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Research Papers

# Unsteady Performance of a Double Entry Turbocharger Turbine With a Comparison to Steady Flow Conditions

[+] Author and Article Information
Colin D. Copeland

Department of Mechanical Engineering, Imperial College London, London SW7 2AZ, United Kingdomc.copeland@imperial.ac.uk

Ricardo Martinez-Botas1

Department of Mechanical Engineering, Imperial College London, London SW7 2AZ, United Kingdomr.botas@imperial.ac.uk

Martin Seiler

ABB Turbo Systems Limited, Baden CH-5401, Switzerlandmartin.a.seiler@ch.abb.com

1

Corresponding author.

J. Turbomach 134(2), 021022 (Jun 30, 2011) (10 pages) doi:10.1115/1.4003171 History: Received February 16, 2009; Revised March 24, 2009; Published June 30, 2011; Online June 30, 2011

## Abstract

Circumferentially divided, double entry turbocharger turbines are designed with a dividing wall parallel to the machine axis such that each entry feeds a separate 180 deg section of the nozzle circumference prior to entry into the rotor. This allows the exhaust pulses originating from the internal combustion exhaust to be preserved. Since the turbine is fed by two separate unsteady flows, the phase difference between the exhaust pulses entering the turbine rotor will produce a momentary imbalance in the flow conditions around the periphery of the turbine rotor. This research seeks to provide new insight into the impact of unsteadiness on turbine performance. The discrepancy between the pulsed flow behavior and that predicted by a typical steady flow performance map is a central issue considered in this work. In order to assess the performance deficit attributable to unequal admission, the steady flow conditions introduced in one inlet were varied with respect to the other. The results from these tests were then compared with unsteady, in-phase and out-of-phase pulsed flows most representative of the actual engine operating condition.

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## Figures

Figure 1

Circumferentially divided, double-entry turbocharger turbine

Figure 2

Test facility layout

Figure 3

Steady, equal admission relative efficiency versus velocity ratio for different constant speed lines

Figure 4

Steady, equal admission relative mass parameter versus pressure ratio for different constant speed lines

Figure 5

Performance of the turbine operating with unequal, steady flows as a percentage of peak, equal admission efficiency. Plotted against the inlet ratio of pressures.

Figure 6

Unequal, isentropic flow area relative to the equal admission flow area. Plotted against the inlet ratio of pressures.

Figure 7

Out-of-phase and in-phase absolute pressure pulses prior to nozzle (100% speed)

Figure 8

Figure 9

3D plot of steady equal and unequal relative efficiencies

Figure 10

Figure 11

Figure 12

Figure 13

Figure 14

In-phase, unsteady mass parameter versus pressure ratio: (a) 50%, 33 Hz, (b) 70%, 46 Hz, and (c) 100%, 66 Hz

Figure 15

Out-of-phase, unsteady mass parameter versus pressure ratio: (a) 50%, 33 Hz, (b) 70%, 46 Hz, and (c) 100%, 66 Hz

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