The flow of opposing jets was studied in computational fluid
dynamics simulation. To clarify the flow field of the jet engine
combustor, it is necessary to study air-jet dilution effects typical of
opposing jets. The velocity distribution and turbulence intensity
were obtained in large eddy simulation for air and an average
Reynolds number of 2 × 104 corresponding to the jet diameter and
velocity. Results obtained numerically generally agreed
quantitatively with experimental results obtained in our previous
study. Simulations were then carried out to clarify the effect of the
momentum flux ratio J (4, 9, 16, and 64) on mixing. Unmixedness
was found to be highest for J = 4 since the penetrations and thus
collision of opposing jets were weak for J = 4. When J = 9, 16, 64,
mixing was improved by jet collision. It is proposed that the mixing
mechanisms are differed depending on J.
In order to achieve high process efficiencies for the economic
operation of stationary gas turbines and aero engines, extremely
high turbine inlet temperatures at adjusted pressure ratios are
applied. The allowable hot gas temperature is limited by the
material temperature of the hot gas path components, in particular
the vanes and blades of the turbine. Thus, intensive cooling is
required to guarantee an acceptable life span of these components.
Modern computational tools as well as advanced calculation
methods support essentially on the successful design of these
thermally high-loaded components. The homogeneous, or
sometimes also mentioned as “full”, conjugate calculation
technique for the coupled calculation of fluid flows, heat transfer
and heat conduction is such an advanced numerical approach in the
design process and huge experiences on validation and application
have been collected throughout the years. This paper summarizes
the numerical approach for this method as well as provides a
collection of numerical results obtained by the authors for
validation cases for a convection-cooled turbine vane test case as
well as comparison to calculation data for this test case provided in
open literature. Furthermore, systematic studies on the impact of
calculation parameters, e.g. hot gas fluid properties, and numerical
models for turbulence calculation are performed and the numerical
results are compared to the experimental results of the test case.
The thermodynamic cycle of an intercooled turbofan engine was optimized
by considering various characteristics of intercoolers (ICs).
Sixty-three intercooled turbofan engines were optimized using an
evolutionary algorithm. Thirty-nine design parameters were analyzed
using proper orthogonal decomposition, and the effects of the
IC performance on the engine thermodynamic cycle were examined.
The improvement in net fuel consumption due to intercooling
strongly depends on the characteristics of the IC fin, and the
net fuel consumption is minimized at a particular fin height. By
using ICs with an appropriate fin height, intercooling increases the
overall pressure ratio, while increasing the heat transfer surface areas
and cross-sectional areas of the ICs realizes high effectiveness
and low pressure losses. The pressure ratio partition between the
intermediate- and high-pressure compressors is determined according
to incompatible characteristics of the IC, such as pressure losses
and the temperature difference between the inlet and outlet of the
IC. Because the weight of the IC is proportional to its fin area density,
increasing the fin area density reduces the net fuel consumption.
However, it does not significantly influence the thermodynamic cycle
of the engine.