Operation and Control of a Pulsejet with High Pressure Liquid Fuel Injection

Author(s):  
Andrew Naples ◽  
John Hoke ◽  
Daniel Paxson ◽  
Fred Schauer
Author(s):  
Chao Yong ◽  
Eric J. Barth

A high pressure combined air-fuel injection system is designed and tested for an experimental free liquid-piston engine compressor. The application discussed utilizes available high pressure air from the compressor’s reservoir, and high pressure fuel to mix and then inject into a combustion chamber. This paper addresses the modeling, design and control for this particular high-pressure air-fuel injection system, which features an electronically controlled air/fuel ratio control scheme. This system consists of a fuel line and an air line, whose mass flow rates are restricted by metering valves. These two lines are connected to a common downstream tube where air and fuel are mixed. By controlling the upstream pressures and the orifice areas of the metering valves, desired A/F ratios can be achieved. The effectiveness of the proposed system is demonstrated by a lumped-parameter model in simulation and validated by experiments.


Author(s):  
Y. Wang ◽  
L. Reh ◽  
D. Pennell ◽  
D. Winkler ◽  
K. Döbbeling

Stationary gas turbines for power generation are increasingly being equipped with low emission burners. By applying lean premixed combustion techniques for gaseous fuels both NOx and CO emissions can be reduced to extremely low levels (NOx emissions <25vppm, CO emissions <10vppm). Likewise, if analogous premix techniques can be applied to liquid fuels (diesel oil, Oil No.2, etc.) in gas-fired burners, similar low level emissions when burning oils are possible. For gas turbines which operate with liquid fuel or in dual fuel operation, VPL (Vaporised Premixed Lean)-combustion is essential for obtaining minimal NOx-emissions. An option is to vaporise the liquid fuel in a separate fuel vaporiser and subsequently supply the fuel vapour to the natural gas fuel injection system; this has not been investigated for gas turbine combustion in the past. This paper presents experimental results of atmospheric and high-pressure combustion tests using research premix burners running on vaporised liquid fuel. The following processes were investigated: • evaporation and partial decomposition of the liquid fuel (Oil No.2); • utilisation of low pressure exhaust gases to externally heat the high pressure fuel vaporiser; • operation of ABB premix-burners (EV burners) with vaporised Oil No.2; • combustion characteristics at pressures up to 25bar. Atmospheric VPL-combustion tests using Oil No.2 in ABB EV-burners under simulated gas turbine conditions have successfully produced emissions of NOx below 20vppm and of CO below 10vppm (corrected to 15% O2). 5vppm of these NOx values result from fuel bound nitrogen. Little dependence of these emissions on combustion pressure bas been observed. The techniques employed also ensured combustion with a stable non luminous (blue) flame during transition from gaseous to vaporised fuel. Additionally, no soot accumulation was detectable during combustion.


Author(s):  
Stefania Zanforlin ◽  
Roberto Gentili ◽  
Pierluigi Dell’Orto

Direct high-pressure liquid fuel injection is able to control the mixing process inside the cylinder for getting either stratified charge at partial loads or quasi-homogeneous conditions, as it is required at full load. This paper shows the development of this solution for small two-stoke engines, using multidimensional modelling. The aim is investigating how the design of scavenging ducts and combustion chamber influences charge stratification behaviour, taking into account fuel distribution and stratification stability varying engine load and speed.


Author(s):  
Dong-wei Wu ◽  
Bai-gang Sun ◽  
Dan Xu

Future diesel engines require the use of solenoid fuel injection system with the ultra-high pressure of more than 2000 bars. The nozzle, needle, and control plunger of the solenoid injector deform under high pressure. This deformation affects the movement characteristics of the needle, thereby influencing the precise control of fuel injection. A test rig is set up to investigate the structural deformation and influencing factors of the solenoid injector under high pressure. The structural deformation of nozzle, needle, and control plunger under different pressures can be obtained by measuring the displacement of the upper end of the control plunger in the axial direction. The experimental longitudinal deformation of nozzle, needle, and control plunger of the solenoid injector, which was selected for the study, reaches 0.109 mm under the pressure of 1600 bars. This value is close to 40% of the maximum needle lift, which is 0.3 mm. Thus, the deformation can no longer be ignored. In view of the solenoid injector deformation under high injection pressure, a three-dimensional calculation model is established. The calculated results are compared with the experimental data. The calculation total longitudinal deformation of nozzle, needle, control plunger, and contact surface reaches 0.238 mm under the pressure of 2500 bars. The structure deformation of solenoid injector with different materials or geometric parameters is calculated under the pressure of 100–2500 bars. The deformation with new materials is 0.198 mm and the deformation with new geometric parameters is 0.0333 mm under the pressure of 2500 bar. These calculations show that the use of shorter control plungers, shorter needles, and larger wall thickness nozzles can effectively reduce injector deformation under high pressure. The results of the study can provide guidance on injector design, which can work with high injection pressure and much accurate injection.


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