Experimental approach for the analysis of the flow behaviour in the stator of a real centripetal turbine

Abstract

During normal operation, radial turbines may work in off-design conditions. Off-design conditions may be characterised by very low expansion ratios, very high expansion ratios, very low rotational speeds or very high rotational speeds. All of these cases are difficult to characterise experimentally due to high experimental uncertainties or a lack of capabilities in the system feeding pressurised air to the turbine. Also, there are two- and three-dimensional computational fluid dynamics simulations at these operating points but could not be accurate enough due to high turbulence effects, flow detachment and shock wave generation. With a lack of high-quality data, experimental or computational, to fit the reduced-order turbine models used in zero- and one-dimensional engine simulations, there are large uncertainties associated to their results in off-design conditions. This work develops an experimental facility able to characterise the internal flow of radial turbine stators in terms of pressure and velocity fields at off-design and regular working conditions. The facility consists of an upscaled model of a radial turbine volute and stator fed with air in pressure- and temperature-controlled conditions, so different sensors can be used inside it with the least amount of flow disturbance. The different restrictions considered in the design of the upscaled model are presented, and their effects in the final experimental apparatus capabilities are discussed. A preliminary comparison between computational fluid dynamics simulations and experimental data shows encouraging results.

A novel variable geometry turbine achieved by elastically restrained nozzle guide vanes. Part II: Experimental evaluation

“…On the performance of turbocharger turbines, including the steadystate and unsteady-state performance, scholars around the world have conducted many related studies. [11][12][13] In the traditional VGT performance experiments, the turbine performance can be described by superimposing characteristics measured at various fixed inlet guide vane (IGV). 14 In contrast, the ERGV turbine performance test is different, which does not need to fix the IGV due to the adaptive rotation of the guide vane.…”

Experimental approach of surface pressure measurements on additive manufactured nozzle guide vane in a turbocharger turbine

“…7 Srithar Rajoo 8 discussed the details of unsteady experimentation and analyzed of a twin-entry variable geometry turbine for an automotive turbocharger. Jose Galindo 9 developed an experimental facility able to characterize the internal flow of radial turbine stators in terms of pressure and velocity fields at off-design and regular working conditions. A. Romagnoli 10 tested a twin-entry turbine under partial and unequal admissions.…”

Numerical Analysis of the Effects of Different Rotor Tip Gaps in a Radial Turbine Operating at High Pressure Ratios Reaching Choked Flow

“…Over the last few years, with the improvement of computational tools and experimental measuring techniques, different studies have been carried out to characterize the internal flow behavior of the radial turbine as the flow goes through its components such as the volute, stator, and rotor. However, since radial turbine geometry is quite compact and relatively small, especially in urban automotive engines, the installation of sensors in each of the aforementioned elements is quite limited [14] and in some cases it is necessary to scale the geometry [15,16] to measure the pressure and velocity inside the stator [17]. Furthermore, the complex three-dimensional flow structure occurring in the stage turbine cannot be completely modeled by the one-dimensional approach available in the literature [18].…”