Applied software  NSF-3


Nonsteady Flow 3D

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The programm NSF-3 is designed for mathematical modeling of non-stationary 3D flow of viscous heat-conductioned gas in a complex form channels, including modeling of flow in elements of an air-gas path of internal combustion engine.

The designing of an air-gas path of an engine and the optimization of swirl in cylinders of a diesels are the important scientific problem. Numerical researches allow to reduce volume of labour-consuming and expensive experimental researches and to increase accuracy of received results. The programm NSF-3 was developed in Internal Combustion Engine Department of Bauman Moscow State Technical University for decision of these problems. In a basis of a complex there are the decision of the system of non-linear differential equations in private derivatives that describe non-stationary flow of compressed viscous heat conducting gas in volume with mobile boundaries.

The numerical calculation is made with the help of author's modification of "particles in cells" method by Harlou and of "large particles" method by Davidov, that allows to considerably reduce the required resources of computer and to increase stability of the decision at small flow speeds and at small gradients of gas parameters.

NSF-3 complex makes it possible to receive the fields of speeds, of pressure, of Mach numbers, of temperatures, of density and of other parameters for both stationary, and non-stationary flows. There is also realized the visualization of flow pictures, allows observing the separated and stagnant zones, the connection zones of coming off jets, the jumps and complex spectral configurations, that formed at supercritical differences of pressure, the vortex pathes, the various sorts of instabilities and other gas-dynamic effects.

There are special programs in the structure of this complex.
For example there is code to compare the various variants of designs among themselves. Program compares the losses of immobilized flow pressure, flow rates, fluctuations of parameters.

The complex NSF-3 is used by the developers on processors Pentium.

With the help of numerical solutions there were developed the ways of significant losses decrease in engines collectors by Yaroslavl motor plant, Kolomna diesel locomotive plant and ZIL motor plant. In particular, as a result of decreasing of losses in the intake manifolds of diesel ZiL-645, its specific fuel consumption was reduced on 2-4 g/(KW*h) in the all range of working regimes.

Results of numerical research of inlet valve channels of the four stroke diesel by joint-stock company "Volgodieselmash"

In a base design of channel there are some sites with saltatory changes of the cross section area and with sharp turns of walls.

In the result of 3D flow calculation was found that some factors of a channel design are the parents of formation the separation zones, of high losses and of the first valve channel underloading (first toward the flow)

After the elimination of defects of the valve channel the calculation of 3D gas flow was carried out again. Results of calculation have shown that the charge of air through valve channels was levelled, and general factor of the charge was increased on 21 %. It will allow, according to calculations by the DIESEL - 2/4t code, to increase the diesel capacity on 13 KW, and to lower the specific fuel consumption on 3 g/(KW h).

The boundary conditions simulated a static scavenging of valve channels with pressure and temperature which are characteristic for intake process on a regime of complete capacity in view of supercharging.

The example of calculation of swirl in the cylinder and combustion chamber of diesel GAS 5441 by use of NSF-3 code

The Automatic generator of a mobile grid with fractional cells on borders allows:
- to take into account a movement of the piston and valves;
- to describe an any complex settlement area without excessive increase the quantity of cells.

The developer of code: The Automatic generator of a mobile grid is
Ph.D. Andrey Kuleshov
E-mail:
kuleshov@power.bmstu.ru

The maximum quantity of cells in this example is 500 000
The calculation begins at the moment of opening the valve and comes to end in top of the compression stroke.

The fields of speeds and of pressures in sections of settlement area.

The displayd fields of speeds and of pressures are corresponded to the angle of crankshaft turn - 40 degree after the TDC.

A falling part section of the inlet channel (is lower than a screw part)

The initial conditions and boundary conditions (dependence on time of pressure and the temperatures on an entrance in the channel) are determined on the results of calculation with the using of the programm DIESEL-2/4 t.

The cylinder section on a plate of the valve.

Means of a picture visualization of flow allow to look through not only field of pressure and of speeds, but also of temperatures, of density, of Mah`s numbers and other.

Section on a stalk of the valve and on chamber in the piston.

 

The chief of the project:
Ph. D. (Eng.) Yuri A. Grishin.
Tel. (095) 573-70-79; E-mail: grishin@power.bmstu.ru;
Grishin Yu.A., Piston Engines Department (E-2), MSTU, 2-Baumanskaia, 5, Moscow, 105007, Russia.

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