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 Design and performance evaluation of a novel self-rotating fuel injector using computational fluid dynamics - a preliminary study

2020 ◽  
Vol 24 (1 Part A) ◽  
pp. 271-280
Author(s):  
Pichandi Chandrasekar ◽  
Neelakantan Prasad ◽  
Varadarajan Balamurugan ◽  
Natteri Sudharsan
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Performance Evaluation ◽  
Thermal Efficiency ◽  
Cfd Simulation ◽  
Design Procedure ◽  
Fuel Injector ◽  
Preliminary Study ◽  
And Performance ◽  
Rotating Injector

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 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 and Steady State Vibration Analysis of a Wavy Thrust Bearing

2005 ◽  
Vol 128 (1) ◽  
pp. 139-145 ◽  
Author(s):  
H. Zhao ◽  
F. K. Choy ◽  
M. J. Braun
Keyword(s):  
Steady State ◽  
Vibration Analysis ◽  
Thrust Bearing ◽  
Numerical Procedure ◽  
Operating Conditions ◽  
System Stability ◽  
Thrust Bearings ◽  
External Perturbations ◽  
Vibration Signature ◽  
Transient And Steady State

This paper describes a numerical procedure for analyzing the dynamics of transient and steady state vibrations in a wavy thrust bearing. The major effects of the wavy geometry and the operating parameters on the dynamic characteristics of the bearing had been discussed in a previous paper; the present paper thus concentrates on examining the relationships between the development of the transient and steady state vibrations when operating conditions are parametrically varied. Special attention is given to the development of steady state vibrations from initial transients with comparisons and consequences to the overall system stability. Numerical based vibration signature analysis procedures are then used to identify and quantify the transient vibrations. The conclusions provide general indicators for designing wavy thrust bearings that are less susceptible to transients induced by external perturbations.

Simulation of Mechanical Hydraulic System Dynamics Using Coupled Specialized Fluid Models and Multibody Dynamics

2015 ◽  
Author(s):  
Bradford Lynch
Keyword(s):  
Multibody Dynamics ◽  
Cfd Simulation ◽  
Experimental Testing ◽  
Operating Conditions ◽  
Injection System ◽  
Fluid Models ◽  
Hydraulic Systems ◽  
Fuel Injector ◽  
Advanced Technique ◽  
Prime Concern

Durability is a prime concern in the design of hydraulic systems and fuel injectors [1–3] thus an accurate prediction of impact velocities between components and the flow through them is essential to assessing concepts. Simulation of these systems is difficult because the geometries are complex, some volumes go to zero as the components move, and the flow at a single operating condition generally spans Reynolds numbers less than 1 to more than 104[4–8]. As a result of these challenges, experimental testing of prototypes is the dominant method for comparing concepts. This approach can be effective but is far more costly, time consuming, and less flexible than the ability to run simulations of concepts early in the design cycle. A validated model of a fuel injector built from publicly available data [1] is used to present a new approach to modelling hydraulic systems which overcomes many of these obstacles. This is accomplished by integrating several commercially available tools to solve the physics specific to each area within the fuel injector. First, the fuel injector is simulated using a 3D CFD simulation integrated with a 1D CFD system model. The flow in various regions of the injector is then analyzed to determine if the fluid models in these areas can be simplified based on the flow regime. Based on this analysis, a combination of models is assembled to improve the quality of the simulation while decreasing the time required to run the model. The fuel injector is simulated using a multibody dynamics model coupled to a reluctance network model of the solenoid and several fluid models. The first is a 3D CFD simulation which uses novel mesh refinement techniques during runtime to ensure high mesh quality throughout the motion of components, to resolve the velocity profile of laminar flows, and to satisfy the requirements of the RNG k-ε turbulence model and wall functions. This approach frees the analyst from defining the mesh before runtime and instead allows the mesh to adapt based on the flow conditions in the simulation. Due to the highly efficient meshing algorithm employed, it is possible to re-mesh at each timestep thus ensuring a high quality structured mesh throughout the simulation duration. Then a 3D FEM solution to the Reynolds Equation and a statistical contact model is employed to solve for the squeeze films between components and to allow separation and contact between bodies in the control valve. These detailed simulations are integrated with a 1D flow model of the fuel injection system. The results from the detailed coupled simulations are compared to the results from simpler 1D models and measured data to illustrate under which operating conditions a more advanced technique incorporating 3D CFD is worth the additional computational expense versus a traditional 1D model.

An Experimental Investigation of the Steady-State Response of a Noncontacting Flexibly Mounted Rotor Mechanical Face Seal

1995 ◽  
Vol 117 (1) ◽  
pp. 153-159 ◽  
Author(s):  
An Sung Lee ◽  
Itzhak Green
Keyword(s):  
Experimental Investigation ◽  
Steady State ◽  
Dynamic Behavior ◽  
Amplitude Ratio ◽  
Theoretical Work ◽  
Operating Conditions ◽  
Superior Performance ◽  
Steady State Response ◽  
State Response ◽  
Operation Conditions

Recent theoretical work on the dynamics of the noncontacting flexibly mounted rotor (FMR) seal has shown that it is superior in every aspect of dynamic behavior compared to the flexibly mounted stator (FMS) seal. The FMR seal is inherently stable regardless of the operating speed, the maximum relative misalignment response is smaller, and the critical stator misalignment is larger. All these are measures of superior performance. This work undertakes the experimental investigation of the dynamic behavior of a noncontacting FMR seal. The steady-state response of the FMR seal was measured at various operating conditions. The results are given in terms of dynamic and static transmissibilities, i.e., amplitude ratio of responses to two forcing inputs: the initial rotor and fixed stator misalignments. These are then compared to the analytical predictions. Further, operation maps are drawn for each set of operation conditions. The maps indicate how safely (away from contact) the seal operates. It is shown that the combination of the seal parameters that maximize the fluid film stiffness is optimal for safe noncontacting operation.

CFD Simulation of the CANDU-6 Moderator Circulation Under Normal Operating Conditions

2002 ◽  
Author(s):  
Bo Wook Rhee ◽  
Churl Yoon ◽  
Byung-Joo Min
Keyword(s):  
Steady State ◽  
Cfd Simulation ◽  
Volumetric Flow Rate ◽  
Operating Conditions ◽  
Maximum Temperature ◽  
Outlet Temperature ◽  
Frictional Pressure Drop ◽  
The Core ◽  
Hydraulic Impedance ◽  
Center Region

A steady-state 3D simulation for predicting the local subcooling of the moderator in the vicinity of the calandria tubes in a CANDU-6 reactor is performed. For the current simulation, a set of grid structures with the same geometry as the CANDU-6 moderator tank, called ‘calandria vessel’, is generated and the momentum, heat and continuity equations are solved by CFX-4.3, a CFD code developed by AEA technology. The standard k-ε turbulence model associated with logarithmic wall treatment is used to model turbulence generation and dissipation within the vessel. The moderator fluid is heavy water. Buoyancy forces are modeled using the Boussinesq approximation in which density is assumed to be a linear function of temperature. The matrix of the calandria tubes in the center region of the calandria vessel is simplified by the porous media approach. The anisotropic hydraulic impedance of the calandria tubes is modeled using the frictional pressure drop correlations suggested by Idelchik and Szymanski. The heat load in this steady-state simulation is conservatively set as 103 MW of 103% full power, consisting of 96.7 MW to the core region and 6.3 MW to the reflector region. The total volumetric flow rate through eight inlet nozzles is 940 L/s and the outlet temperature is constantly 71.0 °C. The thermal boundary condition of the circumferential vessel wall is assumed a little heat flux out. As a result, the velocity field and temperature distribution of a CANDU-6 moderator in the operating condition are presented. The flow pattern identified in this simulation is the weak jet momentum-dominated flow, which is generated by the interaction between the buoyancy force by heating and the dominant momentum forces by inlet jets. The calculated maximum temperature of the moderator is 83.0 °C at the lower center region of the core, which corresponds to the minimum subcooling of 33.0 °C considering the boiling point increase due to the hydrostatic pressure change.

Thermal Modeling of HRSG Transient Behavior in Combined Cycle Power Plants

2006 ◽  
Author(s):  
Sepehr Sanaye ◽  
Moein Rezazadeh ◽  
Jalaleddin Oladi ◽  
Gholam Hossein Sadeghpoor ◽  
Farid Bashiri ◽  
...  
Keyword(s):  
Steady State ◽  
Power Plants ◽  
Cold Start ◽  
Combined Cycle ◽  
Operating Conditions ◽  
Master Program ◽  
Load Change ◽  
Start Up ◽  
Program Software ◽  
Transient And Steady State

Combined Cycle Power Plants (CCPP) are attractive electricity generation systems due to high cycle efficiency and quick response of the system to load change. Heat recovery steam generator (HRSG) is an important part of a CCPP and it is important to predict the HRSG operating conditions in transient and steady state modes. It should be emphasized that the biggest pressure and thermal stresses are imposed on HRSG superheater and evaporator tubes banks during transient periods (cold start up and load change). Due to these effects a software program was developed for analyzing the HRSG transient and steady state operating conditions. The HRSG software included arbitrary number of pressure levels (usually up to three) and any number of elements (superheater, evaporator, economizer, desuperheater and duct burner). In this paper theories and equations (mass/energy balance and heat transfer coefficients) applied for HRSG thermal analysis are described. Also HRSG program software outputs were compared with real data collected from HRSG cold start-up at Tehran CCPP with specified geometry and arrangement of elements. The closeness of two groups of data in this transient and steady state modes was acceptable. The numerical outputs in steady state condition also were found very close to GT MASTER program software outputs.

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