A gas generator—consisting of a single-stage shrouded mixed-flow compressor without a diffusor, a rotating combustion chamber, and a vaneless single-stage shrouded centripetal turbine—is presented and analyzed here. All components comprise a coherent rotating device, which avoids most of the problems usually associated with small gas generators. In other words, the concept avoids all radial clearances; it is vaneless, shortens the combustion chamber, minimizes the wetted area, and enables ceramic materials to be used, due to compressive blade stresses. However, the concept faces severe structural, thermal, and chemical reaction challenges and is associated with a large Rayleigh-type total pressure loss. All these features and their implications are discussed and their benefits and drawbacks for several jet engines are quantified, mainly by means of thermodynamic cycle calculations. As a result, it has been demonstrated that the concept offers a thrust-to-weight ratio which is higher than the standard when incorporated into small unmanned aerial vehicles (UAV)-type jet engines. It also enables an attractive multistage and dual-flow, but fully vaneless design option. However, the concept leads to a decrease in thermal efficiency if these were to be accomplished in the (small) core of turbofans with highest overall pressure ratios (OPRs) and high bypass ratios. In summary, the paper presents a gas generator approach, which may be considered by designers of small jet engines with high power density requirements, like those used in UAV applications. But this has been proven not to be an option for high-efficiency propulsion.

References

1.
TEAL Group, Corporation
,
2008
, “
Market Profile and Forecast
,”
World Unmanned Aerial Vehicle Systems
,
TEAL Group
, Fairfax, VA.
2.
Denis
,
L. D. H.
, and
Serruys
,
M. Y. A.
,
1959
, “
Gas Turbine Plant Acting as Generator of Gas Under Pressure
,” Patent No. GB 818,063.
3.
Campbell
,
G. K. C.
,
1971
, “
Gas Turbine Engine With Rotating Combustion Chamber
,” U.S. Patent No. 3,557,551.
4.
Lawlor
,
S. P.
,
Steele
,
R. C.
, and
Kendrick
,
D.
,
2004
, “
Rotary Ramjet Engine With Flameholder Extending to Running Clearance at Engine Casing Interior Wall
,” U.S. Patent No. 6,694,743 B2.
5.
Lior
,
D.
,
2008
, “
Orbiting Combustion Nozzle Engine
,” U.S. Patent No. 7,404,286 B2.
6.
Chamis
,
C. C.
, and
Blankson
,
I. M.
,
2003
, “
Exo-Skeletal Engine—Novel Engine Concept
,”
ASME
Paper No. GT2003-38204.10.1115/GT2003-38204
7.
Halliwell
,
I.
,
2001
, “
Exoskeletal Engine Concept: Feasibility Studies for Medium and Small Thrust Engines
,” NASA Modern Technologies Corporation, Technical Report No. NASA/CR-2001-211322.
8.
Lewis
,
G. D.
,
1973
, “
Centrifugal-Force Effects on Combustion
,”
Symp. (Int.) Combust.
,
14
(
1
), pp.
413
419
.10.1016/S0082-0784(73)80040-2
9.
Klemm
,
H.
,
2010
, “
Silicon Nitride for High-Temperature Applications
,”
J. Am. Ceram. Soc.
,
93
(
6
), pp.
1501
1522
.10.1111/j.1551-2916.2010.03839.x
10.
Lapsa
,
A. P.
, and
Dahm
,
W. J.
,
2009
, “
Hyperacceleration Effects on Turbulent Combustion in Premixed Step-Stabilized Flames
,”
Proc. Combust. Inst.
,
32
(
2
), pp.
1731
1738
.10.1016/j.proci.2008.05.038
11.
Zelina
,
J.
,
Shouse
,
D. T.
, and
Hancock
,
R. D.
,
2004
, “
Ultra-Compact Combustors for Advanced Gas Turbine Engines
,”
ASME
Paper No. GT2004-53155.10.1115/GT2004-53155
12.
Zelina
,
J.
,
Greenwood
,
R. T.
, and
Shouse
,
D. T.
,
2006
, “
Operability and Efficiency Performance of Ultra-Compact, High Gravity (g) Combustor Concepts
,”
ASME
Paper No. GT2006-90119.10.1115/GT2006-90119
13.
Zelina
,
J.
,
Shouse
,
D. T.
,
Stutrud
,
J. S.
,
Sturgess
,
G. J.
, and
Roquemore
,
W. M.
,
2006
, “
Exploration of Compact Combustors for Reheat Cycle Aero Engine Applications
,”
ASME
Paper No. GT2006-90179.10.1115/GT2006-90179
14.
Zelina
,
J.
,
Anderson
,
W.
,
Koch
,
P.
, and
Shouse
,
D. T.
,
2008
, “
Compact Combustion Systems Using a Combination of Trapped Vortex and High-G Combustor Technologies
,”
ASME
Paper No. GT2008-50090.10.1115/GT2008-50090
15.
Picard
,
M.
,
Rancourt
,
D.
, and
Plante
,
J.-S.
,
2011
, “
Rim-Rotor Rotary Ramjet Engine (R4E): Design and Experimental Validation of a Proof-of-Concept Prototype
,”
ISABE Conference
, Gothenburg, Sweden, Sept. 12–16, Paper No. ISABE2011-1258.
16.
Spytek
,
C. J.
,
2012
, “
Application of an Inter-Turbine Burner Using Core Driven Vitiated Air in a Gas Turbine Engine
,”
ASME
Paper No. GT2012-69333.10.1115/T2012-69333
17.
Menter
,
F. R.
,
1994
, “
Two-Equation Eddy-Viscosity Turbulence Models for Engineering Applications
,”
AIAA J.
,
32
(
8
), pp.
1598
1605
.10.2514/3.12149
18.
Ziegler
,
K. U.
,
2003
, “
Experimentelle Untersuchung der Laufrad-Diffusor-Interaktion in Einem Radialverdichter Variabler Geometrie
,” dissertation, RWTH Aachen, D 82 Shaker Verlag, Aachen, Germany.
19.
Smirnov
,
P. E.
,
Hansen
,
T.
, and
Menter
,
F. R.
,
2007
, “
Numerical Simulation of Turbulent Flows in Centrifugal Compressor Stages With Different Radial Gaps
,”
ASME
Paper No. GT2007-27376.10.1115/GT2007-27376
20.
Kurzke
,
J.
,
2012
, “
GasTurb—The Gas Turbine Performance Simulation Program
,” GasTurb GmbH, Aachen, Germany, www.gasturb.de
21.
Penkner
,
A.
, and
Jeschke
,
P.
,
2014
, “
Analytic Rayleigh Pressure Loss Model for High-Swirl Combustion in a Rotating Combustion Chamber
,” 63rd Deutscher Luft- und Raumfahrtkongress: Augsburg, Germany, Sept. 16–18, Paper No. DLRK–2014–340267.
22.
UAS
,
2009
,
The Global Perspective
, 7th ed.,
Blyenberg & Co
, Paris.
23.
Fullagar
,
K. P. L.
,
1974
, “
The Design of Air Cooled Turbine Rotor Blades
,” British Aeronautical Research Council, London, UK, Report 35684, Report No. HMT 361.
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