As boundary condition is used the initial radius r r at α e=0° (condition of the exit velocity) and the flow area at exit A e. The contour of the nozzle on interval t-e is calculated by the method of characteristics through construction expansion waves inside the nozzle. The nozzles designed by the characteristic method ( Figure 993) have the most uniform velocity field at the exit. There are analytical methods of design of contour diverging nozzle, where the contour of the nozzle is approximated by a polynomial (first-order, second-order and the like). Ideal contour of the diverging section of de Laval nozzle is designed by the method of characteristics. Figure 475 shows the usual converging nozzle contour that can also be applied to non-circular channels and blade channels.ĥ17 i-s diagram used in the description ideal expansion of gas through a CD nozzle This condition must also satisfy the streamlines at the wall of the nozzle. It means the outlet velocity should be in axial direction of the nozzle. Ideal contour of converging nozzleĪn ideal contour of the nozzle is smooth, parallel with streamlines (on the inlet even the exit to avoid not a rise of turbulence through sudden change of direction of flow velocity at the wall), on the exit must be uniform velocity field (this condition is confirmed by experiments ).The solution of this problem is shown in the Appendix 102. You do not solve a situation behind the nozzle. (b) calculate the outlet velocity and (c) the mass flow rate of air. (a) find if the flow through the nozzle is critical flow. The narrowest area of the nozzle has 15 cm 2. Surroundings pressure behind the nozzle is 0,25 MPa. s -1, its pressure is 1 MPa, its temperature is 350 ☌ at the inlet of the nozzle.Problem 102The air flows through a nozzle, its velocity is 250 m
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