Assessment of airfoil aerodynamic characteristics is essential part of any optimal airfoil design procedure. This paper illustrates rapid and efficient method for determination of aerodynamic characteristics of an airfoil, which is based on viscous-inviscid interaction. Inviscid flow is solved by conformal mapping, while viscous effects are determined by solving integral boundary layer equations. Displacement thickness is iteratively added to the airfoil contour by alternating inviscid and viscous solutions. With this approach efficient method is developed for airfoil design by shape perturbations. The procedure is implemented in computer code, and calculation results are compared with results of XFOIL calculations and with experiment. Eppler E387 low Reynolds number airfoil and soft stall S8036 airfoil are used for verification of developed procedure for Reynolds numbers 200000, 350000, and 500000. Calculated drag polars are presented in this paper and good agreement with experiment is achieved as long as small separation is maintained. Calculated positions of laminar separation, reattachment, and turbulent separation closely follow experimental measurement. The calculations are performed in relatively short time, which makes this approach suitable for low Reynolds number airfoil design.

This study highlights the mechanism of formation for Bentonite clay surface properties. It investigates specific gravity and the influence of physicochemical characteristics on clay stability of structural forces on adsorbed water molecules. In particular, it describes the chemical composition, as well as cation exchange capacity (CEC). Bentonite clay is collected from the Murzuq city located 1150 km south of Tripoli i.e. southernmost town of Libya. The CEC value is leached by 500ppm Ca+2 at pH=8 equaled 84.5 mmoles/kg. While at pH=2, the value is (20.5 mmoles/kg). The leaching process is carried out by 500ppm K+ using flame emission photometer. The CEC value at pH =8 for sample is 91.5 mmoles/kg. Also the specific gravity is found to be 2.597. This value is in agreement with the obtained standard values for Wyoming (USA). The % MxOy of the clay is calculated by gravimetric method as follows: SiO2, 53.75; Al2O3, 21.46; Fe2O3, 1.4;CaO, 0.97; MgO, 2.13, and agreed with the XRF analysis as follows: SiO2, 54.93; Al2O3, 21.46; Fe2O3, 1.71; MgO, 3.18 ; CaO, 0.81; Na2O, 5.48; K2O, 0.54; TiO2,0.32. The results are adequately approximate and reasonable for both methods. The percent is very limited for trace elements Pb, Cr, Cd, Cu, Fe, and Zn. In the sample, it is about 0.21%. The result of XRD analysis (intensities) for sample is presented as follows: 50% quartz, 50% kaolinite, 5% Analcine, 7.5% Illite, 5% Natrolite, 10% Nontronite, 7% Montmorillonite. The formula calculation depends on the purity of clay and consequently the structural formula for Libyan Bentonite is: K0.094Na1.45Ca0.118 (Al2.92Fe0.175Ti0.033Mg0.646)VI( Al0.52Si7.48 …

The main objective of the paper is to analyze the performance of axial flow compressors and to generate a systematic design approach which enables to design subsonic flow ones. In order to investigate the validity of this approach, the LP axial flow compressor of the RR Spey MK511 turbofan engine is taken as an example. The design calculations were based on thermodynamics, gas dynamics, fluid mechanics and empirical relations. The flow is assumed to be of two-dimensional compressible type with constant axial and rotor blade velocities with a free-vortex swirl distribution. Design calculations include

thermodynamic properties of the working fluid, number of compressor performance parameters such as, stage temperature rise and number, flow and blade angles (blade twist), velocity triangles and relative inlet Mach number at rotor blades tips as well as blades tip and hub diameters. A repeated calculation is made to determine these parameters along compressor stages. The variation of velocity whirl components, air and blade angles, deflection and degree of reaction from root to tip of the blades were also determined. The twist of the blades along the blade length is set according to the recommended values in order to obtain smooth blade twist profile.