The work presents the
results of an analysis of starting conditions for some frontal axisymmetric
inlets of internal compression tested at
freestream Mach numbers М = 3-8.4 in the hot-shot wind tunnels based at Khristianovich Institute of Theoretical and Applied Mechanics (ITAM). The results of these inlets test are
compared with the data of numerical computations of inviscid, laminar,
and turbulent flows carried out by the pseudo-unsteady method. There were
determined the inlet throat areas limiting either with regard to the inlet
starting or with regard to providing the maximally possible degree of
geometric compression of the inlet-captured supersonic airstream at its
deceleration in the already started inlet. Reshaping of computed flow
patterns in the inlets depending on the variation of the mini-mal cross section
of the inlet internal duct is analyzed.
A criterion was
elaborated for the phenomenon of dry spot evolution in isothermal liquid films
on a horizontal substrate. The formulas are presented for gravity force and
surface tension acting upon an element of the rim around the dry spot. The
forces balance gives the evolution of initial dry spot: to expand or to
contract.
Within the framework of
approximate physical and mathematical model, we considered the stationary
problem of propagation of evaporation front in superheated liquid along the
flat heater. The analytical dependence of the vapor layer thickness on the
coordinate and physical parameters has been obtained. The solution is presented
in invariant dimensionless form. Satisfactory agreement between theoretical
results and new experimental data is shown.
The method has been developed to calculate infrared radiation of vibrational nonequilibrium gas based on k-distribution. A comparison
of the data on the calculated nonequilibrium radiation with results of other
authors and with experimental data has shown satisfactory agreement. It is
shown that the results of calculation of radiation intensity using
nonequilibrium and equilibrium methods significantly differ from each other.
The discrepancy increases with increasing height (decreasing pressure) and can
exceed an order of magnitude.
The
results of the numerical and experimental investigations of the evolution of
the disturbances in a hypersonic shock layer on a flat plate streamlined by a
flow of the mixture of vibrationally excited gases are presented.
The experimental study was conducted in the hot-shot high-enthalpy wind
tunnel IT-302 of the ITAM SB RAS. The numerical simulation was carried out
with the aid of the ANSYS Fluent package using the solution of the unsteady
two-dimensional Navier-Stokes equations with the incorporation of the
user-created modules and enabling the con-sideration of the vibrational
non-equilibrium of the carbon dioxide molecules within the framework of the
model of the two-temperature aerodynamics. It was obtained that an
increase in the carbon dioxide concentration in the mixture with air leads to a
reduction of the intensity of pressure disturbances on the surface. The
efficiency (up to 20 %) of the method of sound absorbing coatings in
the vibrationally excited flows of the mixture of the carbon dioxide and air
has been shown.
Results of a
numerical study of performance characteristics of supersonic ejectors with
nozzles of different types are reported. The work was carried out with the aim
of developing a high-performance ejector for pressure recovery systems of
supersonic chemical lasers. A specific feature of the operation of ejectors in
pressure recovery systems consists in that, in this case, the ejecting and
ejected gases, as they undergo mixing, have different thermodynamic
properties, and the ejection coefficient depends on the ratio between the
temperatures of the gases and on the ratio of their molecular masses. Since the
operation of an ejector is based on the mixing process, the task consisted in
intensification of this process using nozzles of special geometries. The
performance of ejectors was judged considering an integral parameter, the product of induction by compression ratio. The
calculations of the 3D viscous gas flow in the ejector channel were
performed using ANSYS software. In verifying the numerical model, a comparison
with experimental data obtained earlier on a model ejector facility and during
tests of real pressure recovery systems in operation with supersonic chemical
lasers was performed.
A class of flowing
medium gas lasers with low generator pressures employ supersonic flows with low
cavity pressure and are primarily categorized as high throughput systems
capable of being scaled up to MW class. These include; Chemical Oxygen Iodine
Laser (COIL) and Hydrogen (Deuterium) Fluoride (HF/DF). The practicability of
such laser systems for various applications is enhanced by exhausting the effluents
directly to ambient atmosphere. Consequently, ejector based pressure recovery
forms a potent configuration for open cycle operation. Conventionally these gas
laser systems require at least two ejector stages with low pressure stage being
more critical, since it directly entrains the laser media, and the ensuing
perturbation of cavity flow, if any, may affect laser operation. Hence,
the choice of plausible motive gas injection schemes viz., peripheral or
central is a fluid dynamic issue of interest, and a parametric
experimental performance comparison would be beneficial. Thus, the focus is to
experimentally characterize the effect of variation in motive gas supply pressure,
entrainment ratio, back pressure conditions, nozzle injection position operated
together with a COIL device and discern the reasons for the behavior.
Results of
experimental studies on production of nanostructured silicon carbide powders in
a plasma-chemical reactor based on a two-jet plasmatorch are presented. The
conditions of SiC formation as a function of temperature and composition of the
initial components are determined by thermodynamic calculations. Possibility of
silicon carbide synthesis with the size of particles of 5-20 nm is shown experimentally.
The flow field passing through a highly loaded low pressure (LP) turbine cascade is numerically investigated at design and off-design conditions. The Field Operation And Manipulation (OpenFOAM) platform is used as the computational Fluid Dynamics (CFD) tool. In this regard, the influences of grid resolution on the results of k-ε, k-ω, and large-eddy simulation (LES) turbulence models are investigated and compared with those of experimental measurements. A numerical pressure undershoot is appeared near the end of blade pressure surface which is sensitive to grid resolution and flow turbulence modeling. The LES model is able to resolve separation on both coarse and fine grid resolutions. In addition, the off-design flow condition is modeled by negative and positive inflow incidence angles. The numerical experiments show that a separation bubble generated on blade pressure side is predicted by LES. The total pressure drop has also been calculated at incidence angles between -20° and +8°. The minimum total pressure drop is obtained by k-ω and LES at design point.
Keywords: comprehensive optimization, GT and CCPP cycles, gas turbine flowpath, water injection into air compressor, economy and power efficiency
Pages: 483– 491
The objects of study are
the gas turbine (GT) plant and combined cycle power plant (CCPP) with
opportunity for injection between the stages of air compressor. The objective
of this paper is technical and economy optimization calculations for these
classes of plants with water interstage injection. The integrated development
environment “System of machine building program” was a tool for creating the
mathematic models for these classes of power plants. Optimization calculations
with the criterion of minimum for specific capital investment as a function of
the unit efficiency have been carried out. For a gas-turbine plant, the
economic gain from water injection exists for entire range of power efficiency.
For the combined cycle plant, the economic benefit was observed only for a certain
range of plant’s power efficiency.
