1、MEETING ON GROUND WIND LOAD PROBLEMSIN RELATION TO LAUNCH VEHICLESProvided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-iPREFACEAn unclassified technical meeting on ground wind loadproblems in relation to launch vehicles was held at the LangleyResearch Cen
2、ter on June 7 and 8, 1966. The meeting coveredseveral sessions having the following topics: Specific VehicleResults; Definition of Atmospheric Inputs; Experimental andAnalytical Simulation Techniques; Basic Studies of CylindricalBodies; and Where Do We Go From Here? - The Designers Viewpoint.The pur
3、pose of the meeting was to provide a forum for directexchange of information and ideas between government, industry,and university personnel who are actively engaged in this areaof work. In addition to focusing attention on current researchand development information, the meeting also attempted to o
4、fferuseful guidance on existing programs and on planning futureefforts. The size of the meeting was kept small in order toencourage informal across-the-conference-table discussions amongthe attendees. In order to promote timely distribution of thepapers presented at the meeting, this document has be
5、en printedusing copy provided by the authors without the customary NASAediting.i i_1966022936-002Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-CONTENTSPREFACE iSESSION I - SPECIFIC VEHICLE RESULTS 1.0Chairman - A. Gerald Rainey, NASA Langley Resear
6、ch CenterHIGHLIGHTS OF GROUND-WIND TESTS AT AMES I.i/By Donald A. Buell, NASA Ames Research CenterSUMMARY OF LANGLEY WIND TUNNEL STUDIES OF GROUND-WINDLOADS ON LAUNCH VEHICLES . 2.1 fBy Moses G. Farmer and George W. Jones, Jr.NASA Langley Research CenterSATURN V GROUND WIND PROGRAM . 3.1 “jBy Robert
7、 M. HuntNASA George C. Marshall Space Flight CenterA FULL-SCALE GROUND WIND LOAD RESEARCH PROGRAM 4.1 /By Jerome T. Foughner, Jr., and Rodney L. DuncanNASA Langley Research CenterGROUND WIND INDUCED OSCILLATIONS OF THE TITAN IIIITL TRANSPORTER . 5.1 /By J. M. Lyons and A. J. Lum, Aerospace Corporati
8、onAERODYNAMIC EXCITATION OF STRUCTURES BY WIND - A REVIEW /OF RECENT WORK AT THE NPL 6.1By R. E. Whitbread, National Physical Laboratory,Eng andSESSION II - DEFINITION OF ATMOSPHERIC INPUTS 7.0Chairman - Harold B. Tolefson, NASA Langley Research CenterCONSIDERATIONS AND PHILOSOPHY OF GROUND WINDS CR
9、ITERIAFORMULATION . 7.1 121By William W. VaughanNASA George C. Marshall Space Flight CenterGROUND WIND MEASUREMENTS AND ANEMOMETER RESPONSE . 8.3./IBy James R. ScogginsNASA George C. Marshall Space Flight CenterWIND MEASUREMENTS USING A VERTICAL ARRAY OF FAST RESPONSEANEMOMETERS . 9.1/By Rodney L. D
10、uncan and Jerome T. Foughner, Jr.NASA Langley Research Center _iii PRECEDING PAGE BLANK NOT FILMEI_1966022936-003Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-THE RELATIONSHIP OF WIND STRUCTURE TO WIND LOADING 10.11By A. G. DavenportUniversity of W
11、estern Ontario, CanadaSESSION III- EXPERIMENTAL AND ANALYTICAL SIMULATIONTECHNIQUES ii.0Chairman - Wilmer H. Reed, IIINASA Langley Research CenterLABORATORY SIMULATION OF ATMOSPHERIC MOTIONS IN THELO STONE 11.1-“U iiit9.By J. E. Cermak, ColoTado State e sAN APPROACH TO THE WIND TUNNEL MODELLING OF T
12、HE RESPONSEOF STRUCTURES TO THE NATURAL WIND 12.1_By A. G. DavenportUniversity of Western Ontario, CanadaPREDICTIONS AND IMPLICATIONS OF THE FLOW FIELD PARAMETERANALYSIS OF THE WIND INDUCED OSCILLATION PROBLEM . . 13.1-By Wayne E. Simon, Martin Company/DenverTHE AMES WIND-TUNNEL GUST GENERATOR . 14.
13、1-By Donald A. Buell, NASA Ames Research CenterUSE OF AIR INJECTION IN THE SIMULATION OF ATMOSPHERICPROCESSES 15.By Richard E. Thomas, Texas A and M UniversityNUMERICAL SOLUTION OF THE EQUATIONS OF CONTINUUM MOTION:VORTEX FORMATION AND SHEDDING IN A VISCOUS COMPRESSIBLEFLUID 16._By John G. Trulio, A
14、pplied Theory, Inc.SESSION IV - BASIC STbDIES OF- CYLINDRICAL BODIES . . 17.0Chairman - y. C. FungCalifornia Institute of TechnologySOME WATER TABLE EXPERIMENTS ON OSCILLATING CYLINDERS . . 17.1By Leon Schindel and Garabed ZartarianMassachusetts Institute of TechnologyAMPLITUDE AND SURFACE PRESSURE
15、MEASUREMENTS FOR A CIRCULARCYLINDER IN VORTEX-EXCITED OSCILLATION AT SUBCRITICALREYNOLDS NUMBERS _ _ _ _ _ . - - - 18.1By G. V. Parkinson, University ;f Briti;h Columbia, Canadaand N. Ferguson, Nova Scotia Technical College, NovaScotia1966022936-004Provided by IHSNot for ResaleNo reproduction or net
16、working permitted without license from IHS-,-,-FLUCTUATING FORCE MEASUREMENTS UPON A CIRCULAR CYLINDER . . 19.1-_By Louis V. SchmidtU. S. Naval Postgraduate SchoolEXPERIMENTAL INVESTIGATION OF WIND INDUCED OSCILLATIONEFFECTS ON CYLINDERS IN TWO-DIMENSIONAL FLOW ATHIGH REYNOLDS NUMBERS . 20. lj -_By
17、Joseph J. Cincotta, Martin CoIBaltimore, George W.Jones, Jr., NASA Langley Research Center, and Robert I!W. Walker, NASA Marshall Space Flight Cen%er !gTHEORY OF _ RESPONSE OF A SLENDER VERTICAL STRUCTURE /TO A TURBULENT WIND WITH SHEAR 21 ,I JBy Bernard Etkin, University of Toronto, CanadaF_FECTS O
18、F TURBULENCE ON VORTEX SHEDDING FROM CIRCULAR |CYLINDERS . 22. I-IBy M. Sevik, ThePennsylvania State UniversityIMPULSIVE AND ACCELERATED FLOW ABOUT CYLINDERS 23.1-IBy TUrgot Sarpkaya, University of NebraskaSESSION V - WHERE DO WE GO FROM HERE? - THE DESIGNERSVIEWPOINT 24.1 -/Chairman - A. Gerald Rai
19、ney, NASA Langley ResearchCenterLIST OF ATTENDEES . 25.1 _Iv1966022936-005Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-SESSION I - SPECIFIC VEHICLE RESULTSChairman - A. Gerald Rainey, NASA Langley Research Center1.01966022936-006Provided by IHSNot
20、 for ResaleNo reproduction or networking permitted without license from IHS-,-,- i4t :_-“HIGHLIGHTS OF GHOUND-NIND TESTS AT AMES _by Donald A. BuellGround-wind loads research a_ Ames Research Center has pri-marily involved specific configurations of launch vehicles. _“Since the models were three-dim
21、ensional with various stage con-figurations and protuberances, they did not present a convenient _tool for generalizations. However, they exhibited a ,.umber ofcharacteristics which help to define the scope of the problem of i_esti_.tng 8round-wind loads. In particular, the tests pointedu_ the m_gni
22、tude of configuration effects fach as payload shape, _roughnePs of the cylindrical surface, conduits, and tmblltcal ttowers. Neasurements included dynamic and steady-state bendingmoments, steady-state forces, and fluctuating and steady-state r_pressures. The results were reported in detail in NASA T
23、N D-1893and TN D-2889. ,The intention of this present,milCh ls to discuss a few typl- 7oal results in the lisht of data that has been subsequently ac-quired by other researchers. Only the oscillatory loads perpen- _dicular to the airstream will be considered. This is probablythe least predictable pa
24、rt of the wind loads which can be stud_.ed Iin the conventional wind tunnel. Definition of symbols is thesame .as J.n the previously mentioned l_blloations.SIMULATIONReynolds number and reduced frequency, based on the firstmode cantilever frequency, have been assumed to be the most impor-tant; facto
25、rs in the vehicle simulation. Representative _ull-seale1.1 _.1966022936-007Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-f$Reynolds numbers have been obtained in the modol tests by operat-Ing at abnormally high air densities and velocities. The Rey
26、noldsnumbers obtained with representative models are shown in figure I.They range from 0.i to I0 million. The figure also indicates theReynolds mlmbers where response measurements were made at a re-duced frequency of 0.2. When the response at this frequency waslarge, this is so noted. A reduced freq
27、uency of 0.2 is of interestbecause other investigators have observed large responses a_ thisfrequency at both subcrltical and supercritlcal Reynolds numbers. _In addition, this frequency has been predicted in numerical studies Iof vortex shedding, i_Figure 1 shows that the Ames moaels had only a few
28、 case_ oflarge response at fD/V = 0.2. But the figure also shows that mostof the response meam_rements at this frequency were made at Rey-nolds numbers between 0.5 and 2 million. I_ _ppears, therefore,that this range of oupercritlcal Reynolds _bers involves a tran-sitional type of flow _hlch inhibit
29、s vortex shedding at the usualfrequency. The idea of a broad translt_al range of Reynoldsnumbers was suggested by Roshko for two-dimenslonal cylinders,although he was considering somewhat dlfferent characteristicsof the flow. ,SLENDER NOSE r )DELSAnother factor whloh had a pronounced influence on th
30、e re-suits was nose shape. For example, the arge responses referredto in figure 1 occurred only on models with a “slender“ nose, suchas are shown in the model sketches. Most of the slender nose1.2i1966022936-008Provided by IHSNot for ResaleNo reproduction or networking permitted without license from
31、 IHS-,-,-models tested at Ames were not pro_e to oscillate at any frequencyor Reynolds number_ but there were exceptions which produced quite rviolent responses. E:amplee are shown in figure 2, which presents /Ithe variation of a response coefficient with reduced velocity. AReynolds number scale is
32、also included. The response coefflci_nthas been obtained from the maxl_ul dynamic bending moment occur-ring in approximately I000 cynles. The low _alues of response co-efficient in figure 2 represent a random motion. Th_ larger re-sponses were of the narrow-band periodic type, such as car be pro-duc
33、ed by a negative aerodynamle damping. More precisely, an In-crease in model motion above some minimum amplitude increased theexcitation until a nonlinearity llmLted the amplitude.There are many factors which can alter the results with thistype of phenomenon. In the case of the model on the left side
34、 offigure 2, roughness decreased the random response, en effect whichwas observed generally on slender nose models. This reduction wasapparently sufficient to ellm_nate the motlon-coup_ed excitation.Other models with similar shapes but with higher structural da_p-Ir_ and _tlffness showed little evid
35、ence of the narrow band responseat any R_ynolds number. Pressure measurements on a relativelystiff model failed to reveal a narrow band excitation over a widerange of frequency and Reynolds number.In contrast, the model on the rlgh_ o_elllated under a varietyof test conditions, smooth or rough, desp
36、ite having a higher struc-tural damping. This may have been caused by the fact that it had ,somewhat less stiffness, in proportion to volume, than the firstmodel and had only half the relative density ratio. It was thusJ1.3-_-1966022936-009Provided by IHSNot for ResaleNo reproduction or networking p
37、ermitted without license from IHS-,-,-more readily accelerated to large motions by a random exottatlon,The addition of a horizontal plate under the nose greatly reducedthe response for this model, which may Ir_icate that the flowaround the nose is important to the motlon-eoupled excitation,However,
38、the response peaks for this model occurred at such lowReynolds numbers that one must be cautious of generalizations.It is presumed that the model would have had a large response ata V/fD of 5 if the Reynolds number had been higher. This conclu-sion is strengthened by the fact that roughness moved on
39、e of thepeaks closer to that speed.BLUNT NOSE NODELSThe sttuatlonwas less complioatedwhen the model had a bluntnose, provided that the nose diameter was a significant proportionof the maxlmumdiameter. In such configurations the nose controlledthe pressure fluctuations over a length several diameters
40、 belowthe nose, and there was no motion cougiing. Typical responses formodels with hemisphere noses are shown in figure 3. The data arefor the same configuration, but the curves on the right representa larger vehicle than those on the left. Without roughness, theresponse oo_fflcient tended to increa
41、se with speed, and the slopebecame steeper as vehicle size increased. With roughness, a nar-row-band random response peak was observed, which occurred at; lowerreduced speeds as vehicle size increased. When the stmt_latecl ve-hicle reached sufficiently large proportions, the response peakbecame fixe
42、d at a V/fD of 10, and the smooth-model response curvemerged with that for the rough model.T1.4i1966022936-010Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-In ord,_rto show something ofthe flow mechanism involved,pictures were taken of the models w
43、ith oll on the surface. Fig-ures _ and 5 are photographs with and without a spoiler at thetip of the nose. The spoiler is of interest because it was veryeffective in reducing the pressure fluctuations caused by the bluntnose. It can be seen that the separation llne in flgure 4 fermi- 1nated some dis
44、tance from the tip, and that air was flowing smoothlyover the nose and into the wake. Figure 5 shows that the spoilercaused the separation line to continue over the nose, thus isolat-ing the wake from the free stream. Presumably, this broke up the 1illne of communication between the approaching air
45、and the sheddingvortices so that the coherence of the pressure fluctuations wasdestroyed. Slender noses are believed to produce an effect slml- ilar to the spoiler. ICONDUIT EFFECTSThe last factor to be considered is perturbations from thecircular cross section. Figure 6 shows data for one of the sm
46、aller !models with circular rods, representing conduits, extending _he !length of the upper stage. An upstream conduit produced verylarge responses that were motion coupled. The flow mechanism in Iwhich the conduit acts as a trigger, sending vortlcity aro_d eachside alternately, appears reasonably s
47、traightforward. Unfortun-ately, the Reynolds number is again too near the transition rangeto be sure that the same effect would be observed at higher Rey-nolds numbers. It can be seen that a second conduit near thenormal separation point nearly eliminated the effect of the upstream1.5 ilF1966022936-
48、011Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-conduit. As a consequence, multiple conduits were generallyfavorable (on this model) in holding vortex shedding loads to aminimum.CONCLUDING REMARKSIn summary, the data acquired at Ames are not in conflictwith the expectation of a response at a reduced frequency of 0.2,if the Reynolds number is sufficiently removed from transition.However, factors such as roughness, damping, stiffness, and rela-tive density ratio may profoundly affect the amplitude of
