Fluid flow and heat transfer in cavities partially filled with disconnected blockages is important in the design of a wide range of industrial and engineering applications such as thermal management of indoor environments, cooling of electronic panels, drying of agricultural products, stacking of items in cold storage etc. The flows in such confined spaces develop as a result of temperature and concentration gradient which is further complicated by the interactive effects of turbulence and radiation. The aims of this research are to explore the detailed heat transfer and flow field inside cavities partially filled with solid blockages and, in particular, to address the uncertainties associated with turbulence models, to quantify the influence of double diffusion and to study the effect of surface properties. To achieve the above aims, a systematic numerical investigation has been carried out by validating the computational results against reliable experimental data available in open literature. A selection of turbulence and radiation models has been employed to scrutinise the effects of the above flow physics. An experimental set up capable of establishing low Rayleigh number buoyancy driven flow in a rectangular cavity containing cylindrical blockages was designed and fabricated to obtain temperature data. A series of experiments was conducted to obtain reliable temperature distribution at various positions in the flow domain and on the surfaces of the blockages. This set up also allowed us to study the proximity effect of blockages which has not been reported elsewhere. It has been found that the choice of turbulence model remains to be an important issue and should be given due consideration for natural convection flow with a high Rayleigh number. The results from the parametric study on the specification of passive thermal boundary conditions reveal that the experimental temperature profile is the most accurate boundary condition for passive walls in relation to the adiabatic and linear temperature profiles. Experimental benchmark temperature data evaluated at various positions in the cavity with and without blockages are presented and some of them are compared with CFD simulations. Finally, as an example of the application of the research methodology, a detailed numerical modelling was conducted on a Double-Skin-Façade which is known to reduce energy consumption in building and has become popular in recent years. The current methodology has been applied to establish a number of parameters in connection with the design and performance of DSF which are believed to be useful to practitioners.

This research is focused on the performance evaluation of micro Combined Heat and Power (mCHP) systems based on modern prime mover technologies using both theoretical and experimental analysis. Estimations of the environmental and economic impact associated with their deployment in residential conditions were also carried out. Experimental work was performed on assessing the dynamic and steady-state performance of the 1 kWe Stirling based mCHP system (Whispergen), the 0.75 kWe Proton Exchange Membrane Fuel Cell (PEMFC, PA Hilton Ltd) and the 5.5 kWe Internal Combustion Engine (ICE) based mCHP (Dachs). Results obtained from experiments (such as partial efficiencies, nominal capacities etc.) were fed directly in a theoretical model. Primary energy requirements corresponding to average UK domestic conditions were simulated based on real life technical data. All theoretical work was conducted using EnergyPlus building simulation tool in which the operation of several hydronic heating systems was modelled. Furthermore, attained experimental data and previously published research results were used to validate the theoretical modelling process. Several operating strategies of the Stirling based mCHP unit were simulated in order to determine the regime which offers highest reduction in carbon emissions and household expenditures. In addition, variations in a number of parameters that significantly affect the performance of the system were investigated including energy consumption profiles, occupancy characteristics, dwelling thermal requirements, domestic hot water tank volume, etc). For the optimum performance strategy, several configurations of co-generation systems with nominal capacity in the range from 1 to 3 kWe were simulated. All simulated mCHP scenarios were compared against a conventional heating equipment. Finally, the advantages of a mass installation on a district level, consisting of 60, 120 and 240 dwellings and utilising a mixture of different mCHP units (ICE, Stirling, PEMFC), were estimated.

This project aims to develop efficient and robust tools for optimal design of wind turbine adaptive blades. In general, wind turbine adaptive blade design is an aero-structure coupled design process, in which, the evaluation of aerodynamic performance cannot be carried out precisely without structural deformation analysis of the adaptive blade. However, employing finite element analysis (FEA) based structural analysis commercial packages as part of the aerodynamic objective evaluation process has been proven time consuming and it results in inefficient and redundant design optimisation of adaptive blades caused by elastic-coupled (bend-twist or stretch-twist) iteration. In order to achieve the goal of wind turbine adaptive blade integrated design and analysis, this project is carried out from three aspects. Firstly, a general geometrically linear model for thin-walled composite beams with multi-cell, non-uniform cross-section and arbitrary lay-ups under various types of loadings is developed for implementing structural deformation analysis. After that, this model is validated by a simple box-beam, single- and multi-cell wind turbine blades. Through validation, it denotes that this thin-walled composite beam model is efficient and accurate for predicting the structural deformations compared to FEA based commercial packages (ANSYS). This developed beam model thus provides more probabilities for further investigations of dynamic performance of adaptive blades. Secondly in order to investigate the effects of aero elastic tailoring and implanting elastic coupling on aerodynamic performance of adaptive blades, auxiliary software tools with graphical interfaces are developed via MATLAB codes. Structural/material characteristics and configurations of adaptive blades (i.e. elastic coupling topology, layup configuration and material properties of blade) are defined by these auxiliary software tools. By interfacing these software tools to the structural analysers based on the developed thin-walled composite beam model to an aerodynamic performance evaluator, an integrated design environment is developed. Lastly, by using the developed thin-walled composite beam model as a search platform, the application of the decoupled design method, a method of design of smart aero-structures based on the concept of variable state design parameter, is also extended.

Bandsawing is an important metal cutting operation carried out in a variety of industries in order to remove raw material for secondary operations. Due to its continuous cutting action, bandsawing has over taken other cutting processes such as power hack sawing and circular sawing. Bandsawing operation offers numerous advantages such as high cutting rate, low kerf loss, longer tool life and high automation possibilities, due to its efficient and continuous cutting action. It is costly and time-consuming to test the wear of the full bandsaw products on a full-scale bandsaw machine. In order to overcome this, a single tooth test rig has been developed at Northumbria University, which utilizes a single bandsaw tooth instead of the complete bandsaw loop. Previous research has utilized this test rig for evaluating bi-metal saws while machining steels. Development of new, wear resistant and difficult-to-cut materials such as titanium alloys (e.g. Ti-17) imposes greater demands on bandsawing operations. Traditionally, high speed steels and cemented carbides have been employed to cut/machine these materials. The main disadvantage of high speed steel cutting tools is that it undergoes severe plastic deformation when cutting at temperatures above 600oC. Tungsten carbide cutting tools have proven their supremacy in almost all the machining processes and interrupted cutting of these difficult-to-cut titanium alloys. One of the challenges in design of cemented tungsten carbide tools is the optimization of toughness and wear resistance. This has led to the development of coated carbide tools, which accounts for the major portion of all commercial metal cutting inserts sold worldwide. This current research has furthered the use of single tooth test rig, by using un-coated and coated tungsten carbide tipped bandsaw blades while machining high performance titanium alloys (Ti-17). The purpose is to evaluate and assess the performance of un-coated and coated carbide bandsaw teeth and ascertain wear mechanisms and modes of single bandsaw tooth, in a way that is representative of full product testing. Two different coatings (AlTiN and TiAlSiN) were chosen to be deposited using arc evaporation PVD technique. These coatings were selected due to their properties in terms of wear resistance and structure: TiAlSiN is nano-structured, while AlTiN is conventional in terms of its grain size. These coatings were characterized using various techniques, such as electron microscopy and nano-indentation. Cutting tests were carried out using un-coated and coated carbide bandsaw teeth. Adhesive wear and diffusion wear were identified as the wear mechanisms, while flank wear and chipping were confirmed as the principal wear modes for the un-coated carbide bandsaw teeth. Cutting forces were found to be less while machining Ti-17 alloy using coated teeth as compared to the forces obtained while machining with un-coated teeth. Less material was found to be adhering to the coated teeth as compared to un-coated teeth. Finite element analyses (FEA) were carried out on interaction of the cutting tool and the workpiece to determine the stress concentration during the cutting process. It was found that the increase in the honing lengths on the carbide teeth reduced the stresses and moved the maximum stress from the edge of the rake face to the honed edge.

The objective of this work was to understand the mechanics of material removal during rock cutting. The exact nature of the failure of the rock material at the tool tip was investigated using a single cutting tooth test rig coupled with high speed photography, for various rock-like specimens. Linear cutting tests were performed using a tungsten carbide tipped orthogonal cutting tool with three different rake angles on low and high strength simulated rocks. Statistical analysis together with high speed video analysis were supported by numerical simulation, performed using a commercially available code called ELFEN; a hybrid finite-discrete element software package.

Several sophisticated procedures for balancing flexible rotors have been developed during the past two decades. For a variety of reasons, none of these methods has gained general acceptance by practicing balancing engineers. Some of these balancing techniques require a great deal of expertise from the operator. This thesis is dedicated to the research of flexible rotor balancing techniques, and aims to apply some advanced techniques to the field of high-speed rotor balancing. Significant progress in balancing methods for flexible rotors can be achieved by the improvement and optimization of existing balancing techniques. Experimental tests were conducted to demonstrate the ability of the influence coefficient method to achieve precise balance of flexible rotors. Various practical aspects of flexible- rotor balancing were investigated. Tests were made on a laboratory quality test rig having a 3.6 m long rotor representing a High Pressure Turbine (H.P.T) (10.1 kg)(43.767 cm), a Low Pressure Turbine (L.P.T) (43.922 kg) (113.698 cm) and a Generator Rotor (G. Rotor) (71.611kg) (146.413 cm) and covering a speed range up to 6000 rpm. A specific data acquisition system has been developed for use in a high-speed rotor balance facility. Special measurement requirements for this facility include order-tracked vibration measurements and phase angle data. The data acquisition system utilizes dual high-speed computer systems to share the tasks of measurement data processing, and results display. A study of balancing errors is systematically discussed in detail from the view point of increasing the balancing precision. The methods for controlling and reducing these errors are also discussed. Both the qualitative and quantitative analyses of balancing errors are performed as the guide to reduce the error and improve the balancing quality. The thesis also presents the theoretical background and the techniques necessary to the procedure to balance the flexible rotor. A trim balancing method was developed to expand the implementation of flexible rotor balancing. A computer program has been written which generates influence coefficient from measured motions and goes on to predict the correction mass. The vibration has been measured at several locations and speeds and the results have been used to (a) ensure that the vibration levels were not excessive as the rotor speed increased and (b) to calculate the balance correction weights using the traditional influence coefficient method and a least squares influence coefficient method. The procedure developed was verified using an experimental rotor rig. The successful application of the procedure to the balancing of this rotor demonstrates that balancing using Singular Value Decomposition, QR Factorization, and QR Factorization combined with SVD and new trim balancing method is not only a theoretical but also a practical possibility. The Moore-Penrose generalized inverse has been employed to solve the problem. The dynamic characteristics of the rotor rig, however, were somewhat limited and did not cover all the possibilities considered during the project. Therefore, a more complete numerical example was also successfully solved using the computer model of a rotor with characteristics similar to those of a real turbine by using a finite element software package called ANSYS.

Currently heating, ventilation and air conditioning (HVAC) systems are difficult and costly to monitor for energy efficiency performance and reliability. As buildings evolve, they will require higher levels of insulation and air tightness which will require ventilation systems to provide the minimum number of air changes and reduced energy usage by recovering heat from the air before it is expelled. This will necessitate the need for monitoring of the operating performance of these systems so that air quality or building energy efficiency is not detrimentally affected. A typical duct airflow monitoring device uses a pressure differential method to determine the airflow rate but they are fragile, expensive and create an additional pressure loss. The monitoring of airflow rates can indicate problems in the design, installation and operation of a HVAC system. One of the possible alternatives to using pressure differential type devices such as Pitot tube/arrays, orifice plates and Venturis is to use an ultrasonic flow rate sensor, but historically their high cost has restricted their use in HVAC systems. This project has looked at improving on existing measuring systems by developing an ultrasonic in-duct flowmeter system to measure the mean airflow, temperature and humidity of a ventilation duct so that a comparative energy level can be accurately deduced. A proof of concept in-duct ultrasonic airflow monitoring device has been developed and has obtained results within ±3.5% RMS of a Venturi airflow measuring device. Matlab code for a Monte Carlo acoustic ray/particle tracing ultrasonic flowmeter simulation has been developed to study the effects of non-ideal installation scenarios. The fully developed centreline computational fluid dynamics (CFD) mean flow velocity to duct total mean flow velocity error can be up to 13%. Analysis of the CFD data for various duct scenarios has shown that this could be reduced to below 5% by using a transducer offset of approximately ±0.25 duct diameters or widths from the centreline at distances as close as one duct hydraulic diameter from an upstream disturbance, such as caused by a bend.

This study is carried out to investigate the solar thermal energy conversion for generating power. This form of renewable energy can be utilised for power production deploying the free piston Stirling engines, which convert thermal energy into mechanical energy. Such systems have an advantage of production of work using low and high temperature differences in the cycle which could be created by different sources of heat including solar energy, combustion of a fuel, geothermal energy, nuclear energy or waste heat. The thermodynamic analysis of the free piston Stirling engine have been carried out and implemented in past studies with different methods of approach with various difficulties exhibited. In the present study isothermal, ideal adiabatic and Quasi steady flow models have been produced and used for investigation of the engine performance. The approach in this study deals with simultaneous mathematical modelling of thermodynamic processes and pistons dynamics. The steady state operation of the engine depends on the values of damping coefficients, spring stiffness and pressure drop within the heat exchangers during the engine’s operation, which is also a result of the energy transfer in each engine’s component. In order to design effective high performance engines it is necessary to develop such advanced mathematical models to perform the analysis of the engine’s operation and to predict its performance satisfactorily. The aim of this study was to develop several levels of mathematical models of free piston Stirling engines and to evaluate their accuracy using experimental and theoretical results available in published sources. The validation of the developed free piston Stirling engine models demonstrates a good agreement between the numerical results and experimental data. The validated model then was used for optimisation of the engine, deploying Genetic Algorithm approach with the purpose to determine its optimal design parameters. The developed optimisation procedure provides a noticeable improvement in the engine’s performance in terms of power output and efficiency.

Solar energy has been actively used to drive cooling cycles for domestic and industrial applications, especially in remote areas with a lack of electricity supply for running conventional refrigeration or air-conditioning systems. A number of solar cooling technologies exists but their market penetration level is relatively low due to the high capital costs involved and a long pay-back period. Extensive R & D activities are underway at Universities and industrial companies across many countries to improve performance and reduce capital and running costs of solar cooling systems. Systems based on application of a liquid piston converter for solar water pumping and dynamic water desalination have been developed at Northumbria University. Some preliminary work has been completed on the development of a new solar cooling system built around the above fluid piston converter. In this work, the task is to experimentally and numerically investigate performance of the solar cooling system with the fluid piston converter. The developed theoretical model then can be used for determination of its rational design parameters. Experimental tests were conducted in the Energy Laboratory of the Faculty. The test rig consisted of a solar simulator and evacuated tube solar collector, coupled to the liquid piston converters, equipped with a heat exchanger. Three different configurations of the solar cooling unit were tested and a data acquisition system with pressure, temperature and liquid piston displacement sensors was used to evaluate the experimental performance on the cooling capacity. In the theoretical part of the study, the thermodynamic model of the solar cooling system was developed. In the calculation scheme, the system was split into a number of control volumes and ordinary differential equations of energy and mass conservation were used to describe mass and heat transfer in each such volume. The system of ordinary equations then was solved numerically in MATLAB/Simulink environment and information on the variations of pressure and temperatures in the control volumes of the system over the cycle were obtained. Calibration of the mathematical model with the use of experimental data demonstrated that the model predicts the performance of the system with accuracy acceptable for engineering purposes. Experimental investigations showed that laboratory prototypes of the system demonstrate a stable operation during the tests with an amplitude and frequency of liquid piston oscillations being about 4- 6 cm and 3 Hz, respectively. The reduction in the air temperature in the cooling space was about 1 and 2 K, compared to the ambient temperature. The cooling effect increases with the raise in the heat input into the solar collector and in the flow rate of cooling water. The developed mathematical model of the system describes the pressure variation in the cycle, amplitude and frequency of oscillation of pistons with a level accuracy sufficient for performing engineering design calculations. Overall, both experimental and theoretical investigations confirm that the system demonstrates a capacity to produce a cooling effect with utilisation of solar energy. However, further R & D is required to enhance its performance.

This research is in the field of CFD modelling of heat engines, particularly the advanced CFD methodologies for the performance characterization of solar Stirling Engines with complex geometrical topologies. The research aims to investigate whether these methods can provide a more inclusive picture of the engine performance and how this information can be used for the design improvement of Stirling engines and the investigation of more complex engine topologies.