Russel Lockett

Exa-flo Ltd · Engineering

A purely experimental technique was employed to derive temperatures from nitrogen Q-branch Coherent Anti-Stokes Raman Scattering (CARS) spectra, obtained in a high pressure, high temperature environment (spark ignition Otto engine). This was in order to obviate any errors arising from deficiencies in the spectral scaling laws which are commonly use...

Dynamical systems analysis was employed as an alternative investigative tool to conventional reaction path analysis and sensitivity analysis in methanol-air auto-ignition, in which the non-linear chemical rate equations describing a homogeneous, methanol-air auto-ignition system were linearised. The resultant system of linear, inhomogeneous differe...

A sample of unadditized diesel fuel was passed through an optically accessible model diesel injector return valve, which consisted of two successive nozzles connected to an intermediate fuel gallery. The first nozzle was cylindrical, while the second nozzle was stepped. The fuel was observed to produce a multi-phase, cavitating flow and a luminous...

Samples of unadditized, middle distillate diesel fuel were injected through real-size optically accessible mini-sac diesel injectors into ambient air at common rail pressures of 250 bar and 350 bar respectively. High-resolution images of white light scattered from the internal mini-sac and nozzle flow were captured on a high-speed monochrome video...

Modern high-pressure Diesel fuel injection equipment (FIE) employ fuel recirculation through sequential nozzles located inside fuel injectors to control the pressure, flow rate and amount of fuel injected into the engine. Common rail accumulator pressure is often controlled through relief valves that return excess fuel back to the fuel tank. Dies...

Modern high-pressure Diesel fuel injection equipment (FIE) employ fuel recirculation through sequential nozzles located inside fuel injectors to control the pressure, flow rate and amount of fuel injected into the engine. Common rail accumulator pressure is often controlled through relief valves that return excess fuel back to the fuel tank. Diesel...

A sample of middle distillate, unadditized diesel fuel was passed through an optically accessible, fused silica model diesel injector return valve with an upstream and downstream pressure of 240 bar and ambient respectively. The fused silica model return valve consisted of two successive nozzles connected to an intermediate fuel gallery. The first...

Samples of unadditized, middle distillate diesel fuel were injected through a real-size optically accessible mini-sac diesel injector into ambient air at common rail pressures of 250 bar and 350 bar respectively, employing a customised diesel fuel injection system. Images of white light scattered from the internal mini-sac and nozzle flow were capt...

In modern magnetic solenoid actuated diesel injection equipment, the injection cycle process is regulated by the action of the ball spill valve. This connects the high-pressure region of the needle valve and the low-pressure region of the fuel tank. The precision in timing and hydrodynamic forces determines the amount injected and the amount of the...

Modern high-pressure diesel fuel injection equipment (FIE) meter the diesel fuel supply to the injectors and engine from one or more of the high-pressure pump, the pressure accumulator (common rail), and the injectors. The fuel metering process requires the separated fuel to be returned back to the fuel tank via control valves. The relaxation flow...

The determination of the distribution of the local liquid volume fraction (LVF) in non-evaporating diesel sprays was achieved using Lase Induced Fluorescence (LIF). The LVF distribution developing during the primary and secondary atomisation was investigated as a function of rail pressure, physical properties and needle lift. Samples of conventiona...

Most modern high-pressure common rail diesel fuel injection systems employ an internal pressure equalization system in order to provide the force necessary to support needle lift, enabling precise control of the injected fuel mass. This results in the return of a substantial proportion of the high-pressure diesel back to the fuel tank. The diesel f...

High-speed planar laser Mie scattering and Laser Induced Fluorescence (PLIF) was employed for the determination of Sauter Mean Diameter (SMD) distribution in non-evaporating diesel sprays. The effect of rail pressure, distillation profile, and consequent fuel viscosity on the drop size distribution developing during primary and secondary atomizatio...

Cavitation inception occurring in immersed jets was investigated in a purpose-built mechanical flow rig. The rig utilized custom-built cylindrical and conical nozzles to direct high-velocity jets of variable concentration n-octane-hexadecane mixtures into a fused silica optically accessible receiver. The fluid pressure upstream and down-stream of t...

A conventional diesel and paraffinic-rich model diesel fuel were subjected to sustained cavitation in a custom-built high-pressure recirculation flow rig. Changes to the spectral extinction coefficient at 405 nm were measured using a simple optical arrangement. The spectral extinction coefficient at 405 nm for the conventional diesel sample was obs...

High speed video shadowgraph and Schlieren images of spherical explosion flames obtained in the Leeds bomb have been analysed in the context of the Bechtold-Matalon linear model of spherical explosion flame instabilities. Analysis of the dispersion relation identifies the peninsula of instability, and the conditions for which the spherical explosio...

High speed video shadowgraph and Schlieren images of spherical explosion flames obtained in the Leeds bomb have been analysed in the context of the Bechtold-Matalon linear model of spherical explosion flame instabilities. Analysis of the dispersion relation identifies the peninsula of instability, and the conditions for which the spherical explosio...

Samples of commercial diesel were subjected to forty hours of intense cavitation flow across a diesel injector in a specially designed high-pressure recirculation flow rig. In the high pressure part of the rig, diesel samples were compressed to 550 bar using a continuous flow high pressure pump. In the low pressure part of the rig, the diesel sampl...

Two identical, conventional six-hole, valve-covered orifice (VCO) diesel injectors have been modified in order to provide optical access to the region below the needle, and the nozzle-flow passages. This has been achieved through the removal of the metal tips, and their replacement with transparent acrylic tips of identical geometry. These two iden...

Planar laser induced fluorescence (PLIF) was employed in a three sector, low NOx double annular combustor in order to characterise the combusting fuel spray. Naphthalene was em-ployed as a fluorescent agent in odourless kerosene in order to determine the behavior of the light fractions in the fuel vapour, and the light to medium fractions in the fu...

Laser sheet drop-sizing (LSD) measurements of a Diesel spray and simultaneous laser induced incandescence/Mie scattering measurements of soot have been performed in an optically accessible, common rail, 1.9 litre, turbo-charged, direct injection Diesel engine. The diesel fuel injectors employed in this study were prototype five hole injectors, supp...

A conventional six-hole valve-covered orifice (VCO) injector nozzle has been modified in order to provide optical access to the region below the needle, and the nozzle passages. This has been achieved through the removal of the metal tip, and its replacement with a transparent acrylic tip of identical geometry. Elastic scattering of light obtained...

Flame instabilities, cellular structures and soot formed in high pressure, rich, spherically expanding iso-octane-air flames have been studied experimentally using high speed Schlieren cinematography, OH fluorescence, and laser induced incandescence. Cellular structures with two wavelength ranges developed on the flame surface. In rich flames with...

Flame instabilities, cellular structures and soot formed in high pressure, rich, spherically expanding iso-octane-air flames have been studied experimentally using high speed Schlieren cinematography, OH fluorescence, and laser induced incandescence. Cellular structures with two wavelength ranges developed on the flame surface. In rich flames with...

Simultaneous OH planar laser-induced fluorescence (PLIF) and Rayleigh scattering measurements have been performed on 2-bar rich iso-octane–air explosion flames obtained in the optically accessible Leeds combustion bomb. Separate shadowgraph high-speed video images have been obtained from explosion flames under similar mixture conditions. Shadowgrap...

The spray characteristics of a prototype piezo pintle-type injector are investigated in a single-cylinder optical direct injection spark ignition (DISI) engine based on the spray-guided concept where mixture preparation is dominated by the spray dynamics. The high-pressure piezo electric injector has an annular nozzle providing a hollow cone spray....

Flame instabilities, cellular structures and soot formed in high pressure, rich, spherically expanding iso-octane-air flames have been studied experimentally using high speed Schlieren cinematography, OH fluorescence, Mie scattering and laser induced incandescence. Cellular structures with two wavelength ranges developed on the flame surface. The l...

The Planar Laser Induced Fluorescence (PLIF) technique was used to characterise the fuel concentration distribution inside a single-cylinder direct-injection gasoline optical engine, in terms of two-dimensional, instantaneous and high-resolution images. The research engine employs a 4-valve pent-roof cylinder head, with the optical access obtained...

Premixed iso-octane and methane-air flames have been ignited in a fan stirred bomb in laminar conditions and turbulent flow fields at 1 and 5 bar. Sheet images of the flames were captured using LIF of OH. In spherically expanding laminar flames, the shape of cusps in the flame surface was shown to change from a dent for flames with positive Markste...

The purpose of this study was to identify whether the so-called “triple-flame” actually exists in the ignition of turbulent mixing layers. We have designed and constructed a novel partially premixed co-flow burner utilising laser ignition to produce freely propagating flame kernels in a turbulent mixing layer. The flow has been characterised with H...

Flame instabilities and the formation of cellular structures during spherical gaseous explosions have been studied experimentally using natural light and schlieren high-speed cine photography, as well as single-shot planar laser-induced fluorescence (PLIF) from the OH radical. High-pressure, rich-hydrocarbon and lean-hydrogen flames at low Markstei...

The flame stability map defining the regime of existence of a counter-flowing laminar partially premixed methane-air “triple flame” has been determined using OH Planar Laser Induced Fluorescence (PLIF). The stability limits were determined through the observation of flame merging and flame extinction, a function of rich and lean equivalence ratios,...

A diesel spray has been characterised in terms of relative drop size distribution, relative number density and relative liquid volume fraction using combined planar laser induced fluorescence and laser sheet dropsizing.

Combined planar Mie scattering and laser induced fluorescence (LIF) obtained from a spray seeded with a fluorescent agent permits droplet sizing, and is termed Laser Sheet Dropsizing or LSD [1]. This technique has enabled the characterisation of the spray in terms of the relative drop size distribution, the relative drop number density, and the rel...

Introduction operating optically accessible diesel engine. Cranfield University was responsible for the whole of Target 1.3 and Step 1.4.2 of Target 1.4 for the Sprays Package section of Project Zodiac. The ultimate aim of the Sprays Package was to develop a quantitative diesel spray diagnostic. In this, most of the Steps specified in the program w...

Experimental observations of triple flame structure in rich partially premixed methane-air vs. lean premixed methane-air opposed-flow flames are analyzed numerically using detailed chemical kinetics and transport properties. The convenient counterflow configuration allows the system to be analyzed with a one-dimensional numerical treatment, avoidin...

Laser Induced Fluorescence (LIF) offers advantages over mechanical patternators and other laser diagnostics in providing high resolution instantaneous two-dimensional images of liquid and vapour fuel concentration in operating gas turbine combustors. The technique has been applied to an atmospheric pressure LPP combustor and a high pressure double...

This paper discusses the development of practical laser imaging diagnostics for applications to fundamental and practical combustion studies. The techniques discussed include: Laser Induced Fluorescence (LIF) for measurements of fuel; Laser Induced Incandescence (LII) for the estimation of soot volume fraction and combined with Mie soot particle si...

Radial and axial planar laser induced fluorescence (PILF) measurements of fuel distribution were obtained in a model low NOx double annular gas turbine combustor, using naphthalene and ppo as fuel markers for the mid fuel fractions (b.p ~ 220 deg C)and the heavy fuel fractions (b.p ~ 350 deg C). The different fuel fractions were observed to undergo...

Part of a project to investigate the physics and chemistry of alternative fuels in internal combustion engines is reported. Coherent anti-Stokes Raman spectroscopy (CARS) is used to probe the fuel-air mixture in the cylinder of a Richardo E6 variable compression ratio research engine. The laser system comprises a passively Q- switched single-longit...

We present a quantitative planar laser-induced fluorescence (PLIF) method for imaging the in-cylinderfuel concentration in a spark-ignition engine. The method is based on fluorescence from a carbonyl compound added to the fuel and excited by an excimer laser at 308 nm. The method has been applied to the study of charge stratification in a lean burn...

The temperature inside the cylinder of a methanol-fuelled and SASOL-fuelled single cylinder research engine running under knocking conditions is measured by means of coherent Anti-stokes Raman spectroscopy (CARS), and the pressure is measured with a piezoelectric transducer. In order to obviate any errors arising from possible deficiencies in the s...

In order to obviate any errors arising from deficiencies in the spectral scaling laws which are commonly used to represent nitrogen Q-branch spectra at high pressure, a purely experimental technique is employed to derive temperatures from a high pressure combustion environment from C.A.R.S. spectra, by cross-correlation with a reference library of...

The temperature inside the cylinder of a methanol-fuelled single cylinder Ricardo E6 research engine running under knocking conditions, is measured by means of Coherent Anti-Stokes Raman Spectroscopy (CARS), and the pressure is measured with a pressure transducer. In order to obviate any errors arising from deficiencies in the spectral scaling laws...

A set of combustion relevant rate coefficients recommended by a group of European kineticists has been tested by calculating laminar burning velocities. Virtually without any adjustments, a good match with experimental data has been achieved for H2/CO/air flames, H2/CO/air flames, and CH4/air flames. In order to extend this set by inclusion of the...

The temperature inside the cylinder of a methanol-fuelled single-cylinder research engine running under knocking conditions is measured by means of Coherent Anti-Stokes Raman Scattering (CARS) spectroscopy, and the pressure is measured with a piezoelectric transducer. In order to obviate any errors arising from possible deficiencies in the spectral...

A comprehensive combustion mechanism for methanol-air combustion was employed to model the auto-ignition occurring in a knocking, methanol fuelled spark ignition Ricardo E6 research engine. CARS temperature measurements and pressure profiles obtained during the compression stroke leading to auto-ignition were employed in the chemical kinetic auto-i...

CARS temperature measurements and pressure profiles have been obtained during the compression stroke in a knocking Ricardo E6 research engine, fuelled with methanol and SASOL gasoline fuels. The paper discusses the generation of the CARS signal, the analysis of the spectrum, and the temperature measurement methodology, in terms of the comparison of...

"Engine Knock" is investigated for methanol fuel, using experimentally obtained data for the compression process in a computational simulation of the end-gas spontaneous ignition process. The temperature of the end-gas was calculated from the experimentally obtained pressure using the perfect gas law and an empirical estimate for the heat loss from...

This thesis reports an investigation into the nature of electromagnetic vacuum polarization in the presence of an external field. The arguments presented link the formalism of quantum electrodynamics and classical electrostatics, in order to calculate the lowest order contribution to the photon self-energy, and then to calculate the charge distribu...

This paper reports an investigation into the nature of electromagnetic vacuum polarization in the presence of an external field. The arguments presented link the formalism of quantum electrodynamics and classical electrostatics, in order to calculate the lowest order contribution to the photon self-energy, and then to calculate the charge distribut...