Space subsystems design: (navigation, control, structure and…)
Morteza Tayefi; Ramin Kamali Moghadam
Volume 15, Issue 3 , September 2022, , Pages 1-9
Abstract
To create drag and reduce the speed of space payloads in the phase of entering the atmosphere, the payload body itself can be used as brake mechanisms without using additional tools. The approach analyzed in this paper is the separation of the nose and then the stability of the cylindrical body in horizontal ...
Read More
To create drag and reduce the speed of space payloads in the phase of entering the atmosphere, the payload body itself can be used as brake mechanisms without using additional tools. The approach analyzed in this paper is the separation of the nose and then the stability of the cylindrical body in horizontal or vertical mode. First, by numerical solution, the cylindrical body is aerodynamically simulated in the flight conditions entering the atmosphere, and the location of the center of mass is designed to achieve static stability. Then, by developing the equations of motion of atmospheric reentry using aerodynamic coefficients and derivatives calculated by DATCOM, the flight parameters for both modes are compared and evaluated. The simulation results show that the horizontal flight is more efficient and is able to create better conditions for opening the parachute and landing. Another advantage of atmospheric reentry flight in horizontal mode is the proper distribution of aerodynamic heating and reduction of heat load in certain points of the payload.
Space systems design (spacecraft, satellites, space stations and their equipment)
Ramin Kamali Moghadam; Mohammad Taeibi Rahni; Salar Heyat Davoudian; Reinhard Miller
Volume 15, English Special Issue , May 2022, , Pages 25-33
Abstract
Superhydrophobic coatings can be made by creating a micro-sized structure on a surface providing super-repellent properties which has many applications in aerospace, defense, automotive, biomedical and engineering. Numerical simulation of drop dynamics and motion on a superhydrophobic surface helps us ...
Read More
Superhydrophobic coatings can be made by creating a micro-sized structure on a surface providing super-repellent properties which has many applications in aerospace, defense, automotive, biomedical and engineering. Numerical simulation of drop dynamics and motion on a superhydrophobic surface helps us understand control and building surface textures and find optimum micro structured coatings of maximum hydrophobicity. In the present work, the dynamics of drops on superhydrophobic inclined micro-structured surfaces is studied, using a finite element method. Effect of microstructures on droplet behavior on a superhydrophobic surface is investigated using different microstructures. The governing equations and important dimensionless numbers are described and a numerical algorithm is introduced. The validation of the numerical algorithm is performed by simulation of drop motion attached to an inclined surface. In addition, droplet movement on the micro structured surface is numerically simulated on smooth and microstructure surfaces in the same conditions. Comparison of the results shows the effect of microstructure coating on the surface hydrophobicity properties.
Ramin Kamali Moghadam; Mohammad Reza Salimi
Volume 8, Issue 4 , January 2016, , Pages 19-27
Abstract
An accurate and efficient computational procedure is developed to predict the laminar hypersonic flowfield for both the perfect gas and equilibrium air around the axisymmetric blunt body configurations. To produce this procedure, the boundary layer equations utilize the integral matrix solution algorithm ...
Read More
An accurate and efficient computational procedure is developed to predict the laminar hypersonic flowfield for both the perfect gas and equilibrium air around the axisymmetric blunt body configurations. To produce this procedure, the boundary layer equations utilize the integral matrix solution algorithm for the blunt nose and after body region by using a space marching technique. The integral matrix procedure enables us to create accurate and smooth results using the minimum grid in the boundary layer and to minimize the computational costs. This algorithm is highly appropriate for the design of hypersonic reentry vehicles. The effects of real gas on the flowfield characteristics are also studied in boundary layer solutions. Comparisons of the results with experimental data demonstrate that accurate solutions are obtained.
R. Kamali –Moghadam; S. Nouri; M. R. Salimi; M. Sheida; S. A. Hosseini
Volume 6, Issue 3 , October 2013, , Pages 39-48
Abstract
When a solver is used for analyzing the hypersonic reentry vehicles, high speed and accuracy of the solver results are the basic parameters in the design process. In the present study, the results obtained by solution of laminar boundary layer equations using integral matrix method and approximate method ...
Read More
When a solver is used for analyzing the hypersonic reentry vehicles, high speed and accuracy of the solver results are the basic parameters in the design process. In the present study, the results obtained by solution of laminar boundary layer equations using integral matrix method and approximate method are assessed in aeroheating prediction around hypersonic axisymmetric reentry bodies. The results show that the applied methods have suitable accuracy in aeroheating and high computational speed for reentry vehicle design. Space marching method in numerical simulation of boundary layer equations and applying less grid point in the boundary layer due to use of integral matrix method rather than other methods efficiently decrease computational costs. Also, high robustness of approximate method in the heat flux prediction over the reentry surface makes it useful for design process.Using a special approximate relation for stagnation region improves the aero-thermodynamics results.
