Plasma assisted combustion: Dynamics and chemistry

http://engine.princeton.edu/Publications/Ombrello_2010-2.pdf

Flame propagation enhancement by plasma excitation of oxygen. Part I: Effects of O3

conferencia sobre "Particle Image Velocimetry" de les 13:00-14:00 a la Sala de Juntes de l'FNB impartida pel professor Peter Bueken da l'Antwerp Maritime Acedemy (Belgica)

Particle Image Velocimetry

A review of livestock monitoring and the need for integrated systems

This paper presents a method aimed at recognizing environmental sounds for surveillance and security applications. We propose to apply one-class support vector machines (1-SVMs) together with a sophisticated dissimilarity measure in order to address audio classification, and more specifically, sound recognition. We illustrate the performance of this method on an audio database, which consists of 1015 sounds belonging to nine classes. The database used presents high intraclass diversity in temps of signal properties and some kind of interclass similarities. A large discrepancy in the number of items in each class implies nonuniform probability of sound appearances. The method proceeds as follows: first, the use of a set of state-of-the-art audio features is studied. Then, we introduce a set of novel features obtained by combining elementary features. Experiments conducted on a nine-class classification problem show the superiority of this novel sound recognition method. The best recognition accuracy (96.89%) is obtained when combining wavelet-based features, MFCCs, and individual temporal and frequency features. Our 1-SVM-based multiclass classification approach overperforms the conventional hidden Markov model-based system in the experiments conducted, the improvement in the error rate can reach 50%. Besides, we provide empirical results showing that the single-class SVM outperforms a combination of binary SVMs. Additional experiments demonstrate our method is robust to environmental noise.

Using One-Class SVMs and Wavelets for Audio Surveillance

A premixing injector for use in gas turbine engines assists in the lean premixed injection of a gaseous fuel/air mixture into the combustor of a gas turbine. The premixing injector is designed to mix fuel and air at high velocities to eliminate the occurrence of flashback of the combustion flame from the reaction zone into the premixing injector. The premixing injector includes choked gas ports, which allow the fuel supply to be decoupled from any type of combustion instability which may arise in the combustor of the gas turbine and internal passages to provide regenerative cooling to the device.

Premixing injector for gas turbine engines

In ground test applications for simulated embedded engine systems, it is often necessary to forego direct-connect inlet/engine configurations and simulate inlet produced distortion profiles. Classically, this has been accomplished through the use of wire-mesh screens layered over a thick supporting grid. Other traditional approaches of distortion generation rely on active controls and/or empirical loss models for various geometries (such as airfoils, cylinders, and screens). These widely tabulated loss models limit the design of such device elements to those available in the literature. The freedom provided by advanced manufacturing methods would significantly expand the design space for such an application, giving rise to complex geometries that are not commercially available or feasible to manufacture. Therefore, an accurate distortion model relating total pressure losses to any geometry is necessary for a true design optimization of the distortion generator. This paper presents such a model by relating total pressure losses to various system interactions in classical fluid dynamic relationships. The total pressure loss models are formulated for incompressible and compressible flow conditions, where the total pressure across the screen is manipulated by either a mass exchange or adjusting the drag characteristics of the screen. This model is fully derived for the case of incompressible flow with drag, and validated against experimental data collected from a low-speed wind tunnel test. The accurate prediction of the reduced-order model with the low-speed results gives rise to a higher fidelity “continuous” screen in which every cell is tailored for a specific total pressure value.

Improved Prediction Method for the Design of High-Resolution Total Pressure Distortion Screens

Engine/airframe integration in advanced aircraft concepts must account for nonuniform flows ingested by turbofan engines. In this work, flow details from a vane-based distortion generator were anal...

StreamVane Turbofan Inlet Swirl Distortion Generator: Mean Flow and Turbulence Structure

Preheating of fuel and injection into a plasma torch plume fro adjacent the plasma torch plume provides for only ignition with reduced delay but improved fuel-air mixing and fuel atomization as well as combustion reaction enhancement. Heat exchange also reduced erosion of the anode of the plasma torch. Fuel mixing atomization, fuel mixture distribution enhancement and combustion reaction enhancement are improved by unsteady plasma torch energization, integral formation of the heat exchanger, fuel injection nozzle and plasma torch anode in a more compact, low-profile arrangement which is not intrusive on a highspeed air flow with which the invention is particularly effective and further enhanced by use of nitrogen as a feedstock material and inclusion of high pressure gases in the fuel to cause effervescence during injection.

/pdf/improved-plasma-torch-for-ignition-flameholding-and-5878dx4xrh.pdf

Improved Plasma Torch for Ignition, Flameholding and Enhancement of Combustion in High Speed Flows

Loss models used in compression system performance prediction codes are often developed from the study of two-dimensional cascades. In this paper, compressible fluid mechanics has been applied to the changes in shock geometry that are known to occur with back pressure for unstarted operation of supersonic compressor cascades. This physics-based engineering shock loss model is applicable to cascades with arbitrary airfoil shapes. Predictions from the present method have been compared to measurements and Navier-Stokes analyses of the L030-4 and L030-6 cascades, and very good agreement was demonstrated for unstarted operation. A clear improvement has been demonstrated over previously published shock loss models for unstarted operation, both in the accuracy of the predictions and in the range of applicability. The dramatic increase in overall loss with increasing inlet flow angle is shown to be primarily the result of increased shock loss, and much of this increase is caused by the detached bow shock. For a given Mach number, the viscous profile loss is nearly constant over the entire unstarted operating range of the cascade, unless a shock-induced boundary layer separation occurs near stall. Shock loss is much more sensitive to inlet Mach number than is viscous profile loss.

Walter F. O'Brien

Papers

Premixing injector for gas turbine engines

Improved Prediction Method for the Design of High-Resolution Total Pressure Distortion Screens

StreamVane Turbofan Inlet Swirl Distortion Generator: Mean Flow and Turbulence Structure

Improved Plasma Torch for Ignition, Flameholding and Enhancement of Combustion in High Speed Flows

A shock loss model for supersonic compressor cascades