STUDY OF HEAT TRANSFER THROUGH RECTANGULAR DUCT IN A GAS TURBINE

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1 International Journal of Mechanical Engineering and Technology (IJMET) Volume 8, Issue 5, May 2017, pp , Article ID: IJMET_08_05_052 Available online at aeme.com/ijmet/issues.asp?jtype=ijmet&vtyp pe=8&itype=5 ISSN Print: and ISSN Online: IAEME Publication Scopus Indexed STUDY OF HEAT TRANSFER THROUGH RECTANGULAR DUCT IN A GAS TURBINE K.Rakesh Sai, D.Gowru Naidu, G.Balu Mahendra, Y.V.Satyanarayana, CH.Siva Krishna Department of Mechanical Engineering, KL University, AP, India. ABSTRACT Gas turbine plays an important role in present day industries. These turbines are being widely used for the generation of power in large scale and also in the aircraft propusion. The main challenge is to increase the performance and efficiency of the gas turbines and this can be done by raising the inlet temperature of the turbine. Now a days gas turbine became more advanced and the inlet temperatures are as high as 17000c, where as the blade materials can withstand a temperature up to 13500c. The compressor in the turbine extracts pressure in the form of a cooling air temperature ranging 6500c. This cooling air is going to pass through the blade airfoil sections to lower the temperature to 10000c which is safe for the operation of engine. The gas turbine blade consists of cooling passages which are very complex, so it is difficult for designers to accurately predict the metal temperature. The aerothermodynamics in these airfoil sections are complex and theree exists a large thermal gradient through out the blade profile and hence the heat transfer coefficients will be high. The heat transfer on the surfaces of the blade passages increases as the flow enters into turbine and accelerates around the blade. For any type of complex flows and high for high inlet temperatures designers need extensive experimental and numerical data to help them in developing efficient cooling techniques. Detailed hot gas path, heat transfer distribution, temperature distribution will help in developing efficient airfoil section profiles. Practically,it is very complex to obtain the experimental data on the heat transfer in thin airfoil sections of the turbine blade. The experiments were carried out on a rectangular duct of aspect ratio 2:1. Air is used as a working fluid. All the analysis part is going to perform in ANSYS Workbench by using Fluent Flow analysis. Key words: Reynolds Number, Nusselts Number, Average Temperatures, Inlet Velocities, Heat Transfer Coefficient. Cite this Article: K.Rakesh Sai, D.Gowru Naidu, G.Balu Mahendra, Y.V.Satyanarayana and CH.Siva Krishna Study of Heat Transfer Through Rectangular Duct in A Gas Turbine. International Journal of Mechanical Engineering and Technology, 8(5), 2017, pp IType= editor@iaeme.com

2 K.Rakesh Sai, D.Gowru Naidu, G.Balu Mahendra, Y.V.Satyanarayana and CH.Siva Krishna 1. INTRODUCTION The purpose of gas turbine technology is to extract the maximum energy from the high temperature high pressure gases produced by combustor. This could be achieved by improving the thermal efficiency of the gas turbine engine. Attempts were being made to increase the power output and thermal efficiency of a gas turbine engine by operating turbine at elevated temperatures as it is understood that the efficiency of gas turbine is a direct function of turbine inlet temperature. Turbine blades are the individual components which make up the turbine section of a gas turbine engine and are responsible for extracting energy from the high temperature, high pressure gases produced by the combustor. The turbine blades are often the limiting component and were considered as the critical components of the gas turbine engines in which failures occur frequently. Gas turbines play a vital role in the today s industrialized society, and as the demands for power increase, the power output and thermal efficiency of gas turbines must also increase. Modern high-speed aero-engines operate at elevated temperatures about 2000 K to achieve better cycle efficiencies. However, the presently available alloys cannot resist temperatures much higher than 1350 K. Internal cooling techniques for gas turbine blades have been studied for several decades. The internal cooling techniques of the gas turbine blade includes: jet impingement, rib tabulated cooling, and pin-fin cooling which have been developed to maintain the metal temperature of turbine vane and blades within acceptable limits in this harsh environment. 2. MODELLING & DESIGNING OF DUCT Modelling and designing are the key elements for any analysis and experimental procedure. This process can be done by using any of the modelling software. Even in analysis software also it is possible to model a simple geometry. In ANSYS workbench we can draw our geometry. Cross section of the rectangular duct is mm length of the duct is 500mm editor@iaeme.com

3 Study of Heat Transfer Through Rectangular Duct in A Gas Turbine 3. EXPERIMENTAL RESULTS Temperature varying with position m Reynolds number 5000 Reynolds number editor@iaeme.com

4 K.Rakesh Sai, D.Gowru Naidu, G.Balu Mahendra, Y.V.Satyanarayana and CH.Siva Krishna Reynolds number Reynolds number

5 Study of Heat Transfer Through Rectangular Duct in A Gas Turbine Table showing the results for our analysis Reynolds number Velocity inlet (m/s) Temperature (K) Heat transfer coefficient (W/(m 2 K) Nusselts number CONCLUSIONS From this analysis we can conclude that as we increase the Reynolds number both the inlet velocities and heat transfer coefficient increases, where as the temperatures decreased. The heat transfer on the surfaces of the blade passages increases as the flow enters into turbine and accelerates around the blade. For any type of complex flows of a turbines and for high inlet temperatures, designers need extensive experimental and numerical data to help them in developing efficient cooling techniques. 5. FUTURE SCOPE Based on our present analysis in future we are going to work on getting some more extensive experimental data such as detailed hot gas path heat transfer distribution, temperature distribution. This will help in developing efficient airfoil section profiles and also we can increase the efficiency of the gas turbine. REFERENCES [1] Han, J.C., Dutta, S., & Ekkad S.V. (2000). Gas Turbine Heat Transfer and Cooling Technology, Taylor & Francis, New York (ISBN X). [2] Von Karman Institute for Fluid Dynamics, Heat Transfer and Cooling in Gas Turbine, Lecture Series , May [3] Çengel, Y. A. and Turner, R. H. (2001). Fundamentals of Thermal-Fluid Sciences, McGraw-Hill Companies, New York (ISBN ). [4] Lectures from NPTEL. [5] Prabhat Kumar Sinha, Rajneesh Pandey And Vijay Kumar Yadav Analysis And Modeling Of Single Point Cutting(Hss Material) Tool With Help Of Ansys For Optimization Of (Transient) Vibration Parameters, International Journal of Mechanical Engineering and Technology, 5(6), 2014, pp [6] Praveen Padagannavar and Manohara Bheemanna,Automotive Computational Fluid Dynamics Simulation of A Car Using Ansys International Journal of Mechanical Engineering and Technology, 7(2), 2016, pp [7] Janvijay Pateriya, Raj Kumar Yadav, Vikas Mukhraiya and Pankaj Singh, Brake Disc Analysis with the Help of Ansys Software. International Journal of Mechanical Engineering and Technology, 6(11), 2015, pp editor@iaeme.com

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