Determination of the Aerodynamic Characteristics of Flying Vehicles Using Method Large Eddy Simulation with Software ANSYS

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1 Automation, Control and Intelligent Systems 15; 3(6): Published online Deember, 15 ( doi: /.ais ISSN: (Print); ISSN: (Online) Determination of the Aerodynami Charateristis of Flying Vehiles Using Method Large Eddy Simulation with Software ANSYS Nguyen Quang Vinh Department of Radio-Eletroni, Institute of Siene and Tehnology, Cau Giay Distrit, Hanoi, Vietnam address: To ite this artile: Nguyen Quang Vinh. Determination of the Aerodynami Charateristis of Flying Vehiles Using Method Large Eddy Simulation with Software ANSYS. Automation, Control and Intelligent Systems. Vol. 3, No. 6, 15, pp doi: /.ais Abstrat: Nowadays, together with the huge development in information tehnology, the use of numerial method is no longer an obstale. It provides a lot of advantages suh as providing high preise solutions, reduing time and ost for designing and manufaturing flying vehile models and dealing with extremely omplex problems by using physial models ompared to the usual analytial methods. The operation of airplanes represents a ritial aerodynami pratial problem due to the. Interferene this artile presents a method to identify the aerodynamis oeffiients of flying vehiles for isolate using software ANSYS. CFX and ompares obtained results to the with those reeived by analytial method. Keywords: Aerodynami Charateristis, Wing, Airfoil Setion, Angle of Atta 1. Introdution One of the most pratial problems in flight struture design and operation, is the ground interferene. The aerodynamis harateristis of s are hanged in ollision phenomena. In the present paper, the isolate is investigated analyzability and numerially. The investigation taes into aount the solution of flow around a isolate whih has profile represented in Fig.1; and a simulation is arried out at angle of atta (AOA). Experimental results are presented for a Mah number ranged from.6 to. at averaged Reynolds number of.89. Fig. 1. The model profile of isolate for simulating.

2 119 Nguyen Quang Vinh: Determination of the Aerodynami Charateristis of Flying Vehiles Using Method Large Eddy Simulation with Software ANSYS Where b = 1 m; =.64 mm; l = 1.5m; b =.6 m, the flow around an isolate is modeled as inompressible at a Re number. Numerial simulations are performed with the ommerial software paage ANSYS. CFX and GAMBIT. Simulated results using numerial simulations ompared with those using analytial method whih is given in [3].. Experimental Proedure.1. Numerial Simulation Method In all efforts aerodynami studies, no matter whether they are theoretial, experimental or omputational are normally aimed at a ommon obetive: to determine the aerodynami fores and moments ating on a body moving through air. The main purpose of employing Computer Fluid Dynamis (CFD) is to predit the aerodynami fores: lift and drag, and the pithing moments, ating on the, in a way that allows to redue time and ost when omparing with the real experiment tests. An algorithm for modeling isolate with the profile shown in Fig. 1 is desribed on shemata Fig. below. Within the sope of this problem, we will isolate with the follo assumptions: The surfae is smooth hannel (bypass roughness, surfae profile); Wings endothermi (heat exhanger bypass between panels and the environment); The flow of air to flow under small angle of atta with different veloities orresponding Mah number M =.5,.6,.7,.8,.9, 1., 1.1, 1., 1.3, 1.4, 1.5,.,.5, 3. The nature of the airflow to be taen aording to GOST : temperature T 98.15K ; Pressure p v = = 1133Pa ; dynami visosity m s ρ = 1.5g m. = 5 ; density 3 Pre-Proessing Create geometry Generate mesh Solver Options of solver setting involed: initialization, solver ontrol, output ontrol, solver manager. Solving numerially the set of governing mathematial equations onservation of: mass energy momentum Selet appropriate physial models Presribe operating onditions Presribe boundary onditions at boundary zones Turbulene models: Spalart-Allmaras - ε Realizable, SST -ω, Define material properties Provide initial values or a previous solution Set up solver ontrols Post-Proessing Examine the results to review solution and extrat useful data Numerial Reporting Tools an be used to alulate quantitative results Fig.. Sheme of proess to simulate onsidered model... Boundary and Initial Conditions In this investigation, onsidered isolate is supposed to have: Smooth surfae (ignoring the surfae roughness). Isothermal (exepted for heat transfer between plane and environment) The flow around arried out at AOA and the free stream with Mah number ranged from.6 to.

3 Automation, Control and Intelligent Systems 15; 3(6): at an averaged Reynolds number of 5.e5 5.e5. The wind tunnel operates at approximately L H W= ( 1b 15b) ( 6b 8b) ( 6b 1b) for subsoni and L H W= ( b 7b) ( 1b 3b) ( 1b 3b) for supersoni.3. Turbulent Model Within the sope of this problem, we use the equation of state based on the ideal gas model. Then: For inompressible gas flow: 1 ρ= ρspe= onst; dh= pdt+ dp; ρ ( ) = T ; = R p p p v or ompressed air lines are: pabs ρ = ; dh = pdt; p = p ( T ); p v = R RT When onduting the alulation, we an hoose the expression depends on the temperature of the heat apaity at onstant pressure, aording to the methods already p available to support the follo: Perfet Calorially p= onst Multi-standard mode or Zero Pressure NASA Format [1]. For a three dimensional, steady, inompressible, and turbulent visous flow, the mass and momentum equations ould be written in the Reynolds-Averaged Navier-Stoes: ρ Continuity equation: + ( ρui) = t x Momentum onservation equation: ( ρu) i + ( ρuu i ) = t x i {( τ ρuu )} p = + + S x x Conservation equation of total energy ( ρh ) tot p + ( ρuhtot) = t t x i i M T µ t h = λ + + ( u ( τi ρuu i )) + x x Prt x x + u S + S M E Here: p Pressure has been adusted, taing into aount elements of pressure aused by the turbulent ineti energy and the effetive visosity: p = p+ ρ + µ U 3 3 eff τi stress tensor: u τ i= µ eff Si δ i 3x S, δ respetively, and strain rate tensor funtion i i Kroneer funtion: S i 1 u u 1 i i ; δ = = i + = x x i i ρuu i Reynold stress odes. In theory, the eddy visosity Reynolds stresses depends on the average veloity gradient and diffusion gradient swung by the follo expression: u ρ uu = µ S µ ρ δ 3 + x i t i t i µ eff the atual visosity of the flow. µ eff quantity is determined by the formula: µ eff= µ + µ t µ visosity is determined aording to the formula on the basis of the model is supported by ANSYS. CFX suh as Ideal Mixture, Non-Newtonian Model, Sutherland's Formula µ t turbulent visosity (or visosity vortex) generated by the turbulene and is determined aording to the formula depending on the model of turbulene that we hoose. In the solution of the onservation equations, the turbulene term should be replaed by suitable equivalent model; otherwise, the equations are not solvable. The model used to solve the simulation is SST ω. The SST ω turbulene model is a two-equation eddy-visosity model that is used for many aerodynami appliations. It is a hybrid model ombining the Wilox -omega and the -epsilon models. GAMBIT -4.6 and ANSYS. CFX 1.1 are used for modeling and simulation respetively. 3. Semi-empirial Method 3.1. Determine the Lift Coeffiient When small angle of atta and angle helial α 1; δ= twisted is the lift oeffiient depends on angle of atta is almost linear. Therefore, the lift oeffiient an be expressed as follows [5]: y1. α α y. = y. α= y x. α α partial lifting fore oeffiient y1. aording to the angle of atta in the oordinate system Ox1y1z1. α y1. depending on the number M and shape on plane : elongation λ, spasm of s η and s orner χ. - relatively thi profile, as

4 11 Nguyen Quang Vinh: Determination of the Aerodynami Charateristis of Flying Vehiles Using Method Large Eddy Simulation with Software ANSYS measured in setion parallel to the plane symmetry of flying mahines. The dimensionless quantity is determined aording to the follo formula: b l = λ= b b S. = ; η ; 4. Results and Disussion The simulated results are obtained using numerial simulation with software paage ANSYS. CFX and GAMBIT. The Fig. 3 to Fig. 6 are the plots of the pressure ontour effort to surfae with different Mah numbers. α y1. - defined by the expression [4, 5]: ( λ 1 ; λ χ,5; λ ) α y 1. 3 λ = f M tg x. oeffiient of drag, lift the front as zero 3.. Identify the Front Drag Coeffiient Resistane oeffiient frontally x. is defined by the expression [4, 5]: = + x. x. xi.. xi. indued drag oeffiient, whih is generated by the lift, whih is determined by the formula: Fig. 3. Pressure ontour at M =.8. α ( αα 57,3ξ αα) = K α xi. y. F y. α 57,3 Kαα, αα interferene oeffiient between the s and fuselage. In isolated ases Kαα= αα= 1. ξ its orresponding absorption oeffiient and its F, effiieny oeffiient. For s with sharp edges before then F= ξ=. x., ode for the next ase without ail after, whih is determined by the formula [4.5]: == + x. xp. xb. xp. oeffiient of drag aused by the visosity of the gas stream to flow. This oeffiient is determined by the = f η η. follo formula: ( ) η, η, ( f) = M M xp. M= M is determined aording to experimental results in [4,5]. A oeffiient of drag aused by the xb. ompressibility of the flow. The value of this oeffiient, depending on the Mah number, the plane shape, thiness ontour and shape, whih is determined from the expression dependent [4, 5]: Fig. 4. Pressure ontour at M = 1.. xb. λ M 1 ; λtgχ; = f λ η ; ' s profine Results determined oeffiient method and empirial theory is presented in the form of graphs in the doument [5]. Fig. 5. Pressure ontour at M = 1.5.

5 Automation, Control and Intelligent Systems 15; 3(6): Fig. 6. Pressure ontour at M =...45 Drag oeffiient as a funtion of Mah number.4.35 Cd_sim Cd_analyt.3.5 Cd Mah number Fig. 7. Variation of drag oeffiient as funtion of M The lift oeffiient as a funtion of Mah number Cl_sim Cl_analyt Cl Mah number Fig. 8. Variation of drag oeffiient as funtion of M.

6 13 Nguyen Quang Vinh: Determination of the Aerodynami Charateristis of Flying Vehiles Using Method Large Eddy Simulation with Software ANSYS In Fig. 3 to Fig. 6 an be observed that the total pressure inreases when Mah number inreases from.5 to about 1., and dereases when the Mah number is over 1. Figure 7 are sho the results of the drag, lift oeffiients at AOA and the Mah number varies in the range from.6 to.5, respetively as obtained from the analytial and numerial simulation. Quite good agreement between the analytial and numerial results ould be realized. The variation of the lift oeffiient between the analytial and numerial simulation ause the assumption we have represented above (inlude smooth surfae, isothermal...). 5. Conlusions The ollision phenomena with influene on the aerodynami harateristis of isolate operation were investigated analytially and numerially. On the numerial part, the onservations of mass and momentum equations are solved by software paage ANSYS. CFX using finite volume tehnique. To lose the domain, the turbulene part of the flow is approximated by using SST ω model. The aerodynami parameters, lift, drag oeffiients were measured analytially and predited numerially at and various Mah number in the range from.6 to.5. The results are ompared with the analytial method and good agreements is ahieved. Anowledgements The authors would lie to than olleagues in Vietnam Aademy of Military Siene and Tehnology for their assistane during the use of ANSYS s laboratory to produe the model. Referenes [1] Ansys. CFX Release 1.: ANSYS CFX-Solver Theory Guide. [] Ansys. Gambit Helps. [3] Zaharheno VF, et al., Determination of total aerodynami harateristis of various onfigurations of airraft. M: Publishing house of the MSTU. Bauman, [4] AA Lebedev, Chernobrovin LS Flight Dynamis: unmanned aerial vehiles. M: Mehanial Engineering, [5] Proess and researh on the method of guidane a maneuvering target with sholasti predition about its motion and with nonlinearities in the ontrol irle (A report on the sientifi researhing wor)/mstu named after Bauman. The supervisor: Pupov K. A. The exeutors: Nguyen Quang Vinh, Bobov A. V., Ustiuzanin A. D. / Mosow, 6, 75 pages.