Vibration analysis of wind tunnel support

Journal of Harbin Institute of Technology (New Series), Vol. 11, No. 5, 2004Vibration analysis of wind tunnel supportZHANG Xu' , ZHANG Jia-tai' ，DONG Guo-qing，ZHANG Guo-you , LIU De-fu2张旭，张家泰，董国庆,张国友，刘德富(1. College of Mechanical and Electrical Engineering, Harbin Engineering University, Harbin 150001 ，China;。Acrodynamic Research Institute, Harbin 150001，China)cing mechanical resonance and excessive vibration displacement, five kinds of wind tunnel support structureshave been simulated and analyzed individually under five different load conditions by means of a nonlinear finiteelement numerical method./ith natural frequency and three directions vibration displacement given, simula-tion and analyses indicated that additional supports is more beneficial than heightening the rigidity of steel rein-forced concrete in support pillars and adopting steel wrappers on the pillars to increase natural frequency of sup-port structure. Increasing the rigidity of steel reinforced concrete ，adopting steel wrappers and providing addi-tional supports are all helpful in redueing three directions vibration Max displacement. and additional supportsare comparatively more ffective. Therefore, a structure scheme with steel reinforced concrete support pillars,steel wrappers and additional supports should be adopted in practical wind tunnel support construction.Key words: wind tunnel support; finite element ; natural frequency ; three directions Max displacementCLC number: TG31Document code: AArticle ID: 1005-9I 13(2004 )05-0510-03In recent years, high property requests for subson-Tab.1 Classification of wind tunnel support structure schemesic and supersonic speed advanced flight has beenClassificationStructure schemebrought up continuously in research and development ofaviation and space flight'.2l. Since wind tunnel sup-With concrete support pllars0 Yes Yes YeYesport is indispensable to airplane development, it is veryimportant to improve the stability of wind tunnel supportWith steel wappers on the pllas No No Yes Yes Noto effectively remove the interference effeet in wind tun-With additional supportsNoNo Yes No Yesnel tests and to improve test accuracy[3.4]In this pa-per, five kinds of wind tunnel support structures aresimulated individually under five load conditions bymeans of nonlinear finite element numerical methods toachieve a practical and feasible structure scheme thathas high enough natural frequency to prevent the struc-ture from mechanical resonance and excessively largevibration displacement. .Wind Tunnel Support Structure Schemes andLoad Conditions1.1 Wind Tunnel Support Structure SchemesAs shown in Tab. 1, there are five kinds of windtunnel support schemes mainly based on whether theyare steel reinforced concrete support pillars, with steelwrappers on the pillars and with additional supports onFig.1 Structure scheme I1 of wind tunnel support andnol. A structure scheme II with concrete support pil-load positionslars，with steel wrappers and additional supports is1.2 Load Conditionsshown in Fig. 1. The upper strueture is a steel frame and中国煤化工tures, gravity and windthe left lower structures are steel reinforced concreleSine torque and inertiasupport pillars with steel wrappers. The part positions of:MHC N M H Ge harmonic load. The twoother structure schemes are all completely consistent.kinds ot load are analyzed ndependently to help studyReceived 2002 -09 - 28Sponsored by project KF2001045 from Chinese Aerodynamic Research Institute.方万数据Journal of Harbin Instiule of Technology (New Series), Vol. 11, No.5, 2004their respective effect on the structures. Inner sides ofcated as the armplitude of the harmonic vibration dis-two upper and lower circle plates on the left steel frameplacement.exert gravity -3 000 N in X direction and wind forceDifferent orders of the natural frequency of all750 N in Y direction respectively, load positions ofstructure schemes is given in Tab. 2, which is a fur-wind force are at the center of the plates shown in Fig.ther base analysis of harmonic vibration. First, order1. The two circle plates are exerted sine torque 5 500natural frequency of wind tunnel support without addi-sinwt (N●m) at only one position couple, corre-tional supports is from5 Hz to 6 Hz，while frst ordersponding with five different conditions, five part posi-natural frequency of wind tunnel support with addition-tion couples on - 90°，-45°, 0°，45° and 90° areal supports is about 11 Hz. To all appearances, onlycorrespondingly expressed as point C andd, point e andheightening the rigidity of support pillars and adoptingf, point g and h, point i andj, point h and l. Additional-steel wrappers have less effect, but adopting aditionally, sine inertia force 3000sin wl (N) is exerted nearsupports has greater efect on natural frequency of thefront and behind ends of straight rods with point a and bstructures. Adopting additional supports helps to makeand near point 5 and 6 on the right part of the struc-natural frequency of the structures far from the load fre-ture. The following position and value of various loadsquency，thereby three directions vibration displacementare the same as the above mentioried correspondingly,can be lessened. When load frequency changes fromnot referred to later in this paper.2.5 ~5 Hz, vibration displacement increases with nat-ural frequency. Sixth order natural frequency of all2 Simulation Results and Analysisstructure schemes does not reach to 18 Hz.By means of finite element software ANSYS, thTab.2 Different orders of the natural frequency of allfive structure schemes of wind tunnel support understructure schemesfive different load conditions mentioned above haveClassfcationNatural frequeney/Hzbeen simulated from a static and vibration mode view.Twenty-five corresponding results are analyzed altogeth-First order natural frequency5.834 4.995 11.054 5.024 10.960er and individually.According to Von Mises stress distribution resultsSecond order natural frequency5.966 5.742 12998 5.766 12 997of static simulation, the deformation of all structures isThird order natural frequency7.681 6.910 13.835 6.942 13.822transparently among the elastic range. The stress anForth order natural frequency11.209 10.955 14. 289 11.048 14. 144strain of welding positions on a structure”s steel frameFifth order natural freqpuency14.844 13. 582 16.401 13. 763 16. 315are far larger than those on any other positions. X，Yand z three directions Max displacement caused by grav-Sisth order natural frequency15.035 I4.557 17.454 14. 62017. 450ity together with wind force are not to exceed0.0245 mm, 0.015 mm and 0. 019 mm respectively,Three directions Max displacement of structurewhich are all within the permissive displacement range.scheme I is given in Tab. 3. The model of the struc-All structure schemes are safe from statics view.ture doesn' t consider support pillars deformation， soVibration model analysis is as follows. Hereafter,displacement is not large. Inertia force has somethree directions displacement is indicated as harmoniceffect, but only on the right weak frarme, not on the leftvibration displacement, and Max displacement is indi-principal structure parts.Tab.3 Three directions Max displacement of structure scheme ILoad conditionMax displacemen/ mmTorque on -90Torque on -45Torque on 0°Inertia force onpositionright six pointsX direction Max displacement0. 1330. 1370. 1240.474Y drection Max displacement0. 4050. 2680.063.0. 598Z direction Max displacement0. 1460. 1620. 3070.323frame.scheme II is given in Tab. 4. Because the elasticityThree directions Max disnlacement of structuremodule of support pillars material is less than that ofscher中国煤化工cause of the three di-steel structures material, the deformation of supportrectic-upports, three direc-pillars is larger. Then displacement on the left princi-pal structure parts is larger along with the lower supportplacement on the left principal structure parts is lesserpillars. Inertia force has more ffet on the right weakthan that on the right weak frame.●511●Journal of Harbin lnstitute of Technology (New Series), Vol. 11, No. 5, 2004 .Three directions Max displacement of all structurestructure scheme 1 and V, it is indicated that addition-schemes exerted torque on 0° position is given in Tab.al supports are more helpful to Max displacement than6. By analyzing structure scheme I and II, it is indica-heightening the rigidity of support pllars. By analyzingted that heightening the rigidity of the steel reinforcedstructure scheme II, IV, l1 and V, it is indicated thatconcrete support pillars is helpful to lessen three direc-additional supports are more helpful to lessen Max dis-tions Max displacement. By analyzing structure schemeplacement than steel wrappers.1 and IV, it is indicated that additinal supports areTo sum up，in practical wind tunnel support con-very helpful to lessen three dreetions Max displace-struction, structure scheme I[ with all of the steel re-ment. By analyzing structure scheme II and V, it isinforced concrete support pillars, steel wrappers andindicated that steel wrappers have a much lesser effectadditional supports should be adopted.on three directions Max displacement. By analyzingTab.4 Three directions Max displacement of structure scheme lLoad conditionMax displacemen/ mmTorque on -90° Torque on -45°Torque on 0°Ineria force onpositionright six pointsX direction Max displacement1.0322.2332. 142.5. 432Y direction Max displacemnent6. 7448. 3996. 05620. 921Z direction Max displacement5. 37820. 16313. 258.45. 957Tab.5_ Three directions Max displacement of structure scheme 1Force conditionMax displacement/ mmTorqueon -90 Torqueon -45° Torque on0° Torque on 45° Torque on 90° Inertia force on0. 1060. 1240. 1170.1310. 1280.106Y dreetion Max displacement0.0210. 02:0. 0150.0280. 0250. 0272 direction Max displacement0. 0220.0300. 0210.0350. 033Tab.6 Three diretions Max displacement of all structure schemes exerted torque on 0 positionCissification111vX directin Max displacement0.1292. 058.1. 4040. 113Y direction Max displacement0. 0656.0843.0310.0170. 33313. 0434.096tal investigation on tapered cylinders for highway support3 Conclusionsstructures [J]. Jourmal of Wind Engineering and Indus-trial Aerodynamics, 2001 ,89(14-15): 1311 - 1323.1) AlI wind tunnel support structuretures simulated[2]GLAZKOV S A, GORBUSHIN A R, IVANOV A I, etal. Recent experience in improving the accuracy of walland analyzed are safe from a statics view.2) Additional supports have greater efeet oninterference corrections in TsAGI T-128 wind tunnel[J]. Progress in Aerospace Sciences, 2001 ,37(3): 263heightening natural frequency.- 298. .3) Heightening the rigidity of support pllars, a[3] SMTTHAL, MEE DJ, DANIEL WJ r, et al. Design,dopting steel wrappers and adopting additional supportsmodelling and analysis of a six component force balanceare all helpful to lessen three directions Max displace-for hypervelocity wind tunnel testing[J]. Computers andment, among which the third has more effect.Structures, 2001 ,79(11): 1077 - 1088.4) Structure scheme with steel reinforced concrete[4]YANG Lizhi, LI Junfu, DONG Jun. Computational in-vestigation of longitudinal support interference in highsupport pillars, steel wrappers and additional supportsspeed wind tunnel [J]. Experiments and Measurementsshould be adopted in practical wind tunnel support con-struction.中国煤化工5(3):84 -89.References:MHCNMHG[1] BOSCH H R, GUTERRES R M. Wind tunnel experimen-