tailieunhanh - Aerospace Technologies Advancements 2012 Part 11

Tham khảo tài liệu 'aerospace technologies advancements 2012 part 11', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Integrated Vehicle Health Management for Solid Rocket Motors 285 Fig. 16. left Nozzle pressure black line in the nominal regime is compared with the calculations of the fault induced pressure using 1D model blue dotted line and scaling algorithm red dashed line . right Nozzle vacuum thrust black line in the nominal regime as compared to the deviation of the thrust from nominal regime calculated using scaling algorithm cyan dashed line and 1D calculations blue dotted line . The time-traces of the hole thrust calculated using scaling equations and 1D algorithm are shown by magenta dashed line and red dotted line respectively. To calculate nozzle thrust the empirical constant thrust coefficient was used CF - FN I pAt N CF N - CF D. 50 If combined with 44 the following result for the deviant nozzle thrust FDi can be obtained 1 FDi - FNi - At Di K At Ni A JI At Di 1-n-q 51 Eq. 51 can be used to calculate the side breach thrust. The resulting expression for the side vacuum thrust pamb 0 can be simplified Y Fh - p0 Ah -I I y 1 . I Y 1J 52 The algorithm suggested in earlier work McMillin 2006 consists of iteration of Eqs. 46 49 until convergence of Ati is achieved. On substituting Eq. 48 into Eq. 49 and Eq. 49 into Eq. 47 the equations. 46 - 49 can be reduced to two equations in the form AtDi - AtNi n 1-n-q AtD i f tD i - tf J Ati tD i - tD i-1 AtDi. 53 where tDi is given by 46 . There are three unknown variables AtDi Am tDi in two Eqs. 53 therefore one more equation is needed to implement iterative procedure. We use assumption McMillin 2006 that the nozzle throat area is only a function of time AtD tDi AtN tDi which holds for actual rocket parameters. 286 Aerospace Technologies Advancements We now verify both algorithms by direct comparison of their performance in off-nominal regime with the fault initial time 10 sec and initial hole radius 0 in. The results of the calculation of pressure nozzle and side thrusts using model integration and scaling equations are shown in .

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