Influence of the opening angle of a conical supersonic nozzle on the structure of initial interval of non-isobaric jet |
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Authors: | V N Vetlutsky V L Ganimedov M I Muchnaya |
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Institution: | (1) Khristianovich Institute of Theoretical and Applied Mechanics SB RAS, Novosibirsk, Russia |
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Abstract: | The ideal gas exhaustion from an infinite volume into a gas at rest through a supersonic conical Laval nozzle is considered.
The problem was solved numerically by steadying in time in a unified formulation for the regions inside the nozzle and in
the ambient environment. In such a statement, the nozzle outlet section is no internal boundary of the region under consideration,
and there is no need of specifying the boundary conditions here. Local subsonic zones arising in the flow lie inside the region
under consideration, which eliminates the possibility of using a marching technique along one of the coordinates. The numerical
solution is constructed by a unified algorithm for the entire flow region, which gives a possibility of obtaining a higher
accuracy. The computations are carried out in the jet initial interval, where, according to monograph 1], the wave phenomena
predominate over the viscous effects.
The exhaustion process is described by the system of gas dynamics equations. Their solution is constructed with the aid of
a finite difference Harten’s TVD (Total Variation Diminishing) scheme 2], which has the second approximation order in space.
The second approximation order in time is achieved with the aid of a five-stage Runge-Kutta method. The solution algorithm
has been parallelized in space and implemented on the multi-processor computer systems of the ITAM SB RAS and the MVS-128
of the Siberian Supercomputer Center of SB RAS.
The influence of the semi-apex angle of the nozzle supersonic part and the pressure jump between the nozzle outlet section
and the ambient environment on the flow in the initial interval of a non-isobaric jet is investigated in the work. A comparison
with experimental data is presented. The computations are carried out for the semi-apex angles of the nozzle supersonic part
from 0 (parallel flow) to 20 degrees. For all considered nozzles, the Mach number in the nozzle outlet section, which was
computed from the one-dimensional theory, equaled three. Computations showed that in the case of flow acceleration in a conical
supersonic nozzle, its geometry is one of the main factors determining the formation of the jet initial interval in ambient
environment. |
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