M. M. Dhongadi ¹, K. V. Sreenivas Rao ², G. R. Srinivas ¹

Affiliations
1 Dayananda Sagar College of Engineering, Bangalore– 560078, Karnataka, IN
2 Siddaganga Institute of Technology, Tumkur– 572103, Karnataka, IN

Abstract

Flow at inlet of fan in an axial compressor must be one dimensional as developed flow so that angular momentum fed by the fan to incoming air is maximum. It is possible with good inlet design and optimum inlet length where we obtain stream line flow into fan with nominal boundary layer thickness. Distortion to the flow at fan inlet in an axial compressor is unavoidable problem. For example in aircraft gas turbine engine; flow at inlet of fan is distorted due to maneuvering of air craft, strong cross winds and atmospherics turbulence at inlet of compressor. Flow at inlet of fan affects boundary layer and hence the performance of compressor. Therefore, visualization of flow with boundary layers in an axial ducted fan setup is carried out for well-defined inlet conditions using pressure probes. To visualize the flow with boundary layer development at the fan inlet, static and stagnation pressure are measured throughout the inlet passage of duct using static and pitot probe and velocity is calculated across the given reference planes of duct using Bernoulli’s equation. Using these data, profile plots are drawn and mathematical models are developed and flow with boundary layer is analyzed. Under normal inlet flow condition flow in the duct inlet is axisymmetric, steady, turbulent and incompressible. Boundary layer develops consistently towards the fan inlet and it is nominal.

Keywords

Axial Compressor, Boundary Layer, Flow Visualization, Pressure Probes.

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Hanumanthu ¹, K. V. Sreenivas Rao ²

Affiliations
1 Thermal Power Engineering, SIT, Tumkur – 572103, Karnataka, IN
2 Department of Mechanical Engineering, SIT, Tumkur – 572103, IN

Abstract

Most of airplane structures include the components such as Fuselage, Wings, Empennage, Landing gear and Power plant etc. Wings are the important part of aircraft and these are airfoils attached to each side of the fuselage and are the main lifting surfaces that support the airplane in flight. SSD-2 airfoil, a modified version of NACA23015 airfoil is used to study the aerodynamic characteristics such as lift, drag, moment and wall effects with different wind tunnel blockage ratios. Generally, any new airfoil characteristics are derived from the extensive wind tunnel tests, however experiments are costly. Hence, to get the idea of aerodynamic characteristics and wall effects over airfoil with different wind tunnel blockage ratios, CFD tools are used such as ICEM CFD and ANSYS FLUENT. This paper presents the results of simulation of flow past SSD-2 airfoil. The study is carried out on a 2D airfoil section for free stream condition. Further the computations are made on 3D rectangular wing of solid wind tunnel simulation by varying wind tunnel height to get the different wind tunnel blockage ratios, keeping the other parameters constant. In solid wind tunnel simulation the lift and moment are less compared to free stream simulation results due to blockage effects. Finally, it is observed that increase in the wind tunnel blockage ratio, lift and moment decreases, drag increases with less difference in pressure; whereas decrease in wind tunnel blockage ratio, the lift and moment increases, drag decreases with more difference in pressure.

Keywords

Drag, Fluent, ICEM CFD, Lift.

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M. M. Dhongadi ¹, K. V. Sreenivas Rao ², G. R. Srinivas ¹

Affiliations
1 Dayananda Sagar College of Engineering, Bangalore – 560078, Karnataka, IN
2 Siddaganga Institute of Technology, Tumkur – 572103, Karnataka, IN

Abstract

In axial compressor distortion at inlet leads to adverse pressure gradient at inlet of fan which leads to performance degradation and adverse effects like vibration and noise. The major distortion can lead to surge or stall in compressor. Hence, this study involves creating distortions at inlet and studying its effects on stall and performance of compressor fan. To analyze effect of distortion on compressor, an axial ducted fan is used. Study is carried out for normal flow condition, hub distortion and radial distortion conditions. Static pressure is measured in two cases. In first case, for different mass flow rate, difference in the static pressure of fan is measured, for which performance characteristic curves are plotted. In second case, normal flow inlet is distorted at operating point using above said distortion methods and difference in static pressure of fan is measured for which efficiency of fan is calculated. 60% of flow at inlet is blocked in both the cases of distortion by mechanical means using screens. Velocity across the duct at fan inlet is calculated, for which mathematical models are found. From this, average velocity from hub to tip which is necessary to find efficiency is calculated. Study shows amount of distortion not only affects stall and surge margin but also type of distortion affects surge and stall of ducted fan. Radial distortion exhibits less amount of stall margin than hub distortion for same amount of inlet flow.

Keywords

Axial Compressor, Hub Distortion, Radial Distortion, Surge and Stall.

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M. G. Basavaraju ¹, V. K. Venkatesh ¹, K. V. Sreenivas Rao ¹

Affiliations
1 Department of Mechanical Engineering, Siddaganga Institute of Technology, Tumkur - 57210, Karnataka, IN

Abstract

Heat pumps are the most promising technologies to reduce global warming emissions and to more rationally use energy. In this experimental investigation Carbon Dioxide (CO2) was used as refrigerant which is available in nature, eco friendly, economical, non toxic, non flammable and non corrosive. It is The performance evaluation of prototype vapor compression heat pump model was performed and evaluated the different parameters such as LMTD (Logarithmic Mean Temperature Difference), COP (Co-efficient of Performance) and heat transfer rate of condenser. This experiment is carried out by varying water mass flow rate, pressure and evaporator fan speed for two condensers of different dimensional specification. The water in the shell side was heated by absorbing heat from refrigerants in the tube side of condensers by counter flow heat exchanging method. The experimental results indicate fairly good COP with the use of CO2. The advantages of CO2 as refrigerant with zero ODP and minimum GWP.

Keywords

COP, Evaporator, Heat pump, LMTD, Ozone Depletion Potential.

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