scholarly journals Effect of Valve Opening Manner and Sealing Method on the Steady Injection Characteristic of Gas Fuel Injector

Energies ◽  
2020 ◽  
Vol 13 (6) ◽  
pp. 1479
Author(s):  
Tianbo Wang ◽  
Lanchun Zhang ◽  
Qian Chen
Keyword(s):  
Steady State ◽  
Three Dimensional ◽  
Injection Pressure ◽  
Operating Conditions ◽  
Fuel Injector ◽  
Injection Efficiency ◽  
Mixing Performance ◽  
Cfd Models ◽  
Valve Opening ◽  
Gas Fuel

The steady-state injection characteristic of gas fuel injector is one of the key factors that affects the performance of gas fuel engine. The influences of different injection strategies, such as different injection angles and different injection positions, on the mixing performance in gas-fueled engine have been emphasized in previous literatures. However, the research on the injection characteristics of the gas fuel injector itself are insufficient. The three-dimensional steady-state computational fluid dynamics (CFD) models of two kinds of injectors, in different opening manners, and the other two kinds of injectors, in different sealing methods, were established in this paper. The core region speed, stagnation pressure loss and mass flow rate were compared. Additionally, the effective injection pressure (EIP) concept was also used to evaluate the injection efficiency of gas fuel injector. The simulation results show that the jet speed of the pull-open injector is higher than the push-open injector under the same operating conditions. The injection efficiency of the pull-open valve is about 56.0%, while the push-open valve is 50.3%. In general, the steady-flow characteristic of the pull-open injector is better than that of the push-open one. The injection efficiency of the flat sealing injector is 55.2%, slightly lower than the conical sealing method.

Transient Analysis of a Ceramic High Temperature Heat Exchanger and Chemical Decomposer

2007 ◽  
Author(s):  
Valery Ponyavin ◽  
Taha Mohamed ◽  
Mohamed Trabia ◽  
Yitung Chen ◽  
Anthony E. Hechanova
Keyword(s):  
Steady State ◽  
High Temperature ◽  
Heat Exchanger ◽  
Thermal Stresses ◽  
Three Dimensional ◽  
Failure Criteria ◽  
Operating Conditions ◽  
Finite Element Software ◽  
Micro Channels ◽  
Temperature Heat

Ceramics are suitable for use in high temperature applications as well as corrosive environment. These characteristics were the reason behind selection silicone carbide for a high temperature heat exchanger and chemical decomposer, which is a part of the Sulphur-Iodine (SI) thermo-chemical cycle. The heat exchanger is expected to operate in the range of 950°C. The proposed design is manufactured using fused ceramic layers that allow creation of micro-channels with dimensions below one millimeter. A proper design of the heat exchanges requires considering possibilities of failure due to stresses under both steady state and transient conditions. Temperature gradients within the heat exchanger ceramic components induce thermal stresses that dominate other stresses. A three-dimensional computational model is developed to investigate the fluid flow, heat transfer and stresses in the decomposer. Temperature distribution in the solid is imported to finite element software and used with pressure loads for stress analysis. The stress results are used to calculate probability of failure based on Weibull failure criteria. Earlier analysis showed that stress results at steady state operating conditions are satisfactory. The focus of this paper is to consider stresses that are induced during transient scenarios. In particular, the cases of startup and shutdown of the heat exchanger are considered. The paper presents an evaluation of the stresses in these two cases.

scholarly journals Experimental investigation energy balance and distribution of a turbocharged GDI engine fuelled with ethanol and gasoline blend under transient and steady-state operating conditions

2020 ◽  
Vol 24 (1 Part A) ◽  
pp. 243-257 ◽  
Author(s):  
Xiongbo Duan ◽  
Yiqun Liu ◽  
Xianjie Zhou ◽  
Peng Zou ◽  
Jingping Liu
Keyword(s):  
Experimental Investigation ◽  
Steady State ◽  
Thermal Efficiency ◽  
Cfd Simulation ◽  
Design Procedure ◽  
Operating Conditions ◽  
Fuel Injector ◽  
Gdi Engine ◽  
Rotating Injector ◽  
Transient And Steady State

Improving the performance and reducing emissions in a Diesel engine is the single most objective in current research. Various methods of approach have been studied and presented in literature. A novel but not so pursued study is on the performance of a rotating diesel injector. To date, there has been very little study by implementing a rotating injector. Studies have shown an improvement on the performance of an engine, but with a complicated external rotating mechanism. In the present research, a novel self-rotating fuel injector is designed and developed that is expected to improve the performance without the need for a complicated rotating mechanism. The design procedure, CFD simulation along with 3- D printing of a prototype is presented. Numerical modelling and simulation are performed to study the combustion characteristics of the rotating injector viz-a-viz a standard static injector. Comparison based on heat release, efficiency, and emissions are presented. While the proposed 9-hole injector had slight loss in thermal efficiency, the modified 5-hole had a slight increase in thermal efficiency when compared to the static baseline readings. The NOx reduced by 13% and CO increased by 14% compared baseline emissions for the 5-hole version.

scholarly journals Three-dimensional imaging of swirled spray injection in a generic aero engine burner under realistic operating conditions

2021 ◽  
Vol 63 (1) ◽  
Author(s):  
Joachim Klinner ◽  
Christian E. Willert
Keyword(s):  
High Speed ◽  
Cross Correlation ◽  
Droplet Diameter ◽  
Three Dimensional ◽  
Operating Conditions ◽  
Field Analysis ◽  
Calibration Data ◽  
Engine Fuel ◽  
Fuel Injector ◽  
Aero Engine

AbstractTomographic shadowgraph imaging is applied to reconstruct the instantaneous three-dimensional spray field immediately downstream of a generic aero engine fuel injector. Within the swirl passage of the injector model, a single kerosene jet undergoes air-blast atomization in a cross-flow configuration at Weber numbers of $$\text {We}=360-770$$ We = 360 - 770 , air pressures of $$p_a=4-7\,\text{ bar }$$ p a = 4 - 7 bar and air temperatures of $$T_a=440-570\,\text{ K }$$ T a = 440 - 570 K . High-speed, high magnification shadowgraphy is used to visualize the initial fuel atomization stages within the fuel injector before the spray enters the spray chamber. The 4-camera tomographic measurement setup is described in detail and includes a depth-of-field analysis with respect to droplet size based on Mie simulations and calibration data of the point-spread function. For a volume size of $$16\times 13\times 10\,\text{ mm}^3$$ 16 × 13 × 10 mm 3 , the smallest resolvable droplet diameter is estimated to be $$d=10\,\mu \text{ m }$$ d = 10 μ m within the focal plane and increases to $$d \approx 20\,\mu \text{ m }$$ d ≈ 20 μ m toward the edges of the volume. Droplet velocities above the resolution limit were retrieved by 3-d cross-correlation of two volumetric reconstructions recorded at two consecutive time-steps. This is accompanied by an error analysis on the random error dependency on the camera viewing geometry. The results indicate increasing motion and fluctuations of the spray tail with increasing temperature and Weber number. Validation against PDA data further downstream of the burner plate revealed consistency for size classes $$d=10\,\mu \text{ m }$$ d = 10 μ m and $$d=15\,\mu \text{ m }$$ d = 15 μ m . Deviations from PDA occur in regions with strong velocity gradients due to different spatial resolutions, the presence of reconstruction ambiguities (ghost particles), uncertainties inherent to the two-frame cross-correlation of spray volumes and the finite LED pulse duration. Graphical Abstract

scholarly journals Reducing the Life Cycle Cost of Swing Check Valves

1996 ◽  
Author(s):  
O. Roorda ◽  
J. D. McNeill ◽  
M. Wright
Keyword(s):  
Life Cycle ◽  
Steady State ◽  
Pressure Loss ◽  
Life Cycle Cost ◽  
Check Valve ◽  
Operating Conditions ◽  
Opening Angle ◽  
Flow Profile ◽  
Seal Design ◽  
Valve Opening

Within the oil and gas industry there is an emerging trend to estimate expenses for pipelines and system components using a Life Cycle Cost (LCC) basis. This paper describes a new sizing model for swing check valves that can assist in significantly reducing the LCC of the valve. The incremental fuel cost of the compressor arising from pressure loss across the valve is the largest component of the valve’s LCC. The valve’s pressure loss can be minimized by correct valve sizing ensuring full valve opening under normal flow conditions. This new sizing program, applied to an NPS 20 natural gas pipeline, can result in cost savings in the order of two times the capital cost of a swing check valve when compared to traditional sizing methods. The pressure loss across the valve is primarily determined by the opening angle of the valve disc during steady state operation. A steady state valve model was developed and formed the basis for a sizing program for swing check valves. The sizing program assists in optimizing the valve for specified operating conditions. Within margins, the valve opening characteristic can be optimized by adjusting the valve sizing parameters such as valve size, disc weight, counter balance mass and position for a specified set of operating conditions. The LCC of a swing check valve can be further reduced by up to 45% through optimization of the valve design. The sizing program was used in a parametric study to assess the areas relevant in the design optimization of the valve. To further reduce the LCC of swing check valves, research should focus on improving the internal flow profile of the valve, reducing disc weight and eliminating the need for counter balance weights through improving low friction seal design.

Study of Steady State and Transient Blade Row CFD Methods in a Moderately Loaded NASA Transonic High-Speed Axial Compressor Stage

2013 ◽  
Author(s):  
Mohammed Abdullah Qizar ◽  
Mahmoud L. Mansour ◽  
Shraman Goswami
Keyword(s):  
Steady State ◽  
High Speed ◽  
Transient Flow ◽  
Three Dimensional ◽  
Operating Conditions ◽  
Computational Time ◽  
Laser Doppler Velocimeter ◽  
Compressor Stage ◽  
Steady Stage ◽  
Blade Row

The effect of blade row interaction and hub leakage flow on the performance of moderately loaded NASA transonic hybrid compressor stage (Rotor 35 / Stator 37) is investigated through three-dimensional steady state and time-accurate, Navier Stokes calculations of the stage using the ANSYS CFX code at peak efficiency and near stall operating conditions. Understanding unsteady flow phenomena in compressor stages requires the use of time-accurate CFD simulations. Due to the inherent differences in blade counts between adjacent blade rows, the flow conditions at any given instant in adjacent blade rows differ. Depending on the blade counts, it may be necessary to model the entire annulus of the stage; however, this requires considerable computational time and memory resources. Several methods for modeling the transient flow in turbo machinery stages which require a minimal number of blade passages per row, and therefore reduced computational demands, have been presented in the literature. Recently, some of these methods have become available in commercial CFD solvers. The paper describes the steady and the unsteady CFD approaches used for investigating the ability to predict the measured performance of the NASA transonic axial stage design known as the hybrid stage, which consists of the axial Rotor35 and the axial stator 37. The steady approach employs the mixing-plane while the unsteady approaches are URANS with one based on full annulus simulation for the stage and the second enables simulations for the stage using reduced computational model, with a single passage from each blade row based on the time-tilting or the time-transformation technique. The above methods are evaluated and compared in terms of computational efficiency and comparison is made to steady stage simulations. Comparisons to overall performance data and two-dimensional Laser Doppler Velocimeter measurements of the velocity field are used to assess the predictive capabilities of the methods. Computed flow features are examined, and compared with reported measurements. This paper presents validation and calibration of methods used for determining blade row interactions and the respective predictive capabilities against the full annulus and the experimental test data.

Comparative thermal stress analysis of gasketed and non-gasketed flange joints for safe operating conditions

2009 ◽  
Vol 223 (3) ◽  
pp. 167-178 ◽  
Author(s):  
M Abid ◽  
M Iqbal ◽  
B Ullah
Keyword(s):  
Steady State ◽  
Internal Pressure ◽  
Thermal Loading ◽  
Complex Analysis ◽  
Load Capacity ◽  
Experimental Studies ◽  
Three Dimensional ◽  
Operating Conditions ◽  
Element Analysis ◽  
Safe Operating

The performance of a flanged joint is characterized mainly by its ‘strength’ and ‘sealing capability’. A number of analytical and experimental studies have been conducted to study these characteristics under only internal pressure loading. However, with the advent of new technological trends for high temperature and high-pressure applications, an increased demand for more complex analysis is recognized. The effect of steady-state thermal loading is a well-recognized problem and makes the analysis more complex. To investigate joint strength and sealing capability under combined internal pressure and different steady-state thermal loadings, a comparative three-dimensional non-linear finite-element analysis of gasketed and non-gasketed flange joints is carried out and their behaviour is discussed. To determine the safe operating conditions or actual joint load capacity, both the flange joints are further analysed for different internal pressures and temperatures.

The Influence of Valve Port Design on the Volumetric Efficiency of the Compression-Ignition Engine

1948 ◽  
Vol 2 (1) ◽  
pp. 63-79
Author(s):  
C B. Dicksee
Keyword(s):  
Combustion Engine ◽  
Operating Conditions ◽  
Volumetric Efficiency ◽  
Valve Lift ◽  
Essential Difference ◽  
Compression Ignition ◽  
Fuel Injector ◽  
Compression Ignition Engine ◽  
Port Design ◽  
Valve Opening

In the paper the author discusses the cause of the loss of pressure in the induction system of an internal combustion engine, and also the essential difference between the breathing conditions of a carburetting engine and those of a compression-ignition engine, and the features which are peculiar to the latter. He gives particulars of some experiments on the influence of valve ports of different shapes upon the breathing of a given compression-ignition engine cylinder. The experiments cover the measurement of the pressure loss under a steady air flow as well as the effect upon the volumetric efficiency under actual operating conditions. The effect of a change in valve lift is discussed also. The results of the experiments show that the governing factor in volumetric efficiency is the velocity of the air at the actual valve opening, and that a Venturi form of port provides much needed room for the accommodation of the fuel injector, without any sacrifice in volumetric efficiency, by allowing a material reduction in diameter of the port at a short distance ahead of the valve opening. It does not, however, possess any other great advantage over a parallel port with an equal diameter of valve seat.

A CFD Simulation Analysis of the Water Volumetric Fraction Distribution in the Runner of a Turgo Type Turbine Designed With an Integrated Dimensional Methodology

2014 ◽  
Author(s):  
Jorge Luis Clarembaux Correa ◽  
Jesús de Andrade ◽  
Sergio Croquer ◽  
Miguel Asuaje
Keyword(s):  
Steady State ◽  
Cfd Simulation ◽  
Simulation Analysis ◽  
Three Dimensional ◽  
Flow Distribution ◽  
Steady State Regime ◽  
Volumetric Fraction ◽  
Cfd Models ◽  
Fraction Distribution ◽  
State Regime

Our previous work, on development of a design methodology inspired in the analysis of One-Dimensional and Three-dimensional Theories [1], allowed to obtain a Turgo Type Turbine (TTT) bucket using 8 geometric parameters as a function of the jet diameter, and Rankine Ovoids potential flow. CFD models under steady state regime [2] made possible to verify deduced expressions for torque, output power and hydraulic efficiency. In this paper, the effects of the water volumetric fraction distribution in the runner have been included, which are significantly conclusive to understand the runner hydrodynamic behavior and highlighted several optimizations to the performance equations that could be considered as a potential novelty for these turbines. In the same way, an influence study of nozzle parameters determined that the most profitable performance is achieved for an absolute velocity angle coming from the jet of 19.8°. Finally, several differences in the flow distribution in the runner were evaluated through a non-steady state regime CFD simulation, when comparing with the steady state.

Use of CFD Modeling for Designing Intake and Discharge Structures in a Discharge Canal

2010 ◽  
Author(s):  
Fangbiao Lin ◽  
George Pigg ◽  
Gerald Schohl
Keyword(s):  
Power Plants ◽  
Cooling Tower ◽  
Three Dimensional ◽  
Operating Conditions ◽  
Cfd Modeling ◽  
The North ◽  
Cfd Models ◽  
Discharge Canal ◽  
Before And After ◽  
Pros And Cons

This paper presents a computational fluid dynamics (CFD) modeling approach for designing intake and discharge structures in a discharge canal for nuclear and fossil power plants. It discusses how the CFD models are developed, what types of results can be obtained from the CFD modeling study and how the results are used for developing designs of the intake and discharge structures. The pros and cons of the CFD modeling method for this type of application are also discussed. Intake and discharge structures for a “Helper Cooling Tower South” will be added to the discharge canal of the Crystal River Energy Complex (CREC). The CFD modeling was used to confirm suitable locations for the new intake and discharge structures to minimize potential recirculation and potential loss of cooling tower efficiency, and to evaluate the erosion of the banks on the north and south side of the canal due to the flow from the discharge structure. The CFD model was developed using FLUENT for the existing and future configurations of the discharge canal that consists of the existing intake, discharges, and the new intake and discharge structures. The CFD modeling runs were performed to investigate three-dimensional flow patterns, velocities and temperatures in the discharge canal under current and future operating conditions. Current and future conditions refer to those before and after installation of the Helper Cooling Tower South Intake and Discharge structures, respectively. Comparing the CFD results (streamlines, temperature and velocity distributions, etc.) for the future conditions to those for the existing conditions, the locations and designs of the new intake and discharge structures were assessed and developed. This study demonstrates that the new intake is not impacted by the new and existing discharge structures, and the existing intake will perform similarly as it performs before the construction of the new intake and discharges. The study also identifies some sections of the canal banks and bottom that may need to be protected from erosion due to the impacts of the high velocity water from the discharge structures.

scholarly journals A quantitative analysis of nozzle surface bound fuel for diesel injectors

2017 ◽  
Author(s):  
Jack Turner ◽  
Dan Sykes ◽  
Guillaume De Sercey ◽  
Viacheslav Stetsyuk ◽  
Martin Gold ◽  
...  
Keyword(s):  
Pressure Drop ◽  
High Speed ◽  
Injection Pressure ◽  
Spreading Rate ◽  
Operating Conditions ◽  
Fuel Injector ◽  
Surface Wetting ◽  
Long Distance ◽  
Coverage Area ◽  
Fluid Behaviour

In a fuel injector at the end of the injection, the needle descent and the rapid pressure drop in the nozzle leads todischarge of large, slow-moving liquid structures. This unwanted discharge is often referred as fuel ‘dribble’ and results in near-nozzle surface wetting, creating fuel-rich regions that are believed to contribute to unburnt hydrocarbon emissions. Subsequent fluid overspill occurs during the pressure drop in the expansion stroke when residual fluid inside the nozzle is displaced by the expansion of trapped gases as the pressure through the orifices is equalised, leading to further surface wetting. There have been several recent advancements in the characterisation of these near nozzle fluid processes, yet there is a lack of quantitative data relating the operating conditions and hardware parameters to the quantity of overspill and surface-bound fuel. In this study, methods for quantifying nozzle tip wetting after the end of injection were developed, to gain a better understanding of the underlying processes and to study the influence of engine operating conditions. A high-speed camera with a long- distance microscope was used to visualise fluid behaviour at the microscopic scale during, and after, the end of injection. In order to measure the nozzle tip temperature, a production injector was used which was instrumented with a type K thermocouple near one of the orifices. Image post-processing techniques were developed to track both the initial fuel coverage area on the nozzle surface, as well as the temporal evolution and spreading rate of surface-bound fluid. The conclusion presents an analysis of the area of fuel coverage and the rate of spreading and how these depend on injection pressure, in-cylinder pressure and in-cylinder temperature. It was observed that for this VCO injector, the rate of spreading correlates with the initial area of fuel coverage measured after the end of injection, suggesting that the main mechanism for nozzle wetting is through the impingement of dribble onto the nozzle. However, occasional observations of the expansion of orifice-trapped gas were made that lead to asignificant increase in nozzle wetting.DOI: http://dx.doi.org/10.4995/ILASS2017.2017.4661

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