ST Kolaczkowski, R Chao, S Awdry, A Smith
Application of a CFD Code (FLUENT) to Formulate Models of Catalytic Gas Phase Reactions in Porous Catalyst Pellets
Publication: Chemical Engineering Research and Design
Volume 85, Issue 11, 2007, Pages 1539–1552
Abstract: A method is described by which a CFD code known as FLUENT, may be adapted to model the reactions that take place inside catalyst structures. To test the CFD code, simulations of gas flow in a circular tube are performed and compared with analytical solutions. Then the coupled processes of diffusion and chemical reaction, combined with heat and mass transfer effects are modelled in a catalyst pellet. To illustrate the technique, the catalytic combustion of propane is simulated in spherical and cylindrical shaped pellets, at gas temperatures from 500 to 700 K and at atmospheric pressure. To help validate the approach adopted, the results of the CFD simulations are compared with solutions obtained from a one-dimensional model using MATLAB. It is shown that the CFD simulations provide comparable results with MATLAB, and that the CFD code can provide valuable additional information about temperature and concentration gradients in and around the catalyst pellet—this is not available in a simple one-dimensional approach. It is discussed how the technique could be extended to model reactions in a packed bed which would be a valuable design tool.
Smith MW (Dstl), Neininger E & Taylor K.
Adsorption modelling using Computational Fluid Dynamics
Publication: "Fundamentals of Adsorption 9 conference, Sicily (poster) and 'Adsorption' (Journal of the
Abstract: A computational fluid dynamics (CFD) based model has been developed to represent adsorption in activated carbon vapour filters. Experimental adsorption isotherm data is used to determine adsorption uptakes, with a linear driving force approach used to model the adsorption kinetics. Comparisons between experimental and modelled breakthrough curves for pentane vapour adsorbing onto BPL granular carbon show a qualitative match, although there is a systematic error caused by a mismatch between uptakes from the isotherm and the dynamic breakthrough experiments. Preliminary experiments show that the CFD model is able to replicate the effects of variable influent concentration on the effluent concentration-time profile.
Neininger E, Smith MW (Dstl) &Taylor K.
CFD modelling of adsorption in carbon filters
Publication: European PHOENICS User Conference, Wimbledon (presentation only)
Abstract: A CFD technique for predicting the performance of various types of carbon filter has been developed. Initial work concentrated on prediction of flow distribution and pressure drop within the filter units, and models of a range of filter geometries have been developed both using ‘packed bed’ and ‘monolith’ filters. More recently development of the model has focused on prediction of vapour adsorption, and considerable effort has gone into validating the predictions on a small scale packed bed filter.
Smith MW (Dstl), Neininger E, Smith AG & Taylor K.
The use of computational fluid dynamics to model adsorption in activated carbon filters
Publication: Carbon 2006, The International Carbon Conference, Aberdeen
Abstract: Computational fluid dynamics (CFD) offers a powerful method for studying flow distribution and adsorption in activated carbon filters. A model has been developed based on proprietary software (PHOENICS, CHAM Ltd, UK), with a front end enabling user input of filter dimensions and test conditions. The filter geometry and adsorbent physical properties determine the flow distribution within the filter, onto which adsorption phenomena are superimposed. At each cell within the computer generated grid, adsorption is modelled using experimental adsorption isotherm data to derive the capacity, with the adsorption kinetics assumed to follow a linear driving force algorithm. Experimental data has been acquired for breakthrough of pentane vapour through BPL carbon in a dry airstream, and this has been used for validation. The model has been shown to be capable of reproducing the effects of changing bed depths and flow rates on the breakthrough time, potentially offering a valuable filter design tool. The model is being developed to enable study of variable influent flow and concentration, conditions which are difficult and costly to replicate experimentally. Preliminary studies have also commenced to incorporate the effects of water vapour on filter performance, through adjustment of the capacity and kinetic terms in the model.
Smith AG, Smith MW (Dstl) & Taylor K.
Prediction of heat and mass transfer in canister filters
Publication: PHOENICS User Conference, Melbourne 2004
Abstract: Canister filters typically comprise of a cylindrical body containing a packed bed of material which can adsorb toxic gases and vapours from the air. In previous work, pressure drop prediction capability was created based on linking the Ergun equation to the derived voidage distribution within the packed bed. An adsorption model has also been added using suitable source terms for a contaminant. This paper describes the application of these physical modelling techniques to a respirator canister. The geometry of the canister is defined as a PHOENICS BFC mesh and the flowfield is solved with transient, i.e. breathing, flow boundary conditions.
A. G. Smith
An automated optimisation technique for rocket motor nozzle design based on Phoenics flowfield solution
Publication: Presented at Phoenics User Conference, Moscow 2002
Abstract: CFD has been in use for the prediction of rocket motor exhaust nozzles for many years. The problems of nozzle performance, surface heat transfer and chemical reaction are some of the reasons why analysis of this type is required. However, such analysis work has often been carried out with pre-existing designs or maybe with a few iterations of a given design. The pressure ratios used with rocket motors mean that a supersonic flow emanates from the nozzle. The shape of the nozzle is important for two reasons 1/ the exit velocity and pressure combine to provide the thrust and 2/ the shape of the nozzle throat determines the mass flow that the nozzle can pass. By modelling the nozzle flowfield in some detail, including the chemical reactions that might take place, the nozzle performance can be predicted. This work describes an automated technique for progressively modifying a nozzle geometrical parameter and recalculating the performance of the nozzle so that the performance can be optimised. An example is shown of the technique and recommendations are made with regard to future development work in this area. This work was initiated by QinetiQ with funding from UK MoD research package TG06.
Smith AG & Cretella A (Fiat Avio).
The problem of exhaust plume radiation during the launch phase of a spacecraft
Publication: PHOENICS User Conference, Moscow, September 2002
Abstract: Calculations have been made of the radiative heat transfer from the plume of a solid propellant motor to the launch vehicle surface. CFD (using PHOENICS as the core solver) has been used to provide predictions of the exhaust plume flowfield. This data has then been translated to a post-processing system (FEMVIEW) for radiation calculations to be made. These calculations have included the effect of particulates present within the gas stream. Individual lines of sight from various positions along the vehicle surface through the plume have been considered. The incident radiance for each line of sight has been calculated using a wide bandwidth of the infrared spectrum. The influence of progressively steeper lines of sight through the plume have been considered and total irradiance at each location has been calculated. The calculated values of irradiance at the surface are potentially detrimental to the 3rd stage motor and measures are required to protect it.
Eustace RM & Smith AG.
Possible modifications to the standard two-equation turbulence models in order to improve prediction of turbulent mixing rates for problems involving jet mixing
Publication: FLUENT User Conference, Rotherham, September 2002
Exhaust silencer transient analysis
Publication: FLUENT User Conference, Sheffield
Newman S (DERA), Rooks S (DERA), Bull C (DERA), Green J, Taylor K & Smith AG.
Validation of SAPPHIRE Heat Transfer Predictions
Publication: Proceedings of 12th Ground Target modelling and Validation conference, Houghton, MI
Abstract: Platform infrared (IR) signature prediction requires detailed information about detailed surface temperature distribution. The thermal modelling techniques, which provide such temperature distributions, rely on an ability to predict the combination of convection, conduction and radiation. As these techniques develop, validation of the methods used is required. this paper describes work to validat full-scale thermal modelling techniques as used in the Dstl SAPPHIRE codes. The prediction of helicopter tail boom heating from gas turbine exhaust flow and subsequent IR signature prediction is compared with temperature and IR measurements made using a real tail boom and Gnome (T58) engine exhaust flow. The correct prediction of plume temperature distribution has proved critical to obtaining a realistic hard body surface temperature distribution.
Eustace RM & Smith AG.
Aircraft infra-red signature prediction
Publication: FLUENT User Conference, Sheffield, September 2000
Taylor K, Smith AG, Ross S (DERA) & Smith MW (DERA).
CFD modelling of pressure drop and flow distribution in packed bed filters
Publication: PHOENICS Journal of Computational Fluid Dynamics and its applications, 2000, 13 no 4, 399-413
Abstract: A CFD technique for predicting the performance of axisymmetric packed bed filters has been developed.
Smith AG & Taylor K.
Modelling of two-phase rocket exhaust plumes and other plume prediction developments
Publication: PHOENICS Journal of Computational Fluid Dynamics and its applications, 2000, 13 no 1, p13-28
Abstract: Combustion processes result in the creation of an exhaust flow. The exhaust is released into the atmosphere creating a plume. A knowledge and understanding of the exhaust plume flowfield can be important for a number of reasons such as thermal or aerodynamic loading from impingement, infrared signature prediction or environmental considerations (e.g. diesel particulates). Software exists for the prediction of plume flowfields from a number of powerplant types. This software has been developed over several years and uses PHOENICS as the core solver. This paper describes recent developments of the plume prediction software carried out to enhance its capabilities and applications. The particular areas that are described in this paper are 1/ the implementation of a limited two phase capability, 2/ the application of the PHOENICS enhancements to the parabolic capability for underexpanded flows, 3/ the feasibility of using parallel PHOENICS for plume predictions, 4/ the prediction of transient phenomena within plumes.
Eustace RM & Barrett RV (U of Bristol).
The use of suction to suppress disturbances in laminar flow caused by insect and other surface debris
Publication: Proceedings of Institution of Mechanical Engineers, vol 213,Part G., pp. 277 - 292
Abstract: Aircraft that employ extensive laminar flow for drag reduction need measures to counter the potential breakdown to turbulence caused by surface debris picked up near the ground. Decontamination methods are being developed but may not be suitable where suction through microperforated skins is used to control the flow, owing to the likelihood of hole blockage. This paper examines an alternative, where the existing suction system is used to draw away the developing turbulent wedges behind individual particles, thus providing a degree of tolerance to surface contamination. A wind tunnel investigation was conducted, using a flat plate model with a configurable suction region, to simulate the essential features of the boundary layer on a laminar flow engine nacelle. This enabled the influence of the various flow and geometric parameters to be assessed. The results, taken at Reynolds numbers/m in the range 1.5--4.5 Ã— 10[sup 6], showed that turbulent wedges could be stabilized and removed, but that this required high levels of suction. The attendant increases in drag and suction system power make the method unattractive economically, although this situation would change if the increased suction could be applied only where required. The condition of self-induced transition at high suction flows was also investigated and was shown to limit the speed at which particle-induced turbulence could be suppressed.
Taylor K, Smith AG, Ross S (DERA) & Smith MW (DERA).
The prediction of pressure drop and flow distribution in packed bed filters
Publication: 2nd International Conference on CFD in the Minerals & Process Industries, CSIRO, Melbourne
Abstract: A CFD technique for predicting the performance of axi-symmetric packed bed filters has been developed.
Eustace R & Smith AG.
Application of different CFD grid generation strategies to aircraft infrared signature prediction
Publication: I Mech E seminar on CFD: technical developments and future trends
Rooks S(DERA), Hayward L(DERA) & Smith AG.
The use of PHOENICS for modelling helicopter flowfields.
Publication: PHOENICS Journal of Computational Fluid Dynamics and its Applications 1998, 11 no 1, p103-112
Abstract: The Electro-Optic Signatures section at DERA Farnborough is concerned with prediction of the infrared signature of air-vehicle platforms. In order to evaluate the thermal characteristics of the airframe surface and exhaust gas flow field for a given flight condition, a series of codes have been developed which use PHOENICS as the core solver. These codes are collectively known as SAPPHIRE. One of the more complex modules of SAPPHIRE, the Helicopter model, considers the interaction of exhaust gases with the main and tail rotors, an essential pre-requisite for accurate prediction of the resulting flow field and hard body infrared signature. This paper will provide an overview of the SAPPHIRE Helicopter Model, including grid generation, incorporation of sub-models, boundary condition representation, and conclude with some recent flow field evaluation exercises.
Rooks S (DERA) & Smith AG.
Flowfield and IR Signature Modelling for Ground Targets.
Presented at the Proceeding of the Eighth Annual Ground Target Modelling and Validation Conference - Houghton, MI, August 1997
Abstract: The Electro-Optic Signatures section at the UK's Defence Evaluation and Research Agency (DERA) is principally concerned with the prediction and control of air-vehicle infra-red signatures. The accurate modelling of plume flowfields is fundamental to a realistic IR signature prediction. This has been made possible through the development of appropriate CFD models which have been validated across a wide range of vehicle types. In addition to the flow field models, a number of IR signature prediction codes have been developed to make use of the CFD data to provide complex three dimensional signature assessment.
In order to obtain a complete flow field prediction capability for air-vehicle platforms such as helicopters it has been necessary to extend the plume prediction capabilities to include complex geometrical and flow field features. This has led to the development of a suite of programmes know as SAPPHIRE which for the case of helicopters is capable of considering flow field interactions between the rotors, exhaust plume (including effects of IR suppressors), free stream and ground effects. This paper describes the plume flow field prediction capabilities and how they have been developed within SAPPHIRE to provide a complete platform level signature prediction technique. An example illustrating the use of SAPPHIRE for assessing a typical helicopter flow field and IR signature will be presented.
Smith AG & Taylor K.
The simulation of an aircraft engine intake anti-icing system.
Publication: PHOENICS Journal of Computational Fluid Dynamics and its applications, 1997, 10 no 2, p150-166
Abstract: A PHOENICS model has been created to simulate the flow and heat transfer associated with the Jetstream 41 aircraft engine intake system. The 2D model allows the external aerodynamics, the internal heating flows, and the conjugate heat transfer through the skin of the airframe to be determined at the centreline of the intake. GENTRA is used to evaluate the trajectories of typical super-cooled water droplets as they approach the intake. Using the impact data resulting from the GENTRA run, source terms are added to the energy equation to take account of the cooling effect of the water impingement. The effectiveness of the anti-ice system can then be determined. Validation against existing flight data has been carried out and agreement is generally speaking good. The model has been used to simulate a number of cases in support of airworthiness certification for a new intake design.
Smith AG & Taylor K.
CFD prediction of exhaust plumes and interaction with superstructures.
Publication: TRANSACTIONS- INSTITUTE OF MARINE ENGINEERS -SERIES C-; 109, part 1; p55-62 Application of fluid dynamics in the safe design of topsides and superstructures
Abstract: A software system has been produced to model the dispersion of exhaust plumes and their interaction with the superstructure in order to predict the plume shape and resultant IR signature. A general purpose, commercial CFD code linked to a specially developed pre-processor is used to predict the plume flowfield, temperature and gaseous species distribution. This data is then post-processed using a line-of-sight algorithm to calculate the spectral radiance and apparent temperature.
The system takes into account multiple plumes, exhaust composition, blockage effects of the superstructure and wind effects.
This paper describes the main components of the system and the physical models embodied in each. At the time of writing, the system is still under development, but some preliminary results are also presented here.
Nozzle and exhaust plume flow and heat transfer.
Presented at the Royal Aeronautical Society Conference on Engine Airframe Integration, 10th & 11th October 1996.
Publication: Published in the Propulsion Conference Proceedings. Paper 5. ISBN 1 85168 092 8.
Abstract: S&C Thermofluids Ltd is involved with the prediction and small scale testing of the flow and heat transfer associated with aircraft and missile propulsion systems. A general purpose prediction capability has been created for allowing rapid assessment of flow and heat transfer within both circular and rectangular nozzle systems including transition ducts. The main requirement for this capability is in the determination of the infra-red signature associated with the nozzle surfaces and the subsequent plume. The code allows for the transport of chemical species to be predicted along with any associated reactions. The capability has undergone extensive validation against experimental measurements. A number of nozzle designs aimed at signature reduction and thrust vectoring have also been examined using similar techniques and small scale experiments have been carried out to validate the result. This paper reviews the progress within this on going research programme.
Some operational considerations of using PHOENICS
Publication: PHOENICS Journal of Computational Fluid Dynamics and its applications 1996, 9 no 1, p1-9
Abstract: S&C Thermofluids Ltd has been applying PHOENICS to a wide range of cases over the last nine years. Attention has been given to the effective use of the code, particularly in the areas of geometry specification, boundary condition settings, and choice of solution algorithms. The aim of the paper is to review some of the operational aspects of using PHOENICS. These are chiefly in the areas of geometry specification via CAD data, use of the parabolic solver and use of the conjugate heat transfer capability. These areas will be reviewed with the aid of specific examples - namely - a cylinder head cooling flow, exhaust plumes, and missile aerodynamic heating. The paper aims to highlight both advantages of the techniques and some deficiencies.
Smith AG, Taylor K, Kopmels M & Rooks S (DERA) et al.
The use of PHOENICS in aircraft infra-red signature prediction
Publication: PHOENICS Journal of Computational Fluid Dynamics and its Applications, Vol. 7 No. 4, pp 126-149, 1995 95/34
Abstract: A system has been created to allow infra-red signatures of aircraft to be evaluated. The system handles aircraft, helicopter and missile types. PHOENICS is used to provide the flowfield and heat transfer modelling capability of the system. The system can take simples or rigorous geometry specification with subsequent generation of grids suitable for use with PHOENICS. Flight conditions are translated into CFD boundary conditions and solution controls. User ground subroutines are provided to calculate additional source terms. The output is automatically interfaced for use with infra-red prediction software. Flowfield interactions with complex exhaust plumes can be modelled via sub-models. For helicopters a special sub-model has been created for the prediction of rotor downwash. Validation and testing of the software is currently underway.
Smith AG & Kopmels M.
Prediction of Coanda effect flow fields.
Presented at the 5th International PHOENICS User Conference, Nice, September 1994.
Publication: Published in the International PHOENICS Journal Vol. 6, No 4 1994, pp 408-426 92/39
Abstract: A design tool, in the form of a Coanda effect model, had previously been developed for an internal axi-symmetric Coanda nozzle. The model was found to give good comparison with experimental results. The work was reported at the 4th International PHOENICS Users Conference.
This paper reports on the work which has been undertaken with an extended Coanda effect model. Grid generation programs were updated to include flow fields for 2D and 3D, internal and external Coanda nozzles.
The Coanda effect design tool was used in the development of a gas burner, a cooling device for high and low pressure flows and an automotive catalyst. The experimental results obtained from the constructed devices are compared with those originally predicted.
PHOENICS was able to predict the flows in the cases presented with a varying degree of success. Flow separation in the cooling device, with the high pressure flow, was predicted. It was successfully used to redesign the shape of the Coanda surface which enabled this flow to remain attached. In the case of the burner, the flow was predicted to remain attached to the surface, but in practice the flow separated.
Veneri R (Alenia Spazio SpA), Parodi P (Alenia Spazio SpA), Glynn D (Flowsolve Ltd) & K Taylor.
CFD Modelling of fire detection and suppression in a Columbus rack
Publication: Proceedings of 1994 European PHOENICS User Conference
Smith AG, Ayris JN & Beasley J (Royal Ordnance).
The modelling of blast wave propagation using PHOENICS.
Presented at the 5th International PHOENICS User Conference, Nice, September 1992.
Publication: International PHOENICS Journal, Vol. 6, No 3 1993, pp 325-341 & Hi-Hx 92/28 bp
Abstract: PHOENICS has been applied to the problem of blast wave propagation from an explosive source. The aim is to allow stress levels within a structure such as an aircraft to be evaluated, when subject to such forces. PHOENICS Q1, Satellite, and Ground coding have been produced which allow the setting up of three-dimensional, transient blast simulations. Consideration has been given to the way in which a suitable PHOENICS boundary condition could be formulated from a knowledge of the quantity of a given explosive material Several options have been provided for such formulation. The model has been applied to some idealised cases. The results appear to be realistic, although some effects of grid resolution were noticed. The model needs to be validated against experimental data.
The prediction of air breathing engine and rocket motor exhaust plume flowfields and infrared signatures.
Presented at the 5th International PHOENICS User Conference, Nice, September 1992.
Publication: Published in the International PHOENICS Journal Vol. 6, No 4 1993, pp 427-451 92/29
Abstract: Coding has been developed to enable 3D plume infra-red signatures to be determined. BFC based models of transition duct and convergent-divergent nozzle flows have been created in order to provide nozzle exit plane conditions for round, rectangular and elliptic nozzle shapes. Satellite coding has been written which produces suitable PHOENICS settings for grid, variables, initial fields, boundary conditions and under-relaxation from user's air breathing engine or rocket motor performance data, Three dimensional exhaust flowfields have been studied using this capability. Flows from rectangular nozzle, twin nozzle and three nozzle arrangements are presented. In all cases chemical species are modelled, but reactions are included only for the rocket exhausts. An interface has been created to a 3D infra-red signature prediction code to allow radiance levels in a given bandwidth to be calculated from the predicted plume flowfield. The PHOENICS-IR3D system is currently undergoing extensive validation.
Smith AG & Wu CML.
Use of PHOENICS for modelling chemically reacting rocket exhausts.
Publication: Bp Vol. 4, Suppl.1, pp 22-42 PHOENICS Journal of Computational Fluid Dynamics. Published by CHAM 91/32
Abstract: The coding from an existing 2D, axisymmetric, fixed geometry rocket exhaust model has been implemented within PHOENICS. This is to provide a versatile 3D rocket exhaust plume modelling capability. In the present version of this model, 18 species can be chosen from a list of 182, and 40 possible reactions can be handled from a choice of 236. The solution of chemical kinetics can be achieved either by producing PHOENICS type source terms for use in the Tri-Diagonal Matrix Algorithm or by use of a Fast Chemistry Solver, based on the CREK code, operating independently of the PHOENICS solver. The latter method of solution is advantageous for flows dominated by reaction rather than mixing. A detailed description of the way in which this implementation is achieved within PHOENICS is presented. The hope is that users could adopt similar methodologies for modelling chemically reacting flows. Such a method might be applicable to studying N0x problems. Results from using the code are presented. The likely areas of future development of this code are described.
Smith AG & Kopmels M.
Modelling of Coanda effect devices using PHOENICS.
Publication: PHOENICS Journal of Computational Fluid Dynamics Vol. 4 Suppl.1, pp 84-119. Published by CHAM 91/33
Abstract: A design tool has been produced for internal axisymmetric and plane two dimensional Coanda effect nozzles. The tool is based on PHOENICS predictions of nozzle flowfield and overall performance, and consists of a BFC grid generation program and a Q1 input file. Ground coding is used to enhance the model although this is not essential to obtain realistic predictions of Coanda effect device flowfields. The model has been applied to a number of different design problems. The predictions have been found to give acceptable levels of agreement with measurements and the tool has proved useful in the design of a rotary engine exhaust nozzle.