Prediction and evolution of drop-size distribution of an ultrasonic vibrating microchannel

This paper was presented at the 2nd Micro and Nano Flows Conference (MNF2009), which was held at Brunel University, West London, UK. The conference was organised by Brunel University and supported by the Institution of Mechanical Engineers, IPEM, the Italian Union of Thermofluid dynamics, the Process Intensification Network, HEXAG - the Heat Exchange Action Group and the Institute of Mathematics and its Applications.We report in this paper the evolution of a physically-based drop size-distribution coupling the Maximum Entropy Formalism and the Monte Carlo method to solve the distribution equation of a spray. The atomization is performed by a new Spray On Demand (SOD) device which exploits ultrasonic generation via a Faraday instability. The Modified Hamilton’s principle is used to describe the fluid structure/interaction with a vibrating micro-channel conveying fluid excited by a pointwise piezoactuator. We combine to the fluid/structure description a physically based approach for predicting the drop-size distribution within the framework of the Maximum Entropy Formalism (MEF) using conservation laws of energy and mass coupling with the three-parameter generalized Gamma distribution. The prediction and experimental validation of the drop size distribution of a new Spray On Demand print-head is performed. The dynamic model is shown to be sensitive to operating conditions, design parameter and physico-chemical properties of the fluid and its prediction capability is good. We also report on a model allowing the evolution of drop sizedistribution. Deriving the discrete and continuous population balance equation, the Mass Flow Algorithm is formulated taking into account interactions between droplets via coalescence. After proposing a kernel for coalescence, we solve the time dependent drop size distribution using a Monte Carlo Method which is shown to be convergent. The drops size distribution upon time shows the effect of spray droplets coalescence

Experimental verification of computer spray-combustion models

Analytical model formulation, representing performance of spray-combustion device, is based on understanding of atomization, mixing, vaporization, and combustion which occurs in device. Report lists results of correlations of computed values with values obtained from experiments with rocket combustor. Technique offers excellent method for evaluating validity and ranges of applicability of combustion models

SPRAY DRYING INVESTIGATIONS ON MEDICINAL PLANT BASED PHARMACEUTICAL PRODUCTS

In the paper we report about spray drying investigations on medicinal herb extracts. We investigated the production technologies of up-to-date pharmaceutical products and natural raw materials of drugs. In this paper we report in detail about spray drying investigation of some medicinal plants and about how to define the operational features of these products. In our tests we could find that the extract of camomile, rose hip and lime blossom can be processed well by spray drying. We worked out the main operational features to be applied when using spray drying under industrial circumstances

Design and Development of an Airblast Atomiser for the KAVERI engine and the sectoral combustor tests

This report deals with the design and development of an airblast atomiser for application in the KAVERI engine. Five atomisers of the chosen design were fabricated and tested at ambient conditions to determine the fuel spray SMD, patternation, cone angle and atomiser flow number. The atomiser performance parameters specified were achieved and hot tests carried out in the 90° combustor sector. The combustor pressure loss, exit temperature distribution, ignition and stability limits were evaluate

Salzgitter Report

Report about spray nozzles, page 2https://digitalcommons.wpi.edu/ms077morgan-docs/1149/thumbnail.jp

Correlation of spray dropsize distribution and injector variables Interim report

Correlation of spray drop size distribution and injector variable

A review of the ONR/NAVAIR research option combustion instabilities in compact ramjets, 1983-1988

This paper consists of two parts summarizing two portions of the ONR/NAVAIR Research Option. The option began in 1983 and continued for five years, involving 11 organizations. Simultaneously, similar or related programs supported by other agencies or institutions were being carried out in several other places. Results of those programs have been briefly summarized in five papers collected in a document to be published by C.P.L.A. This paper contains two of the five papers in that document. Here we cover the subjects of approximate analyses and stability; and large-scale structures and passive control. The first is concerned chiefly with an analytical framework constructed on the basis of observations; it is intended to provide a means of correlating and interpreting data, and predicting the stability of motions in a combustion chamber. The second is a summary of recent experimental work directed to understanding the flows in dump combustors of the sort used in modern ramjet engines. Much relevant material is not included here, but may be found in the remaining papers of the document cited above. For completeness, we note briefly the substance of those reports. In their summary "Spray Combustion Processes in Ramjet Combustion Instability," Bowman (Stanford), Law (University of California, Davis) and Sirignano (University of California, Irvine) review several aspects of spray combustion relevant to combustion instabilities. The objectives of the works were: (1) to determine the effect of spray characteristics on the energy release pattern in a dump combustor and the subsequent effects on combustion instability; (2) to gain a fundamental understanding of the coupling of the spray vaporization process with an unsteady flow field; and (3) to investigate methods for controlling and enhancing spray vaporization rates in liquid-fueled ramjets. During the past five years considerable progress has been made in applying methods of computational fluid dynamics to the flow in a dump combustor including consequences of energy release due to combustion processes. Jou has summarized work done at Flow Research, Inc. and at the Naval Research Laboratory in his paper "A Summary Report on Large-Eddy Simulations of Pressure Oscillations in a Ramjet Combustor." The serious effects of combustion instabilities on the inlets of ramjet engines were discovered in the late 1970's in experimental work at the Aeropropulsion Laboratory, Wright Field, the Naval Weapons Center and the Marquardt Company. The most thorough laboratory work on the unsteady behavior of inlets has been accomplished at the McDonnell-Douglas Research Laboratory by Sajben who has reviewed the subject in his paper "The Role of Inlet in Ramjet Pressure Oscillations.

To grate a liquid into tiny droplets by its impact on a hydrophobic micro-grid

We report on experiments of drop impacting a hydrophobic micro-grid, of typical spacing a few tens of $\mu$m. Above a threshold in impact speed, liquid emerges to the other side, forming micro-droplets of size about that of the grid holes. We propose a method to produce either a mono-disperse spray or a single tiny droplet of volume as small as a few picoliters corresponding to a volume division of the liquid drop by a factor of up to 10$^5$. We also discuss the discrepancy of the measured thresholds with that predicted by a balance between inertia and capillarity.Comment: 3 pages, 5 figures, Accepted for publication in Applied Physics Letter

MOUDI analysis of particle size distributions for ultrasonic spraying of salt solutions from an array of microscopic orifices

We report characterization of spray-based nanoporous particle synthesis for use in the cathode of lithium-ion batteries. Ultrasonic Microarray Spray Tuning (uMIST) was used to create microdroplets of salt solutions and battery material precursors, and the size distributions of produced microdroplets were investigated with a MicroOrifice Uniform Deposit Impactor (MOUDI). Experimental challenges associated with spray orientation, flow control and consistency of operation were addressed, and a promising solution for continuous droplet collection to obtain a statistically relevant droplet size distribution was proposed. Improved analysis capabilities will lead to a better understanding of the uMIST droplet formation mechanism