Influence of Upstream Exhaust Manifold on Pulsatile Turbocharger Turbine Performance

Abstract

This research was primary motivated by limited efforts to understand the effects of secondary flow and flow unsteadiness on the heat transfer and the performance of a turbocharger turbine subjected to pulsatile flow. In this study, we aimed to investigate the influence of exhaust manifold on the flow physics and the performance of its downstream components, including the effects on heat transfer, under engine-like pulsatile flow conditions. Based on the predicted results by detached eddy simulation (DES), qualitative and quantitative flow fields analyses in the scroll and the rotor's inlet were performed, in addition to the quantification of turbine performance by using the flow exergy methodology. With the specified geometry configuration and exhaust valve strategy, our study showed that (1) the exhaust manifold influences the flow field and the heat transfer in the scroll significantly and (2) although the exhaust gas blow-down disturbs the relative flow angle at rotor inlet, the consequence on the turbine power is relatively small.

Turbocharger Radial Turbine Response to Pulse Amplitude

“…Yang et al [44] linked the instantaneous absolute inflow angle to the time derivative of the ratio between static pressure and temperature, besides the geometric parameters of the volute. Lim et al [23] reported the exhaust manifold to have a direct effect on the inflow angle, as responsible for the secondary flows inside the volute.…”

“…1, consists of a single scroll and 12 blades turbine applied in a 2.0 L and four-cylinder engine passenger car. As the flow field inside the volute is largely affected by the system of the upstream bent pipes [23], the exhaust manifold is included in the model in order to replicate real on-engine conditions. Downstream to the turbine, the diffuser is followed by a convergent duct (not shown in Fig.…”

“…The reader is referred to the existing literature for the application of the below-mentioned flow exergy methodology in turbomachinery applications (e.g., see Refs. [9,23,32]).…”

Numerical Analysis of Engine Exhaust Flow Parameters for Resolving Pre-Turbine Pulsating Flow Enthalpy and Exergy

“…Based on the flow thermal energy conversion ratios, the design of a heat exchanger was improved for better waste heat recovery [3]. In particular, many turbocharger studies focused on the utilization of energy carried by ICE pulsating flows, such as the impacts of different unsteady inlet conditions [4][5][6] along with reducing the thermal dissipation of exhaust pulses upstream of the turbine [7][8][9] and optimizing the configurations of turbocharging systems [10,11], to name a few.…”

“…For the studies regarding time-varying flow parameters of exhaust pulsation, due to the challenges and limitations of on-engine time-resolved exhaust gas flow parameter measurement, assessment of instantaneous exhaust energy in literature often seeks assistance from simulations [6,17]. Apart from piezoresistive fast pressure sensors which are well established and widely used in ICE research [21], many previous studies attempted to capture the time-varying flow temperature and velocity (or mass flow rate) of exhaust pulsating flows.…”