A physics-based turbocharger model for automotive diesel engine control applications

Abstract

Control-oriented models of turbocharger processes such as the compressor mass flow rate, the compressor power, and the variable geometry turbine power are presented. In a departure from approaches that rely on ad hoc empirical relationships and/or supplier provided performance maps, models based on turbomachinery physics and known geometries are attempted. The compressor power model is developed using Euler’s equations of turbomachinery, where the gas velocity exiting the rotor is estimated from an empirically identified correlation for the ratio between the radial and tangential components of the gas velocity. The compressor mass flow rate is modeled based on mass conservation, by approximating the compressor as an adiabatic converging-diverging nozzle with compressible fluid driven by external work input from the compressor wheel. The variable geometry turbine power is developed with Euler’s equations, where the turbine exit swirl and the gas acceleration in the vaneless space are neglected. The gas flow direction into the turbine rotor is assumed to align with the orientation of the variable geometry turbine vane. The gas exit velocity is calculated, similar to the compressor, based on an empirical model for the ratio between the turbine rotor inlet and exit velocities. A power loss model is also proposed that allows proper accounting of power transfer between the turbine and compressor. Model validation against experimental data is presented.

Applicable and Comparative Research of Compressor Mass Flow Rate and Isentropic Efficiency Empirical Models to Marine Large-Scale Compressor

“…In the surging zone, the momentum of airflow cannot stably overcome the adverse pressure gradient across the compressor, and reverse To cover different operating environments, corrected quantities including the corrected rotational speed N corr and corrected mass flow rate . m corr are usually utilized in the performance map with their definitions as follows N corr = N 1 T in /T ref (1) .…”

“…where T ref and p ref are the reference temperature and pressure, respectively, T in and p in are the temperature and pressure at the compressor inlet, respectively. The derivation of Equations (1) and (2) is based on the dimensional analysis of the compression process in a compressor [14]. For a compressor, its whole operating area is normally divided into three zones, as shown in Figure 1, i.e., design operating zone, surging zone, and choking zone.…”

“…In the field of automotive engines, several new types of turbocharging systems have emerged, such as electrically assisted turbocharging systems (E-Turbo), variable geometry turbochargers (VGTs), and variable geometry compressors (VGCs). It was revealed by many pieces of research that, compared with traditional turbocharging technology, these advanced technologies can not only effectively improve turbocharger performance at low loading conditions but also substantially extend the operating range [1,2]. Nowadays, large marine two-stroke diesel engines are generally equipped with a turbocharging system but they still lag behind automotive engines to some extent.…”

A new method for performance map prediction of automotive turbocharger compressors with both vaneless and vaned diffusers

“…Hence, the engine size could be considerably decreased, the fuel consumption and gas emission might also be reduced. [1][2][3][4] The centrifugal compressor is a key component of a turbocharger, its aerodynamic performance greatly affects the operation of the turbocharged internal combustion engine. Knowing the compressor performance map exactly will benefit the matching process between the turbocharger and the internal combustion engine.…”