Sitki Uslu

Exergy analysis of an air-blasted combustor: an application for atmospheric test rig condition

Combustion of fuel finds its importance in heating, power production and transportation. The main objective of this study is to assess the performance of an air-blasted combustor using the exergy at different combustor exit temperatures (T4). Exergetic metrics of the combustor in a test rig were made between 1,100 < T4 ≤ 1500K. JP8 kerosene-type fuel was used for analysis. For the combustor, exergy efficiency was calculated to be between 49.3% and 59.4%. Furthermore, greatest exergy destruction is found at highest combustor exit temperature (138.7 kW at 1500 K), while the lower exergy destructions are found at 1102 K with the value of 90.7 kW. The methodology and the results of this study can be beneficial for further improvement, and development of similar combustor systems for designers.

Exit Temperature Profile Measurement and CFD Comparisons on Small Scale Turbojet Combustor with Air Blast Atomizer Configuration

Small scale turbojet engines are used in miniature UAVs and target drones. Combustor design at this scale is a challenge due to reduced volume for atomization, mixing and subsequent combustion. Furthermore correct estimation for the engine lifetime is critical in the design phase. In terms of lifetime hot-section components are much more critical. Exit temperature profile, which is commonly quantified using radial temperature distribution factor or using overall temperature distribution factor, is critical for the lifetime determination of critical hot-section engine components such as the first stage inlet guide vane of the turbine. This study presents the viability of the CFD approach for combustor design in terms of comparisons with experimental results put a spotlight to the areas that should improve in order to develop better CFD methods and practices. Results indicate that significant variability might occur even with the slightest manifold design modification. Also injector-to-injector flow rate variability has an effect on the exit plane temperature

Unsteady RANS for Simulation of High Swirling Non-Premixed Methane-Air Flame

Highly swirled non-premixed methane-air combustion is studied using Unsteady RANS. The increased CPU power at present times makes RANS solutions a viable design methodology for industrial applications. LES, Large Eddy Simulation, is still a bit far away from being the routine approach as a design tool in industry. The confined non-premixed TECFLAM S09C flame is investigated because of its similarity with gas turbine engine combustors. A block structured hexahedral computational mesh is used for the whole domain for higher numerical accuracy. A first-order accurate Euler Implicit technique is used for the temporal discretization of the transient terms. Realizable k-e turbulence model is employed in order to account for the turbulent flow effects on the flow field and chemical reactions. Results of fast and two step reactions are compared with finite rate chemistry. Results show that, the best solution is obtained by using Finite Rate Eddy Dissipation Model. The infinitely fast chemistry approach is not capable of predicting the reaction delay that is clearly observed in the experiments. Instead, the fast chemistry approach show reaction zones in the close vicinity of the swirler where the fuel-air mixing is not well achieved for the reactions to take place in such a short distance. The flow field is directly affected by the heat release rate that is determined by the fuel air mixing and combustion model.

Design of a High Pressure Turbine Nozzle Guide Vane with Effective Film Cooling System on Leading Edge

The fast development in the field of aeronautics dictates development of more powerful aircraft engines. Constant increase in overall pressure ratios and operating temperatures are essential for the required higher power and thrust. . However, higher Turbine Entry Temperatures reduce the operation life of engine components. Cooling of engine components is one of the vital issues for development of efficient engines in terms of engine life and cost. Gas turbine cooling technologies have been investigated for more than 70 years and it has substantially changed in the course of new aircraft engine development. In this study, a nozzle guide vane (NGV) is designed and an efficient cooling system is investigated for a commercial aircraft engine NGV leading edge. The engine is developed for “AIAA Undergraduate Team Engine Design Competition” and it has extremely a high overall pressure ratio of 60. The cooling of NGV, Nozzle Guide Vane, is one of the most critical design issues in the whole engine design cycle. In the present study film cooling of an NGV is investigated using computational fluid dynamics (CFD). Parametric study of different cooling hole configurations with a study of different turbulence sub models are studied. The parametric study of film cooling includes the cooling hole types, hole numbers and positions.