AEROTHERMODYNAMIC TOPOLOGY OPTIMIZATION OF HYPERSONIC RE-ENTRY VEHICLE WITH AEROSPIKE BY USING CFD

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1 International Journal of Mechanical Engineering and Technology (IJMET) Volume 9, Issue 1, January 2018, pp , Article ID: IJMET_09_01_119 Available online at ISSN Print: and ISSN Online: IAEME Publication Scopus Indexed AEROTHERMODYNAMIC TOPOLOGY OPTIMIZATION OF HYPERSONIC RE-ENTRY VEHICLE WITH AEROSPIKE BY USING CFD Harish Panjagala Faculty of Mechanical Engineering, Koneru Lakshmaiah Educational Foundation, Vaddeswaram, Guntur, Andhra Pradesh, India E L N Rohit Madhukar, I Ravi Kiran, V Shashank, Sai Venkata Bharadwaj UG Scholar, Department of Mechanical Engineering, Koneru Lakshmaiah Educational Foundation, Vaddeswaram, Guntur, Andhra Pradesh, India ABSTRACT Due to increasing demand of High Speed reentry vehicles for Space activities in the world, a major issue related to the process of slowing down a body is by the formation of stronger shocks that leads to extreme heat generated at the nose. The cost of thermal protection systems generally used to reduce the heat in the reentry vehicles is very high. So, there is a need of study to reduce aero heating in space vehicles. In this paper the eventual outcome is to reduce the aero heating, it is achieved by introducing a spike at frontal region of the nose. In addition, this spike is also used in avoiding the damage and preserving the structural integrity of vehicle over elevated temperatures. Further, by changing the geometry of the tip of spike yielded some better results. Hence, we suggest usage of spike in reentry vehicles is the most effective and economical over other protection systems. Key words: Heat generation, Thermal protection, Reentry vehicle, Aero-Heating, Spike, Structural integrity. Cite this Article: Harish Panjagala, E L N Rohit Madhukar, I Ravi Kiran, V Shashank, Sai Venkata Bharadwaj, Aerothermodynamic Topology Optimization of Hypersonic Re-Entry Vehicle with Aerospike by using CFD, International Journal of Mechanical Engineering and Technology 9(1), 2018, pp INTRODUCTION Winged flight vehicles are generally designed & manufactured with blunt noses. Co-efficient of heat & pressure loadings are often more at the vehicle nose, and a large radius at the nose helps to withstand, distribute, and dissipate these loads. Understanding, analyzing and predicting high speed flow around blunt bodies thus poses a practical and important editor@iaeme.com

2 Aerothermodynamic Topology Optimization of Hypersonic Re-Entry Vehicle with Aerospike by using CFD engineering problem; faster and better design of new flight vehicles depends on it. Referring to the role of wind tunnels in fluid dynamical studies, in 1946 von Neumann Said Indeed, to a great extent, experimentation in fluid dynamics is carried out under conditions where the underlying physical principles are not in doubt, where the quantities to be observed are completely determined by known equations. Thus wind tunnels, for example, are used at present, at least in part, as computing devices to integrate the PDE's of fluid dynamics. F.F.J. Schrijer, F. Scarano & B.W. van Oudheusden [1] was conducted an experiment on Separation of Boundary Layer and Reattachment on a Blunted Cone-Flare using QIRT. Transient HT measurements have been carried out on a blunted cone flare model in a short duration hypersonic facility at Mach 9 using quantitative infrared thermography (QIRT). The surface temperature was measured using an infrared vision camera and the temperature data were successfully correlated to heat transfer co-efficient using two distinct reduction techniques. Z. Jiang, Y. Liu & G. Han [2] was conducted an experiment to achieve effective wave for reducing the drag under non-zero attack angles and also to avoid from severe aero heating, a new concept of the Non-ablative TPS for hypersonic vehicles was first proposed and blunt spike is combined with lateral jets for developing a reconstructing system of shock at front side of hypersonic vehicles. The spike works as recast of the bow shock at front portion of a blunt vehicle, the lateral jet works to reduce the aero heating at the tip of spike and push the shock in conical form away from the blunt body. The experimental visualization of flow & pressure measurements was conducted in a hypersonic wind tunnel for both the conceptual demonstration and CFD validation. D. Dirkx & E. Mooij [3] was investigated the conceptual design of a re-entry vehicle, by varying the vehicles shape and geometry and evaluated its impact on performance. They studied the two classes of shape optimization in vehicles, one is capsule and other one is winged vehicle. By using the local-inclination methods aerodynamic characteristics of those vehicles were analyzed. Entry trajectories at Mach 3 were calculated by assuming trimmed conditions. It has also been studied that based on the geometry of the structure there is significant drop on pressure and temperature of anybody travelling in compressed medium but at stagnant point at which the structure is changed between slendered nacile and again compared to a blunt nacile based on the work of P. Harish et al [4]. It has been studied that there is an important role of temperature in supersonic and hypersonic travel because of compressible effects and the thermal load reduction methods such as counter flow ejection of fluid jet of lower temperature as one of the precautionary measure based on the work of Y.Y. Zeng et al [5]. It was also studied that there is the sudden change of properties in fluid at the nacile portion of the re-entry vehicle due to operational velocity and a range of shocks such as bow shock in frontal end of the vehicle. This situation is analyzed with and without spike and compared with noting of pressure drop in spiked vehicle based on work of C. Nataraj et al [6]. In this work, a blunt reentry vehicle is modelled in Solid works 2016 and analysed in ANSYS Fluent Validation is performed with the obtained CFD results with the experimental values of F.F.J. Schrijer et al [1].Next, optimisation is carried out by placing spikes at the front of the blunt body. Flow analysis is performed using the validated inputs. The main results of the simulation are discussed and compared with the vehicle without spike editor@iaeme.com

3 Harish Panjagala, E L N Rohit Madhukar, I Ravi Kiran, V Shashank, Sai Venkata Bharadwaj 2. MODELING AND ANALYSIS 2.1. Modelling by using Solid Works 2016 Software A 2D DART model has been drafted in solid works as shown in fig For the analysis, the model is imported to ansys fluent solver. DART (Delft Aerospace re-entry test vehicle) is a re-entry vehicle designed at TU Delft. This model was developed with an intension to collect aero thermodynamic flight data and tested for its innovative thermal protection systems. A 3D model of the re-entry vehicle as shown can be created by revolving the drafted 2D model about a particular axis. However, the re-entry vehicle is an axisymmetric body, the analysed results for 2D model is therefore sufficient to verify the entire 3D model. Figure D geometry of blunt body Figure D model of blunt body 2.2. Meshing by using Ansys Fluent 17.2 A Domain has been created near the vicinity of the vehicle (with and without spiked) in the shape of D as shown in the fig This 2D domain provides the information regarding the behavior of air particles (atmosphere) near to the surface of re-entry vehicle editor@iaeme.com

4 Aerothermodynamic Topology Optimization of Hypersonic Re-Entry Vehicle with Aerospike by using CFD Figure Mesh model of blunt body Hybrid meshing is utilized on the model. Most of the space in the domain has unstructured grid. All triangles method is inserted in meshing. Edge sizing and inflation are incorporated to create structured grid around the boundary of the (re-entry) vehicle. The structured grid consists of 5 layers of 1mm thickness each which helps to study the variations in the properties such as temperature, pressure, Mach no etc. near the boundary. The mesh size function is guided by curvature and fine mesh is generated. 2.3 Boundary Condition Calculations After creating and meshing of the Vehicle in ANSYS then we are Exporting the model in to the ANSYS FLUENT 17.2 for the flow analysis for the flowing references. At Mach number (M) =9.1 Gamma ( ) = 1.4 Stagnation pressure= in bar Static temperature=t in Kelvin Stagnation temperature= in Kelvin From Alan-pope formula: = ( ) ( ) = bar (calculate and input into fluent) (1) From Wegener formula p = (T in Rankine) (2) T = (3) T= k (Static temperature, k) = T ( (4) = ( ) = K (Stagnation temperature, k) editor@iaeme.com

5 Harish Panjagala, E L N Rohit Madhukar, I Ravi Kiran, V Shashank, Sai Venkata Bharadwaj 2.4. Flow Analysis using Ansys Fluent 17.2 The results for the Blunt re-entry vehicle are indicated. The temperature values along with corresponding contours and graphs are shown in figures. Figure Temperature Contour of Blunt Body Figure Temperature Plot of Blunt Body We observed that the temperature at the nose for the re-entry hypersonic vehicle was 908 k. 3. VALIDATION AND VERIFICATION The experiment was done at Delft University of Technology, Netherlands. The tunnel was operated at a free stream of Mach number 9.1. The settling chamber of the wind tunnel is pressurized at a total pressure P 0 ranging between 25 and 75 bars. The fluid (dry air) is heated to a temperature of 873 K with a temperature controlled electrical heating system The below figure shows the experimental scleren graph. This graph shows the shock wave pattern and the fluent generated shock wave pattern for the same experimental input so we are comparing the both graphs for validation. Figure 3.1 Comparison of Experimental Result with analytical result editor@iaeme.com

6 C H x 10e3 Aerothermodynamic Topology Optimization of Hypersonic Re-Entry Vehicle with Aerospike by using CFD Figure 3.2. The heat transfers for the experimental model at different Reynolds number with free stream M = Calculation of Heat Transfer Co-efficient (C H ) The Heat Transfer Rate is given by the relation ( ) Where the values of ρ (density), c (specific heat) and l (thickness) of the skin are ρ density of Stainless Steel = 8000 Kg/m3 c specific heat of Stainless Steel = 502 J/Kg K l, thickness of the material = 10 mm and the co-efficient of heat transfer is calculated by using the equation (2) ( (5) (6) Where, ρ, U, and Cp are free-stream density, velocity and specific heat at constant pressure. To is stagnation temperature of the given run and Tw is wall temperature at a given instant time. The below figure shows the graph of experimental as well as fluent generated graph of C H vs. X/L. 8 C H vs X/L Without spike CFD EXPERIMENTAL 0 x/l Figure 3.3 Comparison of Experimental Result with Simulation. From the figure shown in 3.3 we found that deviation between experimental and Simulation results is less than 5%. Hence, the taken case is validated, in order to reduce cost and time we are continuing our simulation in ANSYS FLUENT 17.2 itself editor@iaeme.com

7 Harish Panjagala, E L N Rohit Madhukar, I Ravi Kiran, V Shashank, Sai Venkata Bharadwaj 4. TOPOLOGY OPTIMIZATION From the without spike results, we observed that the temperature at the nose is very high, so that we are concentrating on reducing the Temperature at nose. In order to reduce the nose temperature, we introduced spike for the same model and for same input and successfully found that there is reduction in nose temperature compared to without spike one. Figure 4.1. Blunt Spike Figure 4.2. Slender Spike By varying the shape and geometry of spikes and its impact on performance is evaluated, in this study, the shape optimization of two classes of spikes has been studied: A spike with tip as slender & blunt. On one side, slender spike design reduces the drag but more in aerodynamic heating. On the other side, blunt spike design produces more drag. But they are choosable as aero heating is concerned. To avoid stronger shocks and also for reducing the temperature, spikes are placed at frontal portion of the nose region. Modeling, Meshing & Flow analysis is carried out as same as the without spike model for the same inputs. A spike of two designs was introduced at the nose region of hypersonic winged re-entry vehicle. Blunt spike with entire length 40mm and having blunt radius at tip of 3mm. slender spike of length 40 mm and having slender angle at tip of Figure 4.1. Mesh Model of Blunt Spike Vehicle Figure 4.2. Mesh Model of Slender Spike Vehicle 5. RESULTS AND DISCUSSION 5.1. Blunt Spiked Body For Blunt, spiked body the following pressure profile and Temperature profile is analyzed. Figure Temperature Contour of Blunt Spike Figure Enlarged View of Temperature profile Body editor@iaeme.com

8 Aerothermodynamic Topology Optimization of Hypersonic Re-Entry Vehicle with Aerospike by using CFD Figure Temperature Plot of Blunt Spike Body We observed that the temperature at the nose for the Blunt Spike Re-entry Hypersonic vehicle was 812 k.the shock wave scattered along the length and decreases the temperature along physical domain Slender Spiked Body For slender spiked body Temperature profile is shown below. Figure Temperature Contour of Slender Spike Figure Enlarged View of Temperature Profile Body Figure Temperature Plot of Slender Spike

9 Temperature (K) Harish Panjagala, E L N Rohit Madhukar, I Ravi Kiran, V Shashank, Sai Venkata Bharadwaj We observed that the temperature at the nose for the slender spiked Re-entry Hypersonic vehicle was 848k Position (m) Without spike Blunt spike Slender Spike Figure 5.3. Comparision of Temperature values of without spike and with spiked (Blunt & Slender) vehicles The figure 5.3 shows comparison of temperature values between without spike and with spiked vehicle that includes both Blunt & Slender Spike respectively. The frontal portion (nose) of without spiked vehicle is at a higher temperature than that of its other parts. However, there isn t an appreciable decrease of temperature throughout the body. On the other hand, with spiked vehicles has showed a better response in the reduction of temperature especially at the nose. Moreover, blunt spike vehicle is much more effective than the slender one with some small deviations in there followed path. 6. CONCLUSIONS For many years people are engaged in research to understand the behavior of hypersonic flow. There are still many challenges encountered to carry out analysis and to design these vehicles. In this paper we carried out design and optimization for the re-entry vehicle in hypersonic flight regime at Mach no 9.1. While analyzing both spiked (Blunt & Slender) hypersonic vehicle, as we notice that by introducing the Blunt spike there is 13% reduction of heat at the nose and slender spike is around 7.5 % compared with without spike model. Finally, we conclude that due to spikes there is a heat reduction at nose. When the slender spiked vehicles are comparatively less with Blunt spiked vehicles. So, Blunt spikes are comparatively preferable over slender ones REFERENCES [1] Schrijer Ferry F.J. and Scarano Fulvio and Bas W. van Oudheusden, Hypersonic Boundary Layer Separation and Reattachment on a Blunted Cone-Flare using Quantitative Infrared Thermography, AIAA International Space Planes and Hypersonic Systems and Technology 6967(3), 2003 pp.1-8. [2] Jiang Zonglin and Liu Yunfeng and Han Guilai, A new concept of the Non-ablative Thermal Protection System (NATPS) for hypersonic vehicles, 51(3),2013, pp [3] Dirkx D., Mooij E., Optimization of entry-vehicle shapes during conceptual design, Acta Astronautica 94(1), 2014, pp editor@iaeme.com

10 Aerothermodynamic Topology Optimization of Hypersonic Re-Entry Vehicle with Aerospike by using CFD [4] Harish P., Rajagopal K., Aero thermodynamic Design optimization of a hypersonic winged re-entry vehicle using CFD, International Journal of Engineering and Technology 3(7), 2014, pp [5] Zeng Y.Y and Ahmed N.A., Computational fluid dynamics investigation of counter flow ejection effects on a body moving with high speed, Proceedings International Conference on Mechanical Engineering and Material Science 27, 2012 pp [6] Nataraj C.N. and Manjunatha H., Aerothermodynamic Design and Optimisation of Hypersonic Research Reentry Vehicle, International Journal of Science and Research 3(7), 2014.pp [7] Gnoffo. A Peter, Weilmuenster K. James, H. Harris, Computational Aerothermodynamics design issues for Hypersonic Vehicles, AIAA 36(1), 2001.pp [8] Gnoffo, P. A., Planetary-entry Gas Dynamics, Annual Review of Fluid Mechanics 31(1), 2001.pp [9] Hirschel E.H., Wieland C., Selected Aerothermodynamic Design Problems of Hypersonic Flight Vehicles, International Journal of Computational Fluid Dynamics, 25(10) pp [10] M. Grant, I. Clark, R. Braun, Rapid Simultaneous Hypersonic Aerodynamic and Trajectory Optimization Using Variational methods, Conference AIAA Atmospheric Flight Mechanics, 6640, [11] Kinney D. J., Aero-Thermodynamics for Conceptual Design, 42nd AIAA Aerospace Sciences Meeting and Exhibit, Reno, Nevada, January 2004 [12] Sahoo Niranjan, Saravanan S, Jagadeesh, Reddy K P J, Simultaneous measurement of aerodynamic and heat transfer data for large angle blunt cones in hypersonic shock tunnel, Sādhanā Academy Proceedings in Engineering Sciences 31(5) pp [13] John. D. Anderson, Jr. Computational Fluid Dynamics, McGraw-Hill Book Co., International Editions, pp [14] Versteeg H. K. and Malalasekara W., Introduction to Computational Fluid Dynamics, Long Man Group Ltd., pp [15] =HkshyvPy&hl=en-IN [16] grqid=wi2_szuk&hl=en-in [17] [18] &hl=en-in editor@iaeme.com