Henk Versteeg

Loughborough University | Lough · Wolfson School of Mechanical, Electrical and Manufacturing Engineering

We report the outcome of a European Pharmaceutical Aerosol Group study evaluating flow rate-rise times for reduced Next Generation Impactor (rNGI), Fast-Screening Impactor (FSI) and Fast-Screening Andersen impactor (FSA) with surrogate low-, medium- and high-resistance DPIs. Time for the flow rate to reach 90% of target (t90) and flow acceleration...

We present the results of a computer model of the transient flow behavior of abbreviated impactors (AIM) during testing of dry-powder inhalers. The principles of the model were established in a cross-industry study of full-resolution Next Generation Impactors (NGI) and Andersen impactors (ACI). Here, we apply the model to abbreviated impactors that...

Pressurized metered dose inhalers (pMDI) are one of the most common devices to deliver therapeutic treatment to patients with asthma or COPD. The atomization mechanism responsible for droplet production is poorly understood because of the short length and timescales involved, making experimental investigations to characterize fluid flow structures...

The Kigali amendment to Montreal protocol sets the timetable for phasing out of pMDI propellants HFA134a and HFA227ea, creating a requirement for green propellants to take their place. To assist this transition, accurate prediction of thermophysical properties that control aerosol generation of new formulations is crucial. A relevant challenge is h...

We describe a computational model that captures the physics of the unsteady air-flow startup that accompanies the testing of dry-powder inhalers (DPI) with cascade impactors (CIs) specifically when following methods described in the pharmacopeial compendia. This transient has been measured in a multi-organization study for a wide range of condition...

We report a cross-industry study characterizing flow rate-time profiles of equipment used for testing dry-powder inhalers (DPIs). Nine organizations used the same thermal mass flow sensor to record flow rate-time profiles at the inlet of individual participant compendial DPI test systems including either sample collection tubes (SCT), the Andersen...

A simple two-compartment, first-order flow resistance model of a cascade impactor reveals the reasons for the major trends observed in the companion, cross-industry study of the transient behavior of the inlet flow rate in compendial DPI test systems. This model is physically reasonable because most of the internal volume of compendial impactors is...

We report outcomes from an EPAG-led cross-industry study, characterizing flow rate/elapsed-time profiles of equipment used for testing dry powder inhalers (DPIs). A thermal mass flow sensor was used by nine organizations in a round-robin approach to record inlet flow rate-time profiles of individual participant compendial test systems (TS) includin...

A simple two-compartment, first-order flow resistance model of a cascade impactor reveals the reasons for the major trends observed in the companion, cross-industry study of the transient behaviour of the inlet flow rate in compendial DPI test systems. This model is physically reasonable because most of the internal volume of compendial impactors i...

The fine particle fraction is a key indicator of therapeutic effectiveness of inhaled pharmaceutical aerosols. This paper presents a fluorescence imaging technique to visualise and characterise the emission of active pharmaceutical ingredient (API) fines in model formulations containing coarse lactose carrier and 1.5-2 μm diameter fluorescent micro...

This paper presents an application of MRI to measure flow distribution in fuel cell channels. Solid Oxide Fuel Cells (SOFC) are able to efficiently produce electricity directly from the oxidation of the natural gas by electrochemical conversion. The distribution of fuel gas between the high numbers of parallel flow paths within the fuel cell assemb...

In this paper, droplet impact on a porous surface is experimentally investigated over a wide range of Weber numbers and surface temperatures. Regime transition criteria have been deduced to determine droplet post-impingement behaviour as a function of the Weber number and surface temperature for which a droplet impacting on a porous surface. Based...

This article reports the extension to binary propellant/excipient mixtures of the multiphase model of transient internal flow and atomization in pressurized metered dose inhalers (pMDIs) of Gavtash and colleagues for propellant-only flows. The work considers different accounts of the effect of less volatile ethanol on the saturated vapor pressure (...

The AIM Concept as an augmentation of full resolution cascade impactor (CI) measurements of the aerodynamic properties of aerosols emitted by OIPs has been in existence for about ten years. A previous EPAG-based survey undertaken five years ago indicated significant interest in the approach, particularly for the screening of candidate products in e...

Pressurised metered dose inhalers (pMDI) produce large numbers of droplets with size of smaller than 5 μm to treat asthma and other pulmonary diseases. The mechanism responsible for droplet generation from bulk propellant liquid is poorly understood, mainly because the small length scales and short time scales make it difficult to characterise tran...

Despite the popularity of the pMDI as an asthma remedy, the mechanism leading to spray generation is elusive, mainly due to small length scales and short time scale, causing experimental difficulties to obtain flow information. This mechanism involves transient development of two-phase flashing propellant flow inside pMDI actuator as well as transf...

The pressurised metered dose inhaler is one of the most popular devices for producing a respirable cloud of droplets or particles for inhaled therapy of respiratory conditions. The primary atomisation mechanism of a pMDI is relatively poorly understood. This work aims to further develop this fundamental understanding by conducting and analysing pha...

Addition of ethanol to propellant based formulations of pMDIs results in saturated vapour pressure alteration which is understood to have an impact on the droplet size of the resulting aerosol cloud 1, 2, 3, 4. Accurate and simple methods of estimating the saturated vapour pressure are important in developing the next generation of pMDI formulation...

The pressurised metered dose inhaler (pMDI) is the most widely used drug delivery system for asthma treatment. Over decades the pharmaceutical community has aimed to enhance system efficiency by paying particular attention to novel formulation development through experimentation. Fundamental understanding of the underlying physical phenomena that g...

Background: The dynamics of flow through the Andersen Cascade Impactor (ACI) at start-up for the performance evaluation of dry powder inhalers (DPIs) are poorly understood. Recent studies by the European Pharmaceutical Aerosols Group (EPAG) investigated the effects of reducing the sample volume on the aerodynamic particle size distributions (APSD)...

Effective drug delivery to the lungs by a DPI device requires the air-stream through the device to have sufficient power to aerosolise the powder. Furthermore, sufficient turbulence must be induced, along with particle-wall and particle–particle collisions, in order to de-aggregate small drug particles from large carrier particles. As a result, the...

The pressurised metered dose inhaler (pMDI) is the most widely prescribed device for asthma treatment and COPDs. The pMDI products of the industrial collaborators in this work (Chiesi Farmaceutici SpA) are solution formulations of HFA propellants and ethanol co-solvent to solubilise the active pharmaceutical ingredient. This paper reports the findi...

Sterile filtration is considered as a final step in processing pharmaceutical grade plasmid DNA. During the development of the filtration process, fundamental understanding on the mechanism of fouling is critical to improve filtration operations. The mechanism of fouling of pQR150 (20 kb) and pGEc47 (56 kb) plasmids DNA during constant pressure fil...

KEYWORDS: pressurized metered dose inhalers (pMDIs), metering valve, thermal properties, loss of prime, drainage

This paper presents experimentally measured data showing the impact of variable demand on a modern 800 MW CCGT plant. The results contrasting the performance of the plant when operating under optimum conditions with those measured when modulating the output to match dispatch instructions is presented and compared. These contrasts include the impact...

Pressurized metered-dose inhalers (pMDIs) have been the most effective therapeutic treatment for controlling lung diseases such as asthma and COPD. The flow through a two-orifice system of pMDI is very complex and poorly understood. Previous experimental work has shown that metastability may play a significant role in determining the flow condition...

In this work a new phenomenological model of growth of cartilage tissue cultured in a rotating bioreactor is developed. It represents an advancement of a previously derived model of deposition of glycosaminoglycan (GAG) in engineered cartilage by (i) introduction of physiological mechanisms of proteoglycan accumulation in the extracellular matrix (...

The purpose of this article is to review the different strategies for the delivery of plasmid DNA (pDNA)-based gene therapy. Plasmids are extrachromosomal DNA capable of being transmitted from cell to cell. They are supercoiled, circular covalently closed (ccc) strands of DNA capable of replication independently of host DNA and ranging from 5 to 40...

The thermodynamics and fluid mechanics of propellant flow in pressurised metered-dose inhalers (pMDIs) is complex and poorly understood. Previous work by Fletcher (1975) and Clark (1991) has shown that metastability may play a significant role in determining the flow conditions inside pMDIs. This paper presents a study of the thermodynamics and one...

As the industries are moving towards the alternatives to HCFC-22, more accurate and general calculation tools are required to predict the capillary tube performance using the new refrigerants. In the present paper, three different methods: Homogeneous Equilibrium Model (HEM), Delayed Equilibrium Model (DEM) and Improved Delayed Equilibrium Model (I...

Several details of the mechanism of gear lubrication are still in doubt in spite of many decades of study of this subject. The focus of our work is the investigation of the mechanism by which oil† temperature variations affect gear idle rattle, which requires an understanding of the distributions of lubricant and heat within a gearbox. This paper p...

Gear lubrication is of greater concern to the power transmission industry due to its lubricating and cooling functions. The study of fluid flow in gear lubrication is not only provides the crucial information to optimise the gear box design, but also allows interpretation of the mechanism of heat dissipation and power losses. We present results of...

Aerosol delivery of plasmid DNA therapeutic solutions is promising for the treatment of respiratory diseases. However, it poses challenges, most significantly the need to protect the delicate supercoiled (sc) structure of plasmid during aerosolization. Nebulizers for liquid aerosolization using meshes appear a better method for delivery than conven...

Pressurized metered dose inhalers (pMDIs) are the most widely prescribed and economical respiratory drug delivery systems. Conventional pMDI actuators-those based on "two-orifice-and-sump" designs-produce an aerosol with a reasonable respirable fraction, but with high aerosol velocity. The latter is responsible for high oropharyngeal deposition, an...

A wide variety of processes make use of plain orifice nozzles. Fuel injectors for internal combustion engines incorporate these nozzles to generate finely atomized sprays. Processes such as jet cutting, jet cleaning, and hydroentanglement, on the other hand, use similar nozzles, but require coherent jets. The spray or jet characteristics depend on...

The pressurised Metered Dose Inhaler (pMDI) has become the most prescribed drug delivery system for treating the respiratory diseases. However, the spray generation mechanism of these devices has not been extensively researched and there is very little information regarding the two-phase fluid dynamics associated with pre-atomisation inside the val...

A comprehensive review of the roles played by the airflow, wetting and spin finish on the air-jet texturing process is given. The results of an experimental investigation of the air-jet texturing process using residual spin finish, yarn-to-yarn static and kinetic friction, filament strength, filament diameter, and on-line tension measurements and h...

Pharmaceutical metered dose inhalers (MDIs) are drug delivery devices that are designed to produce self-propelled aerosols for inhalation therapies. Conventional MDI actuators use configurations based on a “two-orifice-and-sump” design. This promotes partial expansion of the propellant as a pre-atomisation stage. The final aerosol contains large nu...

Dry powder inhalers (DPIs) are portable, breath-actuated devices used for respiratory drug delivery. They have been the subject of intense research and development activity over the last 15 years, however, no systematic study of the effects of geometry on aerosol generation in DPIs has been reported in the literature. In particular, the first stage...

The non-premixed, bluff-body burner provides both an industrially significant flow configuration and an academically useful tool for the development and validation of predictive CFD models. The bluff-body configuration is used to provide flame stabilisation in burners ranging from a few kW to several MW. The unsteady nature of the flame/flow intera...

Cone-capillary nozzles with varying cone angles from 10° to 120° and a capillary diameter of 120μ are experimentally investigated for their application in the hydroen tanglement process. Cone-up and cone-down configurations in a range of water pressures of 30-120 bar are tested. The effects of the cone angle on flow parameters such as discharge and...

This article is closed access. It was published in the Journal of Heat Transfer [© ASME]. To obtain this article please visit the ASME Digital Library at: http://www.asmedl.org/ The ray effect is a serious problem in radiative heat transfer computations. Continuously varying radiation fields are approximated numerically by sampling a limited number...

This is an article from the journal, Proceedings of the IMechE, Part L: Journal of Materials: Design and Applications [© Professional Engineering Publishing ]. It is also available at: http://journals.pepublishing.com/content/119775/?p=6dbbadb9255c44c8a1d32e6233c53da4&pi=0 The image analysis techniques developed in Part 1 to study microstructural c...

This is an article from the journal, Proceedings of the IMechE, Part L: Journal of Materials: Design and Applications [© Professional Engineering Publishing ]. It is also available at: http://journals.pepublishing.com/content/119775/?p=44f278ddf2c54be5bfc051be5cfcc66a&pi=0 This paper reports image analysis methods that have been developed to study...

Exhaust Gas Recirculation (EGR) is one of several technologies that are being investigated to deliver future legislative emissions targets for diesel engines. Its application requires a detailed understanding of the thermo-fluidic processes within the engine's air system. A validated Computational Fluid Dynamics (CFD) process is one way of providin...

The aim of this paper has been to describe the novel approach adopted in studying the flow field within the Volumatic. In this study a combination of engineering tools such as Computational Fluid Dynamics (CFD), Laser Doppler Anemometry (LDA) and Flow visualization techniques have been employed. The initial part of the study involved the use of CFD...

This is an article from the journal, Clean Air [© Taylor & Francis ]. Most practical combustion systems involve complex geometry configurations and CFD techniques used for the calculation of flow and combustion in such geometries use body-fitted non-orthogonal mesh systems. This paper reviews some of the currently available radiative heat transfer...

Hydro-entanglement is a versatile process for bonding non-woven fabrics by the use of fine, closely-spaced, high-velocity jets of water to rearrange and entangle loose arrays of fibres. The cost of the process mainly depends on the amount of energy consumed. Therefore, the economy of the process is highly affected by optimisation of the energy requ...

In this paper image analyzing methods are established and presented to study the microstructural changes of the nonwovens made by hydroentanglement process. Fast Fourier transform is used to obtain the orientation distribution of the fibers. The distribution of the length of the straight segments of the fibers is evaluated by application of Hough T...

Pressurised metered dose inhalers (pMDIs) are widely used to treat lung disease and are under active consideration as more general means of drug administration. To improve the drug delivery efficiency of the pMDI and to widen its range of applications it is essential that the behaviour of the spray plume and its interaction with the oral cavity and...

This article is closed access. The conference proceedings are available from Begell House: http://www.begellhouse.com/references/1bb331655c289a0a,4d127640467b6621,79bbb77356de52c1.html In benchmark solutions the performance of radiation algorithms is normally studied by comparisons with the Monte Carlo method (MCM), since the latter is the only tec...

This article is closed access, it is an article from the journal, Numerical Heat Transfer, Part B [© Taylor & Francis]. The definitive version is available at: http://dx.doi.org/10.1080/104077900459176 The discrete transfer method ( DTM) is a widely used algorithm for the computation of radiative heat transfer in enclosures. The truncation error in...

The active fluid volume in an electromagnetic flowmeter is taken as a finite circular cylinder. The magnetic potential and virtual-current potential in this volume are expanded in Fourier series in the variables theta (polar angle) and z (axial coordinate). Any magnetic field and virtual current is thus represented by the matrices anm and bpq respe...

New designs of texturing and intermingling nozzles having a rectangular cross-section are investigated. The rectangular cross-section and the two-piece construction of the nozzle design, common features in both the texturing and intermingling nozzles, facilitate both manufacture and maintenance. Another novel feature of the design is that the air i...

A method is presented to quantify truncation errors in the discrete transfer method due to discretization of the heat flux integral (hemisphere discretization error) and enclosure boundaries (surface discretization error) for radiation problems involving transparent media. The hemisphere discretization error is generally the larger of the two. Its...

The truncation error in the heat flux integral associated with the discrete transfer method (DTM) is the difference between the actual heat flux and its approximation. Estimates of this error in radiative heat transfer problems in enclosures filled with a transparent medium were presented in a companion article [1]. Here we extend the methodology t...

This study investigates the effect of nozzle geometry on the intermingling process. The dimensions of intermingling nozzles with single air inlets extended across the width of a rectangular yam channel are systematically varied. Nozzles with this cross-sectional shape prove to be easy to manufacture and efficient at intermingling. The performance i...

An investigation of the third-order, non-linear, eddy-viscosity turbulence model of Craft et al (1996) has been performed to assess its predictive capability in a complex turbulent flow with recirculation. The model was implemented in the finite volume CFD code TEACH and applied to an axisymmetric pipe expansion. Here we compare the performance of...

This article is closed access, it is an article from the journal, Fire and Materials [© John Wiley & Sons, Ltd]. The definitive version is available at www3.interscience.wiley.com and the article can be viewed at http://dx.doi.org/10.1002/(SICI)1099-1018(199611)20:6<261::AID-FAM578>3.0.CO;2-M This paper reviews the past research, experimental techn...

This paper systematically investigates the effect of a number of geometric parameters on the texturing performance of air-jet texturing nozzles. In order to facilitate the research, an air-jet texturing nozzle with a rectangular cross section has been developed. The texturing performance of the nozzles is assessed by means of process observations a...

Air-jet texturing is a versatile process for producing a range of synthetic yarns with a spun-like appearance, which are widely used for apparel and furnishing fabrics and industrial textiles. There is no universal nozzle capable of processing any supply yam of any linear density. The role played by nozzle geometry is still not fully understood. Th...

If your new or interested in the field of CFD this book with introduction to cfd by john d anderson should be in your personal library.

This paper examines the effect of raised disruptions on the forced convective heat transfer coefficient for a plane surface. The work is of particular relevance to the mullion and/or transom configuration of the single-glazed elements of building facades, where window and atria framework design might play a significant role in determining heat loss...

The successful development of total hip replacement as an effective surgical technique has been one of the most significant advances in modern orthopaedics. The method has superseded the traditional forms of treatment for hip fractures which involve extensive nailing across the site of the break. However, clinical experience has highlighted failure...

An analytical expression obtained elsewhere for the change in virtual current due to conducting tubes at the ends of an electromagnetic flowmeter is used to determine corrections to the matrix representing the virtual current in a cutoff volume of the flowmeter interior. As described previously use of matrices to represent the virtual current and m...

Summary The mechanics of flow of propellant through the twin orifice of pMDIs (pressurized metered-dose inhalers) is complex and poorly understood. The quantitative prediction of flow variables inside pMDIs, from a fundamental point of view remains elusive due to the complex, unsteady, multiphase fluid dynamics that occurs in these devices. The pre...

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