Rao claims nozzle contour would not strongly depend on $\gamma$, but any formula I have found dealing with angle in supersonic flow (Prandtl-Meyer function and ideal exit angle most prominently) heavily depend on $\gamma$. Generally speaking, I don't trust the graph anymore. (Most calculations I found are for $\gamma=1.2$ or $\gamma=1.23$) However, plotting it for different mach numbers against their corresponding area-ratios would result in similar graphs only for $\gamma = 2.15$ (at 100%, exit-angle only), an unusually high specific-heat-ratio. Upon careful reading, Rao himself mentions a formula for the exit-angle of a thrust optimised parabolic nozzle. of first meeting JANAF Liquid Propellant Group, Johns Hopkins University, Md., Nov.1959. Rao G.V.R, "Optimum Thrust Performance of Contoured Nozzle", Bull. 29 of pdf Followed the references as far as I could, but even my university library couldn't find this: A computational mesh, with a prysmatic boundary layer is constructed using Gmsh and Engrid mesh generators and the ow computations were performed using OpenFoam nite volume density solver rho-CentralFoam. A nozzle contour designed to produce parallel, uniform exit flow, thereby yielding 100 percent geometric nozzle efficiency, is called an ideal nozzle. There are several classes of bell-type nozzles from which to choose. Just for completeness, some other sources where I found this specific graphic reproduced: p. an optimized thrust rocket nozzle with high pressure rate. The optimum nozzle contour is a design compromise that results in a maximum overall nozzle efficiency. The first nozzle’s results are considered in this. characterized by downstream Mach numbers close to 1.5 and 2. So I played around with many ideas, none of them leading to the graph mentioned. Typical open-source mesh generators compatible with the CFD solver are salome-platform from OPEN-CASCADE and Gmsh. Results pictured higher exit rate and better degree of flow separation with contour nozzles compared to it off with corresponding cone like nozzle. what is that paper called? It is not part of Rao's original paper, where I would have expected it.) No occurrence of shocks is determined with higher divergent angles. Are they purely empirical? If so, is the data available somewhere? (i.e. However, I couldn't find any concrete mathematical formula to calculate these angles. I've found many references to a graph that is shown in Sutton
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |