Experimental assessment of the rotor outlet flow in a twin-entry radial turbine by means of Laser Doppler Anemometry

Abstract

The current paper presents the validation of some hypotheses used for developing a one-dimensional twin-entry turbine model with experimental measurements. A Laser Doppler Anemometry (LDA) technique has been used for measuring the axial Mach number and for counting the number of particles downstream of the rotor outlet. These measurements have been done for different mass flow ratio (MFR) and reduced turbocharger speed conditions. The flow coming from each turbine entry does not fully mix with the other within the rotor since, downstream of the rotor, they can still be differentiated. Thus, the hypothesis of studying twin-entry turbines as two separated single-entry turbines in one-dimensional models is corroborated. Moreover, the rotor outlet area corresponding to each flow branch has linear trends with the MFR value. Therefore, the rotor outlet effective area used for one-dimensional models should vary linearly with the MFR value.

Flow Capacity and Efficiency Modelling of Twin-Entry Radial Turbines under Unequal Admission Conditions through CFD Analysis and Experiments

“…• "Experimental assessment of the rotor outlet flow in a twin-entry radial turbine by means of Laser Doppler Anemometry", in International Journal of Engine Research (2021) by Galindo, Tiseira, García-Cuevas and Medina [4].…”

“…2. 4. It is defined as the ratio between the turbine power W ̇turb and the turbine isentropic power W ̇turb,is .…”

“…CMT-Motores Térmicos also has a twin-entry turbine gas stand specially prepared to control the mass flow and pressure conditions of each branch sep-2. 4. CFD characterisation and modelling arately, as described in Serrano et al [49].…”

“…Moreover, the figure is divided in two plots with the measurements of each flow branch for 3. 4 The flow capacity map shows that increasing the reduced rotational speed means increasing the expansion ratio. This behaviour was expected since the rotational speed was fixed experimentally, varying the total inlet pressure.…”

“…Thus, all necessary parts have been digitalised, whether directly or from silicone moulds, and prepared to use in CFD software, as shown in Fig. 4 The CFD domain has been sub-divided into different parts to mesh it properly. All meshes are non-structured polyhedral meshes.…”