# The Jet System Theory

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The jet system theory The jet system is formed due to the interaction of free turbulent jets, issuing from nozzles (openings) that are arranged in a different geometrical way in the outlet plane. Stankov (1998) has investigated experimentally wide range of jet systems, issued from nozzles with square, circle and rectangular shape. He has found that the nozzles can be arranged, following schemes, which makes easier the prediction of the flow, issuing from a jet system with endless number of openings. In the case of “in-corridor” ordered nozzles, the jet system with endless number of opening is described by 9 jets (3x3), as shown in Fig. 1. Every 8 jets, that surround а central jet, are representative for the whole system and play the role of…show more content…
The typical characteristics of the jet system geometry can be described by using the geometry of the threads and the pores in the woven textile layer. The approach has already been applied and verified in the work of Angelova, Stankov, Simova & Kyosov (2013). The representative steps between the jets in the system Sy and Sz (Stankov, 1998) are described by the following expressions (Fig. 1): where dwp and dwf are the mean diameter of the warp and weft threads respectively, mm; b is the mean size of the pore, mm, assuming that its width 2bz and its height 2by are equal, i.e the pore has as square shape and b=2bz=2by. In the case of square pores (square shape of the nozzle openings), the size of the pore b is: , where Sm is the mean pore area, mm, determined theoretically or…show more content…
The continuity eq. (4) was added to the partial differential equations (1)-(3): (4) To model the heat transfer the energy equation (5) was added to the RANS system: (5) where is the density of the fluid, kg/m3; E is the energy; is the velocity vector; p is the pressure, Pa; T is the temperature, K; keff is the effective conductivity, defined as for k – thermal conductivity of the material and kt – turbulent thermal conductivity; is the sensible enthalpy; is the diffusion flux of species j; is the effective viscous stress tensor; Sh is a term for the heat transfer of chemical reactions and any other heat sources defined. To close the system of partial differential equations tow turbulent models were tested: and RSM (Reynolds Stress