Variable geometry turbine (VGT) has been widely applied in internal combustion engines to improve engine transient response and torque at light load. One of the most popular VGTs is the variable nozzle turbine (VNT) in which the nozzle vanes can be rotated along the pivoting axis and thus the flow passage through the nozzle can be adjusted to match with different engine operating conditions. One disadvantage of the VNT is the turbine efficiency degradation due to the leakage flow in the nozzle endwall clearance, especially at small nozzle open condition. With the purpose to reduce the nozzle leakage flow and to improve turbine stage efficiency, a novel split sliding variable nozzle turbine (SSVNT) has been proposed. In the SSVNT design, the nozzle is divided into two parts: one part is fixed and the other part can move along the partition surface. When sliding the moving vane to large radius position, the nozzle flow passage opens up and the turbine has high flow capacity. When sliding the moving vane to small radius position, the nozzle flow passage closes down and the turbine has low flow capacity. As the fixed vane does not need endwall clearance, the leakage flow through the nozzle can be reduced. Based on calibrated numerical simulation, there is up to 12% turbine stage efficiency improvement with the SSVNT design at small nozzle open condition while maintaining the same performance at large nozzle open condition. The mechanism of efficiency improvement in the SSVNT design has been discussed.

References

References
1.
Bains
,
N.
,
1998
, “
Radial and Mixed Flow Turbines Options for High Boost Turbocharger
,”
Seventh International Conference on Turbocharger and Turbocharging
, pp.
35
44
.
2.
Watson
,
N.
, and
Janota
,
M.
,
1982
,
Turbocharging the Internal Combustion Engine
,
Macmillan Education
,
New York
.
3.
Rogo
,
C.
,
Hajek
,
T.
, and
Relke
,
R.
, 1983, “Aerodynamic Effects of Moveable Sidewall Nozzle Geometry and Rotor Exit Restriction on the Performance of a Radial Turbine,”
SAE
Paper No. 831517.
4.
Arnold
,
S.
, 1987, “Schwitzer Variable Geometry Turbo and Microprocessor Control Design and Evaluation,”
SAE
Paper No. 870296.
5.
Franklin
,
P.
, 1989, “Performance Development of the Holset Variable Geometry Turbocharger,”
SAE
Paper No. 890646.
6.
Kawaguchi
,
J.
,
Adachi
,
J.
, and
Kono
,
S.
, 1999, “Development of VFT (Variable Flow Turbocharger),”
SAE
Paper No. 1999-01-1242.
7.
Hayami
,
H.
,
Senoo
,
Y.
, and
Hyun
,
Y.
,
1990
, “
Effects of Tip Clearance of Nozzle Vanes on Performance of Radial Turbine Rotor
,”
ASME J. Turbomach.
,
112
(
1
), pp.
58
63
.
8.
Tamaki
,
H.
,
Goto
,
S.
, and
Unno
,
M.
, 2010, “The Effect of Clearance Flow of Variable Area Nozzles on Radial Turbine Performance,”
ASME
Paper No. GT2010-23677.
9.
Hu
,
L.
,
Yang
,
C.
, and
Sun
,
H.
,
2011
, “
Numerical Analysis of Nozzle Clearance Effect on Turbine Performance
,”
Chin. J. Mech. Eng.
,
24
(
4
), pp.
618
625
.
10.
Walkingshaw
,
J.
,
Spence
,
S.
, and
Enrhard
,
J.
,
2012
, “
An Experimental Assessment of the Effects of Stator Vane Tip Clearance Location and Back Swept Blading on an Automotive Variable Geometry Turbocharger
,”
ASME J. Turbomach.
,
226
(
6
), pp.
751
763
.
11.
Tomoki
,
K.
,
Goto, S.
,
Unno, M.
, and
Iwakami, A.
,
2008
, “Unsteady Rotor-Stator Interaction of a Radial-Inflow Turbine With Variable Nozzle Vanes,”
ASME
Paper No. GT2008-50461.
12.
Hu
,
L.
,
Sun
,
H.
,
Yi
,
J.
,
Curtis, E.
,
Morelli, A.
,
Zhang, J.
,
Zhao, B.
,
Yang, C.
,
Shi, X.
, and
Liu, S.
, 2013, “Investigation of Nozzle Clearance Effects on a Radial Turbine: Aerodynamic Performance and Forced Response,”
SAE
Paper No. 2013-01-0918.
13.
Sun
,
H.
,
Zhang
,
J.
, and
Hu
,
L.
, 2013, “Sliding Vane Geometry Turbine,” Ford Global Technologies, LLC, Dearborn, MI, U.S. Patent No.
US20130042608 A1
.
14.
NUMECA
,
2014
,
IGG User Manual
,
v9, ed.
,
NUMECA International
,
Brussels, Belgium
.
15.
Zhu
,
D.
,
1992
,
Turbocharging and Turbochargers
,
China Machine Press
,
Beijing, China
.
16.
He
,
P.
,
Sun, Z. G.
,
Chen
,
H. S.
, and
Tan, C. Q.
,
2012
, “
Investigation of Backface Cavity Sealing Flow in Deeply Scalloped Radial Turbines
,”
Proc. Inst. Mech. Eng. Part A
,
226
(6), pp. 751–763.
17.
Bains
,
N.
,
2005
,
Fundamentals of Turbocharging
,
Concepts NREC
, White River Junction,
VT
.
18.
Arnold
,
S.
,
Groskrevtz
,
M.
, and
Shahed
,
S.
, 2002, “Advanced Variable Geometry Turbocharger for Diesel Engine Applications,”
SAE
Paper No. 2002-01-0161.
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