation of reliability of the results have been made.

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