Browsing by Author "Anselmi Palma, Eduardo"
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Item Open Access Flow field explorations in a boundary layer pump rotor for improving 1D design codes(MDPI, 2023-02-03) Freschi, Rosa; Bakogianni, Agapi; Rajendran, David John; Anselmi Palma, Eduardo; Talluri, Lorenzo; Roumeliotis, IoannisBoundary layer pumps, although attractive due to their compactness, robustness and multi-fluid and phase-handling capability, have been reported to have low experimental efficiencies despite optimistic predictions from analytical models. A lower-order flow-physics-based analytical model that can be used as a 1D design code for sizing and predicting pump performance is described. The rotor component is modelled by means of the Navier–Stokes equations as simplified using velocity profiles in the inter-disk gap, while the volute is modelled using kinetic-energy-based coefficients inspired by centrifugal pumps. The code can predict the rotor outlet and overall pump pressure ratio with an around 3% and 10% average error, respectively, compared to the reference experimental data for a water pump. Moreover, 3D RANS flow-field explorations of the rotor are carried out for different inter-disk gaps to provide insights concerning the improvement of the 1D design code for the better prediction of the overall pump performance. Improvements in volute loss modelling through the inclusion of realistic flow properties at the rotor outlet rather than the detailed resolution of the velocity profiles within the rotor are suggested as guidelines for improved predictions. Such improved design codes could close the gap between predictions and experimental values, thereby paving the way for the appropriate sizing of boundary layer pumps for several applications, including aircraft thermal management.Item Open Access Performance comparison of temperature sensors for closed cycles operating with supercritical CO2(Unclear, 2023-03-16) Belleoud, Pierre; Anselmi Palma, Eduardo; Chetwynd-Chatwin, Jason; Roumeliotis, IoannisNear the critical point of carbon dioxide (CO2), small changes in temperature or pressure can result in large changes in the calculation of its thermodynamic properties, thus the right choice of instrumentation is of importance. This paper addresses the challenges related to CO2 temperature measurement in smalldiameter pipes and assesses different sensors utilizing Cranfield University’s supercritical CO2 test rig capabilities. In order to compare temperature sensor types for supercritical CO2, a test tube has been designed to fit different sizes of temperature probes at the discharge of the transcritical compressors at the sCO2 test rig. Different diameters of thermocouples (0.75 to 4.5 mm), Resistance Temperature Detectors (RTDs) and surface sensors were tested and compared in terms of amplitude and adaptability to sudden temperature changes. Results for different fluid conditions in the supercritical region of CO2 were derived. The use of thermowell is discussed as it can offer a suitable compromise between practicality and ‘internal’ measurements. The results presented in this paper aim to provide a comparison of temperature sensors’ performances for different regimes, transient or steady state.