Fig 2: Grid arrangements for axis-symmetric Rocket nozzle.

Transcription

1 CFD Analysis of Rocket-Ramjet Combustion Chamber 1 Ms. P.Premalatha, Asst. Prof., PSN College of Engineering and Technology, Tirunelveli. 1prema31194@gmail.com Ms. T. Esakkiammal, Student, PSN College of Engineering and Technology, Tirunelveli. 2 devswathiraj@gmail.com Abstract--In this paper CFD analysis of pressure and temperature for a rocket Ramjet engine with four inlets and Dual Bell extension is analyzed with the help of fluent software. when the fuel and air enter in the combustion chamber, it is burning due to high velocity and temperature and then temperature increases rapidly in combustion chamber and convergent part of the nozzle and after that temperature decreases in the exit part of the nozzle. It is proposed to perform with four inlets with dual bell rocket nozzle as it has better performance than single inlet and two inlets. The objective of the present work is to simulate supersonic flow through rocket nozzle with combustion chamber to precisely understand the flow dynamics and variation of flow properties in combustion chamber with the nozzle. The paper consists of following three cases. Case 1: Four inlets nozzle. Case 2: Single inlet nozzle. Case 3: Four inlets with Dual bell. This simulation is carried out using ANSYS work bench and Fluent software. ANSYS Workbench is used for generating the required mesh and simulation is to be done using fluent. Keywords: Rocket Engine; Ramjet Engine; CFD; Dual Bell Nozzle; ANSYS. 1. INTRODUCTION A ram jet engine is a device from which useful thrust can be obtained by creating a velocity difference between the atmosphere entering the ram jet body and the same quantity of air leaving the ram jet body. This velocity difference between entrance and exit air is accomplished by the addition of heat to that portion of the airstream flowing through the ram jet body. Burning liquid fuel inside the ram jet body is one means of adding heat to a ducted airstream and is the only method with which this monograph will be concerned. The ram jet engine is composed of three major components: a body structure, fuel injection system, and a flame stabilization system. A poor design of any one of these parts will nullify a good design of the other components. In order to build a good performing engine all three components must be of proper design because of their close relation and dependence upon each other. Fig 1: Dual Bell Nozzle. 2. GEOMETRY AND GRID ARRANGEMENT A 2D axis- symmetric computational domain was considered, the initial design parameters for De Laval nozzle with combustion chamber for Mach number 2.1 with combustion chamber. Fig 2: Grid arrangements for axis-symmetric Rocket nozzle. 1

2 3. THEORETICAL APPROACH The theoretical approach of nozzles is carried out and the models of nozzles namely the full length Dualbell nozzle created using Fluent, Gambit software. The next step goes to the meshing and analysis of the dual bell model using FLUENT software. The behavior of flow along the dual bell nozzle is thus obtained and comparison on the basis of Mach number is henceforth done using theoretical calculations 5.2: CASE 2 SINGLE INLET 4. FLOW ANALYSIS The flow analysis for the dual bell nozzle is carried out using ANSYS 14.0 Fluent software. In this process first the models are imported, meshed and flow analysis is carried out in major three steps; 1. The first step is ANSYS WORK BENCE, where the meshed model is imported and boundaries are created and corresponding boundary conditions are assigned to the boundaries. 2. The second step is FLUENT-SOLVER, where the solutions are obtained by solving the equations and process is highlighted in terms of codes and graphs and once the run is over it reaches next step. 3. The third step is FLUENT, where the corresponding contours are created for following major parameters such a Pressure, Temperature and Mach number. 5. MODELING 5.1: CASE 1 FOUR INLET 5.3: CASE 3 FOUR INLET DUAL BELL 6. RESULTS AND DISCUSSION 6.1: CASE 1 - FOUR INLET In case 1 four inlet nozzle is considered. The analysis is done in Fluent and the results are shown. As said above in nozzle design the dual bell nozzle is modeled and is further meshed using ANSYS 14.0GAMBIT Software. The mesh is of unstructured type. 2Dmesh contains triangular elements and the 3D mesh contains tetragonal mesh elements. Dimensions in m Fig 6.1.Meshed geometry 2

3 6.2: CASE 2 - SINGLE INLET In case 2 single inlet nozzle is considered. Figure.6.1.1Static Pressure Figure.6.2.Static Pressure Figure Static Temperature Figure Static Temperature Figure velocity magnitude Figure velocity magnitude 3

4 6.3: CASE 3: FOUR INLET WITH DUAL BELL In case 3 four inlets with Dual Bell nozzle is considered. Figure velocity magnitude Fig6.3. Dual Bell Meshed geometry 7. TABLE: CFD RESULTS COMPARISON Figure Static Pressure Figure Static Temperature Parameters Static Pressure (Pa) Static Temperature (K) Velocity magnitude (m/s) CASE 1 FOUR INLET CASE 2 SINGLE INLET CASE 3 DUAL BELL Throat Outlet Throat Outlet Throat Outlet -2.83e3-5.88e2-1.46e5 1.64e4-9.97e e2 6.6e2 5.25e2 6.5e2 8.7e2 6.15e2 4.35e2 1.54e2 4.61e1 6.32e2 1.26e2 1.78e2 1.98e1 The Results of CFD analysis was compared for three cases at throat and outlet. The static pressure at throat is minimum in Dual bell system. The pressure of e-3 Pa is maintained in the Dual Bell system throat which is lesser than both the conventional type of combustion chambers. The static temperature is higher in case 1 four inlet system. The combustion outlet temperature is minimum in dual bell system which was 435K. The turbulent kinetic energy is higher in dual bell system than other cases. The density of fluid is minimum at the throat of dual bell system. The turbulent intensity at the throat of the dual bell system is higher. The radial velocity at the outlet of the dual bell system is lesser than other cases. The velocity magnitude at the outlet of the dual bell system is lesser than other cases which has higher performance. 4

5 8. CONCLUSION In this paper Computation Fluid Dynamics analysis of Rocket combustion chamber is performed by using ANSYS Workbench and FLUENT software. The Four inlet rocket nozzle has better performance than single inlet and two inlets. In this present work the simulation of supersonic flow through rocket nozzle with combustion chamber to precisely understand the flow dynamics and variation of flow properties in combustion chamber with the nozzle is studied. This simulation result shows that the Dual Bell nozzle with four inlet system has better performance that convention type of combustion system. REFERENCES 1. Altman, D, Hybrid Rocket Development History, 27th Joint Propulsion Conference, , AIAA, Sacramento, CA, 1991, pp J. P. Arves, H. S. Jones, K. Kline, K. Smith, T. Slack, and T. Bales, Development of a N20/HTPB Hybrid Rocket Motor, 33rd Joint Propulsion Conference, , AIAA, Seattle, WA, 1997, pp J. P. Arves, H. S. Jones, K. Kline, K. Smith, T. Slack, and T. Bales, Overview of Hybrid Sounding Rocket Program, 33rd Joint Propulsion Conference, , AIAA, Seattle, WA, 1997, pp J. P. Arves and H. S. Jones, A Standardized Technique for Evaluating Hybrid Rocket Motor Performance, 33rd Joint Propulsion Conference, , AIAA, Seattle, WA, 1997, pp T. A. Boardman, T. M Abel, S. E. Claflin, and C. W. Shaeffer, Design and Test Planning for a 250-KLBF Thrust Hybrid Rocket Motor under the Hybrid Propulsion Demonstration Program, 33rd Joint Propulsion Conference, , AIAA, Seattle, WA, 1997, pp C. Carmicino, and A. Russo Sorge, Investigation of the Fuel Regression Rate Dependence on Oxidizer Injection and Chamber Pressure in a Hybrid Rocket, 39th Joint Propulsion Conference, , AIAA, Huntsville, AL, 2003, pp Hollman, S., L. Frederick, R. A., Jr., Labscale Testing Techniques for Hybrid Rockets, AIAA , W. T. Horton, P. J. Mueller, and F. J. Redd, UTAH-X Utah s Third Advanced Hybrid Experiement, 32nd Joint Propulsion Conference, , AIAA, Lake Buena Vista, FL, 1996, pp R. W. Humble, M. P. Bettner, and R. A. Sandfry, Hystar Hybrid Rocket Program at The United States Airforce Academy, 33rd Joint Propulsion Conference, , AIAA, Seattle, WA, 1997, pp R. Kannalath, A. Kuznetsov and B. Natan, Design of a Lab-Scale Hydrogen Peroxide/Hydroxyl Terminated Polybutadiene Hybrid Rocket Motor, 39th Joint Propulsion Conference, , AIAA, Huntsville, AL, 2003, pp