Fuselage self-propulsion by static-pressure thrust - CAFE Foundation

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d/V0'33 = 0.0969 CHPs = 0.0404 CUP = 0.0537 The propulsive system efficiency index is S -The propulsive system efficiency index is: 7PS = CDR/CBps = 0.031/0.0537 = 57.7%. VPS = CDR/CHPs = 0.028/0.0404 = 69.3%. F. Tripped-transition Body with EmpennaRe (Equal Jet Diameter1 Equal Jet Diameter The second body/jet-thruster system is based on the For this case, the reference body drag coefficient is CDR = 0.031 and the jet diameter ratios of Conf. 12 assumption that the jet diameter is equal to that of is d/V0'33 = 0.163. the Corresponding integrated system, while the mass flow is allowed to vary. The inlet velocity will be uj/"o (uj/Uo - 1) = 0.743, taken to be Uo and the static-pressure coefficient C 'j will be taken to be Zero in all the cases below. c = (Ej - p,/g) Pt = 2.241 2 m = %/4 d pU. 3 Cm = 0.0312 C m = 0.785 (d/V0'33)2 U./U 1 0 U./U I O = (U./U I O 0.33) 2) - 1) = (0.50 CDR/0.785 (d/V D. Free-transition Body (Equal Jet Diameter1 For this case, the reference body drag coefficient is CDR = 0.024 and the jet diameter ratio of Conf. 01 is d/V0833 = 0.147. U./U (U./U - 1) = 0.707, U./U = 1.479 1 0 J O J O C = (E. - p /q ) = 2.18 Pt I 0 0 Cm = 0.0250 CBPs = 0.0337 The propulsive system efficiency index is CBps = 0.0443 Uj/Uo = 1.497 The propulsive system efficiency index is "p" = CDR/CBps = 0.031/0.0443 = 69.9% Evaluation The complete results are presented below in Table V, 'Propulsion Evaluation Summary". In terms of propulsive system efficiency, the integrated Conf. 02 (free-transition, with empennage) is best with 198.5%, while the corresponding body/wake-propeller systems E and B have 103% and 88% and the bodyljet-propulsor systems B and E have 69.3% and 55.QX. In terms of propulsive mass flow, the integrated Conf. 01 and the corresponding body/jet-propulsor system A have the lowest C = 0.0115, m while the body/wake-propeller system 1 has the highest Cm = 0.0889; the mass flow = CDR/CBps = 0.024/0.0337 = 71%. ratio is 7.55. 7PS In terms of jet total-head coefficient, the E. Free-transition Body with Empennage (Equal Jet integrated Conf. 01 has the lowest C = 0.965, while Pt Diameter the body/jet-propulsor system B has the highest total- For this case, the reference body drag coefficient head coefficient value of 4.53; the bodyrwakeis CDR = 0.028 and the jet diameter ratio of Conf. 02 propeller system 1 has a value of 1.10, which is 14% is d/V0'33 = 0.147. higher than that of Conf. 01. In terms of jet velocity ratio, Conf. 01 has the Ui/uo (Uj/Uo - 1) = 0.825, Ui/Uo = 1.536 lowest value of 0.669, while the body/jet-propulsor system B has the highest value of 2.128. = (Ej - po/g) = 2.358 In terms of jet static-pressure, all the integrated CPt 'd Cm = 0.0260 -17- configurations have jet static-pressure coefficients well over 0.50, while the body/wake-propeller systems
Configuration Integrated Conf. 00 Integrated Conf. 01 Integrated Conf . 02 Integrated Conf. 12 Body/Wake-Propeller 1 Bady/Wake-Propeller 2 Body/Jet-Propulsion A Body/Jet-Propulsion B Body/Jet-Propulsion C Body/Jet-Propulsion D Body/Jet-Propulsion E Body/Jet-Propulsion F Table V - Propulsion Evaluation Summary =2rlO) 6 0.33 d/Y Lm- 0.147 0.0118 0.147 0.0115 0.147 0 0124 0.163 0.0150 0.351 0.0869 0.240 0.0415 0.0846 0.0115 0.0861 0.0124 0.0969 0.0150 0.147 0.0250 0.147 0.0260 0.163 0.0312 among aeronautical engineers, that the best that can be done with axial pressure forces is to achieve near zero pressure drag with unseparated concave aftbodies. In this study, the integration of the radial pressure 17,20 distribution of the self-propelled Conf. 10 (transition tripped at 10% length) yielded a thrust of 0.0166; the agreement with the above 0.0168 is indeed remarkable, as it demonstrates the nature of this thrust force. - C pt VjD0 0.970 0.674 0.965 0.669 1.05 0.715 1.044 0.690 1.10 0.961 1.18 0.987 4.17 2.043 4.53 2.129 4.13 2.033 2.18 1.479 2.36 1.536 2.24 1.497 -Pj G - CHPS_ 0.52 0.0139 0.52 0.0128 0.54 0.0141 0.57 0.0182 0.175 0.0271 0.191 0.0318 -0.10 0.0417 -0.10 0.0500 "0.10 0.0537 "0.10 0.0337 -0.10 0.0404 "0.10 0.0443 Ips- 172.6% 187.5% 198.5% 170.3% 103.0% 88.0% 57.5% 55.9% 57.7% 71.0% 69.3% 69.9% are below 0.2 and the body/jet-propulsor systems are In 1983 Goldschmied" presented the experimental practically at the free-stream level, with values wind-tunnel evidence that the self-propelled freebelow 0.1. transition models (Confs. 00 and 01) were in It is quite evident that the integrated system equilibrium flight with jet total-head equal to free presents propulsion characteristics which are far stream's and jet velocities less than 70% free superior to, and radically different from, those of stream's. In this study integration of the radial conventional systems. pressure distributions seem to yield thrust much greater than the computed skin-friction O.?lO; there VI. Summarl: can be no doubt that body self-propulsion has been achieved by static-pressure thrust, with all the power Thirty years ago the experimental wind-tunnel data applied to BLC and none to reaction thrust. This is of Cerreta' demonstrated conclusively a 40% reduction indeed a significant milestone in applied aerodynamics in "equivalent drag" (including BLC power) as against for General Aviation aircraft. a streamlined body of equal volume, with transition A propulsive efficiency evaluation was also carried tripped at 10% length on both bodies; this voided the out, on the basis of the conventional badylwakestill popular "flat-plate syndrome" that substantial propeller and body/jet-thruster configurations; the body drag reductions can only be achieved through efficiency index ranged from 88% to 103% and from 55% laminar skin-friction. to 70%, respectively. On the other hand, for the The same Cerreta data also showed experimental self-propelled Goldschmied system the efficiency index wake-drags as low as 0.0022, while the computed ranged from 172% to 198%; also it is well worth noting turbulent skin-friction drag was 0.0190; clearly a that the mass flow required was only 15% of that for body thrust force of 0.0168 had to occur to make this the best wake-propeller and 50% of that for the jethappen. This voided another belief, still current thruster with equal jet diameter. -18- YII. Conclusions In conclusion, since the fuselage represents at least 50% of the total aircraft drag, fuselage self- propulsion by static-pressure thrust should yield at 'W least 25% total power reduction. A preliminary design study by F. R. Goldschmied (1984)" for 200 MPE cruise speed indicates a u
Page 1 and 2: AI AA-87-2935 Fuselage Self-Propuls
Page 3 and 4: I. Introduction This paper attempts
Page 5 and 6: ~ To simplify the problem it is ass
Page 7 and 8: the slot's leading edge: the minimu
Page 9 and 10: Fig. 9 - Photo of Wind-Tunnel Insta
Page 11 and 12: 0,010 (transition at 65% length, se
Page 13 and 14: " a. L Y w 0 2 1 .0 0.8 0.6 0.4 " 0
Page 15 and 16: Y r rn 1 .o 0.0 0.4 UliPROPiLLiD Al
Page 17: 0.987; the static-pressure Coeffici
Page 21: 23, E. J. Neumann, "Optimum Forebod

Fuselage self-propulsion by static-pressure thrust - CAFE Foundation

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