Browsing by Author "Anselmi, Eduardo"
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Item Open Access Design and optimization of a Tesla pump for ORC applications(Technical University of Munich, 2021-10-11) Anselmi, Eduardo; Fiaschi, Daniele; Nicotra, Giovanni; Talluri, LorenzoThe Tesla pump is bladeless turbomachinery known for being more resistant to work with hard-to-pump fluids than conventional turbomachinery, thanks to its simple, robust mechanical design and its working principle (viscous forces). A 2D numerical model is developed and a design procedure of a Tesla pump working with several working fluids (water, R1233zd(E), R1234yf) is proposed. A complete design methodology is developed by evaluating the losses of each component and by introducing a rotor model. The main optimizing parameters of the pump are highlighted and assessed and validation of the model with available experimental results is carried out. A design procedure for a Tesla pump prototype is showed and its characteristic curves are obtained and discussed. The results achieved are similar to other experimental Tesla pumps, with a maximum achieved efficiency of 26.8%. The extension of the model to organic working fluids allowed to predict pump efficiencies higher than 50% for low mass flow rate conditions for both assessed fluids.Item Open Access Development of an experimental S-CO2 loop for bottoming cycle applications(Unknown, 2016-10-11) Anselmi, Eduardo; Zachos, Pavlos; Collins, Robert; Hassan, MarkThis paper describes the design of a supercritical carbon dioxide [S-CO2] rig for bottoming power cycle applications. The final envisaged layout of the facility includes a fully coupled compressor-turbine system, a number of heat exchangers to enable heat management of the cycle and a control system for start-ups, shut-downs, inventory control and transient operation of the loop. The objective of the preliminary design phase is to experimentally de-risk the robustness of the closed loop system as well as prove the purpose of individual components and various measurement and control modules.Item Open Access Effect of mixing Mach number and mixing efficiency on the preliminary cycle design of mixed high-BPR turbofans(Elsevier, 2019-03-02) Cleton, Bjorn; Anselmi, Eduardo; Pellegrini, Alvise; Pachidis, Vassilios; Laskaridis, PanagiotisThis article presents the implementation of an updated analytical flow mixing model in a state-of-the-art, non-dimensional gas turbine cycle performance simulation and optimisation tool. The model considers three separate streams in the mixer, each expanding through its own ‘virtual’ nozzle. The use of three streams, compared to one single stream, allows for a more realistic simulation of a mixed exhaust gas turbine. This approach is used in a parametric study to assess the effect of the choice of mixing efficiency and mixer inlet Mach number on the preliminary design of mixed-exhaust, high-bypass ratio turbofan engines. It was found that in terms of best thermal performance, a trade-off exists between mixer inlet Mach number and mixer effectiveness. The findings of this research establish some useful guidelines for the accurate selection of these two parameters to achieve robust cycle designs.Item Open Access Insights into the flow field and performance of a boundary layer pump(American Society of Mechanical Engineers, 2023-10-19) Rajendran, David John; Palaveev, Kyril; Anselmi, Eduardo; Santhanakrishnan, Mani; Pachidis, VassiliosA flow field analysis of a realistic, integrated, multi-disc boundary layer pump as is necessary for investigating the reasons for typically quoted low efficiencies in such pumps is described. The study focuses on the 3D RANS solutions of a water boundary layer pump model created to replicate a design which consists of 170 discs and a volute channel. A baseline study is performed to investigate the rotor-only and volute-only flow fields and identify the losses in each as separate systems. Thereafter, an integrated model is characterized for different operating conditions. The flow fields of all three models are discussed and the results of the integrated model are compared to the experimental data. The results from the rotor-only model confirm the typically made claim that the rotor efficiency is relatively high, which in this case is 87% at the design point. The volute on its own indicated a hydraulic efficiency of ~97%. However, the integrated model yielded a rotor efficiency of ~74% and an overall pump efficiency of 51% at the design point, clearly outlining the fact that the effect of the volute integrated with the rotor is the reason for both the rotor and pump efficiency degradation. The reason for this drop in efficiency is discussed by highlighting the change in the flow topologies. The insights into the flow field and the identification of the reason for inefficiencies using a separated component analysis approach provides directions for avenues in which design improvements need to be attempted.Item Open Access Mechanical design and manufacture of a boundary layer pump(EDP Sciences, 2023-08-25) Bufalari, Lapo; Anselmi, Eduardo; Rinchi, Mirko; Howard, Kevin; Talluri, Lorenzo; Fiaschi, DanieleThis paper describes the current efforts to develop and manufacture a first prototype for a boundary layer pump as a mean to assess future and more complex designs. Following an approach of “learning by doing”, a previous design was re-assessed from a mechanical/workshop point of view. Budget constraints and in-house manufacturing capabilities were taken into consideration to deliver a new design, suitable for quick production. Challenges such as disc holding, gap spacing, pump intake, discharge nozzles, and tolerances were addressed. Structural analysis has been conducted; where every single component has been modelled and sized accordingly to standard practices. As a support of structural analysis, FEM analysis was also performed with the aim of identifying, discussing, and fixing any potentially critical issues, particularly regarding the bolts holding together the discs into the power shaft. Finally, modal analysis was performed in order to test the dynamic response of the rotor: its critical frequencies would be far from the working range of the machine. This paper gives an overview of the critical issues to be taken into account during the mechanical design of boundary layer pump prototypes for different working fluids in the field of power generation and thermal management.Item Open Access An overview of the Rolls-Royce sCO2-test rig project at Cranfield University(Southwest Research Institute, 2018-04-08) Anselmi, Eduardo; Bunce, Ian; Pachidis, Vassilios; Zachos, Pavlos; Johnston, MichaelAn experimental facility is currently under development at Cranfield University, aiming to explore supercritical carbon dioxide as a working fluid for future bottoming power cycle applications for Rolls- Royce. The initial objectives of this experimental program are to de-risk and demonstrate the robustness of a closed loop system, as well as to prove the function and performance of individual components and various measurement and control modules. This paper describes the planning and development phases of the test facility and summarises the lessons learnt from the component specification and component interface processes.Item Open Access Parametric evaluation of S-CO2 Brayton cycles for bottoming applications(2016-10-11) Brighenti, Giovanni; Anselmi, Eduardo; Zachos, PavlosParametric design studies for the preliminary assessment of physical footprint of Supercritical CO2 power plants are presented herein. The aim of the study is to quantify trade-offs between cycle efficiency and plant complexity for a range of S-CO2 cycle configurations.Item Open Access Update of the sCO2-test rig at Cranfield University(American Society of Mechanical Engineers, 2022-10-28) Anselmi, Eduardo; Belleoud, Pierre; Roumeliotis, Ioannis; Pachidis, VassiliosSince 2018, there is an experimental supercritical carbon dioxide (sCO2) facility operating at Cranfield University. The purpose of this rig is to enable the exploration of supercritical carbon dioxide as a working fluid for future bottoming power cycle applications and, more recently, for thermal management applications. The core of the rig is a transcritical closed loop, which has recently been upgraded. The upgrades include an increase in the number of measurement stations, changes to the types of measurements taken, as well as the addition of a new, dedicated data acquisition system. A summary of some of the lessons learned from different test campaigns conducted from 2018 to 2021 is provided, along with a discussion on the measurement upgrades performed. The experience obtained with this rig, as recounted in this paper, could be relevant to similar test rigs or future power cycles applications.