Colin R. Ferguson

Stand-off distances on a flat flame burner

Abstract For a given stand-off distance of a laminar flame on a porous metal burner, it has been shown both experimentally and theoretically that there exists two solutions, a low-speed flame and a high-speed flame. For small enough stand-off distance there is no solution. The minimum stand-off distance is identified as the quasi-steady approximation to the extinction length for flames quenching in flows perpendicular to a heat sink. Measurements of flame speed, maximum flame temperature, and stand-off distance have been correlated for hydrogen, ethylene, and methane flames by a Peclet number dependent only on the ratio of the heat of combustion to the heat loss. The correlation agrees quantitatively with solution of one-dimensional flame equations where a Dirac-delta function models the reaction rate.

Unburned gas temperatures in an internal combustion engine. I: Cars temperature measurements

Abstract Broadband,coherent anti-Stokes Raman scattering (CARS) measurements of unburned gas temperatures have been performed in an internal combustion engine.The engine is fueled with n-butane and air and is operated under both knocking and non-knocking conditons.Temperatures are determined by fitting calculated CARS spectra to experimentally obtained,cycle-averaged nitrogen CARS spectra.The accuracy of the fitted temperature depends on a number of factors,including the modeling of collisional narrowing and the response of the intensified diode array detector,the accuracy of nitrogen linewidths and nonresonant susceptibilities used in the CARS fitting code,and the use of the correct laser line shape convolution.The estimated accuracy of the CARS temperatures is 5-9 percent and is presently limited by long-term drift in the broadband dye laser frequency spectrum.The CARS temperatures are compared with the temperature predictions of a heat release model for the engine.The implications of the measurements f...

Mass spectrometry/mass spectrometry: capabilities and applications to fuel-related materials

Abstract The expanding capabilities of mass spectrometry/mass spectrometry (m.s.-m.s.) in mixture analysis and its applications to fuel-related materials are illustrated. High and low collision energy m.s.-m.s. data obtained on reverse geometry and triple quadrupole spectrometers are given for coal-derived liquid (SRC II) and diesel particulate samples. The direct analysis capability of the m.s.-m.s. methodology and its limitations are illustrated for the identification of an aliphatic carboxylic acid in diesel paniculate. The selective ionization techniques of ammonia chemical ionization and negative chemical ionization are shown to be particularly useful in enhancing the specificity of m.s.-m.s. characterizations. Negative chemical ionization is used to confirm the presence of hydroxybenzoic acid in a diesel particulate sample. Combined laser desorption-chemical ionization is also demonstrated to be an effective ionization technique in m.s.-m.s. analysis. A variant of m.s.-m.s., in which selected anions fragment with charge inversion to give fragment cations, is also employed in the analysis of SRC II and used to identify thioaryl moieties. Functional group screening by an alternative m.s.—m.s. scan procedure, neutral loss scanning, is demonstrated for phenols in SRC II. A scan for all parent ions of a selected daughter ion provides a screening procedure for rapidly identifying all compounds of a given structural type in a complex mixture. The dependence of m.s.-m.s. spectra on collision energy and pressure is shown to add further detail to m.s.—m.s. analysis. The development of a library of m.s.—m.s. spectra of reference compounds to be used for the identification of individual constituents in fuel-related materials is described.

A diesel combustion bomb: proof of concept

A combustion bomb has been developed which allows simulation of diesel combustion without the need to heat the bomb to high temperatures. Simulation of the compression stroke is achieved by burning a lean precharge composed of acetylene, oxygen and nitrogen. By controlling the initial partial pressures of these constituents it is possible to burn them to a state with an oxygen concentration, temperature and pressure representative of conditions in a diesel engine at the start of fuel injection. Diesel fuel injected into these gases autoignites and burns in a manner typical of combustion in diesel engines. 22 references, 24 figures.

Multidimensional Modeling of Radiative Heat Transfer in Diesel Engines

This paper illustrates use of the first and the third order spherical harmonics approximation to the radiative transfer equation and the delta-Eddington approximation to the scattering phase function for droplets in the flow. Solutions are presented for an axisymmetric, finite cylindrical geometry and assumed distributions for temperature, soot and fuel droplets chosen to be representative of conditions in a diesel engine during combustion. Results are obtained numerically by an accurate finite difference scheme. Important goals of this paper are to investigate the importance of scattering by fuel droplets and of accounting for spatial variations in the extinction coefficient on the radiative flux distributions at the walls of a disc shaped diesel engine. 21 references, 16 figures.

Bunsen flame hydrodynamics

Abstract An investigation into the structure of premixed Bunsen flames was performed to determine whether by using laser velocimetry an unambiguous means of measuring laminar flame speed could be devised and to provide data by which theoreticians could critically evaluate their predictions. Data presented for the former include the axisymmetric flow field and a comparison of cone angles obtained from direct and schlieren photographs of the flame. Data presented for the latter include, for varying equivalence ratios and cone angles, the radius of curvature of the tip and change in velocity through the tip. The centerline velocity was found to decay as a function of axial distance, and a noncoincidence of schlieren and luminous surfaces was observed. When normalized by a preheat thickness (based on the harmonic mean of the thermal conductivity), the behavior of the radius of curvature of the tip compared well with a recent theoretical prediction.

Hot‐wire pyrometry

A hot‐wire pyrometer for measuring gas temperatures with a high sensitivity has been developed. The method can easily be extended to measurements of surface temperature. The principal elements of a hot‐wire pyrometer are a fine wire inserted into the gas and a photomultiplier for measuring the radiation emitted from it. The output voltage V of the photomultiplier is shown both theoretically and experimentally to be the following function of wire temperature T: V=σT7/4 exp(−γT−1/2), where σ and γ are the calibration constants unique to a particular system.

A fuel injection transducer and controller

A fuel injection meter and controller has been developed which (1) measures the instantaneous injection rate and the total mass of fuel injected, and (2) controls the mass of fuel injected and injection pressure. The injection rate is computed from instantaneous measurements of the velocity of a pumping plunger and the pressure of fuel injection. A mathematical model of the meter and controller was developed to further the understanding of various design and operating parameters on the injection rate. Compressibility of the fuel is accounted for. Good agreement is realized between numerically computed injection pressure and rate histories with corresponding experimental results.

Characterization of Diesel Particulates by Mass Spectrometry Including MS-MS

Particles have been collected from a direct injection diesel engine at varying dilution ratios and air temperatures for four different operating conditions. Particle samples have been introduced into a mass spectrometer ion source with a direct insertion probe thus dispensing with the extraction processes typically used in chemical characterization. The sample is volatized and then chemically ionized using isobutane. Typical mass spectra are presented for each operating condition. The samples analyzed have a mean molecular weight of 195 amu with a standard deviation of approximately 100 amu. Application of tandem mass spectrometry for species identification is illustrated. Both negative and positive chemical ionization are employed to identify carboxylic acids in the particulate. Several types of ms-ms scans are shown to have utility in this study, including scans which provide molecular weight profiles for compounds having common functional groups. This latter methodology is shown to be a particularly rapid and sensitive procedure for following changes in emission characteristics in response to altered engine conditions.

The effect of aspect ratio on heat loss from a swirling flow within a cylinder

Abstract Measurements have been made of the total rate of heat loss and the half radius swirl velocity of an unsteady, turbulent swirling flow within a cylinder for different aspect ratios. The instantaneous heat loss correlates with the half radius swirl velocity by a Nusselt-Reynolds number power law. The correlation is independent of aspect ratio if the filling of the cylinder results in a flow field which is axi-symmetric and shows no axial variation outside the boundary layers.