Hossein Nadali Najafabadi

Film-Cooling Performance of a Turbine Vane Suction Side: The Showerhead Effect on Film-Cooling Hole Placement for Cylindrical and Fan-Shaped Holes

In this paper, the transient IR-thermography method is used to investigate the effect of showerhead cooling on the film-cooling performance of the suction side of a turbine guide vane working under ...

Towards Efficient CFD-Simulations of Engine LikeTurbine Guide Vane Film Cooling

It is well known that the efficiency of a gas turbine can be increased by using higher combustion temperatures and that this demands improved cooling. This study focuses on strategies to decrease t ...

Film-Cooling Performance of Multiple Arrays of Cylindrical and Fan-Shaped Holes

Experimental investigations are performed on the suction side of a cooled turbineguide vane. Transient IR thermography is used to evaluate film cooling performanceof cylindrical and fan-shaped hole ...

Comparison of Gas Turbine Vane Pressure Side and Suction Side Film Cooling Performance and the Applicability of Superposition

In order to protect a solid surface exposed to high temperature gaseous flows, e.g. gas turbines and rocket engines, a second gas at lower temperature may be introduced into the hot boundary layer, i.e. one obtains a three temperature problem. The impact of the film cooling on a prototype vane due to variation in blowing ratio, the shape of the hole-outlet and position has been experimentally investigated. The semi-infinite and low conductive test object, initially at a uniform temperature, was exposed to a sudden step change in main flow temperature and a time-resolved surface temperature was measured using an IR camera. By assuming constant values of the heat transfer coefficient and the film cooling effectiveness over time, the heat equation was solved using least squares.The prototype vane was tested for different film cooling row positions on the pressure and suction side. Both cylindrical as well as fan shaped holes were investigated with and without showerhead cooling.The resulting heat transfer coefficient and film cooling effectiveness on the pressure side is compared to flat plate studies and to the results from the suction side. Also, the applicability of using superposition on showerhead cooling and on single/double rows is investigated. Furthermore, the results are compared to other published airfoil film cooling experiments and to CFD analysis for which conclusions are drawn on quantitative and qualitative capabilities of this tool.© 2012 ASME

Implementation of collaborative multidisciplinary design optimization for conceptual design of a complex engineering product

This study investigates the performance of the collaborative multidisciplinary design optimization framework and how it facilitates the knowledge integration process. The framework is used to design and optimize an innovative concept of a tidal water power plant. The case study helps to highlight the challenges that may occur during implementation. The result is presented as a modified framework with less implementation difficulties. The improved framework shows significant reduction in design time and improvement in collaborative design optimization for a design team. The geometry of the product is optimized to minimize weight and maximize the power generated by the turbine with respect to some mechanical constraints.

Multi-variable Correlation for Cylindrical Holes at Suction and Pressure sides of A Turbine Vane

Reliable correlations for predicting film cooling performance is one of the major considerations in the cooling analysis of todays gas turbine engines. In this study correlations have been derived ...

A comprehensive computational multidisciplinary design optimization approach for a tidal power plant turbine

Multidisciplinary design optimization has become a powerful technique to facilitate continuous improvement of complex and multidisciplinary products. Parametric modeling is an essential part with tremendous impact on the flexibility and robustness of multidisciplinary design optimization. This article investigates the effect of relational and non-relational parameterization techniques on the robustness and flexibility of the conceptual design of a multidisciplinary product. Bench marking between relational and non-relational parameterization and their effect on flexibility and robustness indicate that the relational parameterization is an efficient method in the multidisciplinary design optimization process. The inherent properties of the method contribute to an efficient parametric modeling with improved communication between different disciplines. This enhances the performance of the multidisciplinary design optimization process and allows a more flexible and robust design. The considered disciplines are computer-aided design, computational fluid dynamics, finite element analysis, and dynamic simulation. A high-fidelity geometry created in a computer-aided design environment is computer-aided design centric approach and later used in computational fluid dynamics, finite element analysis for a better understanding of the product as it leads to precise outcomes. The proposed approach is implemented for the conceptual design of a novel product, a tidal power plant developed by Minesto AB using a multidisciplinary design optimization process.

Unsteady Effects in the Heat Load Predictions for a Two-Stage Compressor Turbine

Heat load analysis play an important role in the estimation of hot gas components lifetime. To achieve a high level of accuracy in heat load analysis, predicting the temperature distribution on the ...

On the Characteristics of the Jet in Film Cooling Applications

Numerical and experimental investigations are conducted to study the jet characteristics on the pressure side of a film-cooled turbine guide vane. CFD simulations, including both the steady RANS turbulence model, \(k-\omega \) shear stress transport (SST), as well as the hybrid approach, Scale-Adaptive Simulation (SAS), are utilized to comprehend the turbulent flow structures and the vortex dynamics associated to the film cooling jet. For this purpose the commercial CFD code FLUENT has been utilized to study flow with injection of coolant through fan-shaped holes for two blowing ratios (0.6 and 1.2). Although, both turbulence models predict the vortical structures and jet dynamics similarly, the findings suggest that by resolving large energy containing vortices, the SAS model can improve the modeling of mixing properties and thereby approximation of the surface temperature.

A Three-Regime Based Method for Correlating Film Cooling Effectiveness for Cylindrical and Shaped Holes

To cope with high temperature of the gas from combustor, cooling is often used in the hot gas components in gas turbines. Film cooling is one of the effective methods used in this application. Both cylindrical and fan-shaped holes are used in film cooling. There have been a number of correlations published for both cylindrical and fan-shaped holes regarding film cooling effectiveness. Unfortunately there are no definitive correlations for either cylindrical or fan-shaped holes. This is due to the nature of the complexity of film cooling where many factors influence its performance, e.g., blowing ratio, density ratio, surface angle, downstream distance, expansion angle, hole length, turbulence level, etc.A test rig using infrared camera was built to test the film cooling performance for a scaled geometry from a real nozzle guide vane. Both cylindrical and fan-shaped holes were tested. To correlate the experimental data, a three-regime based method was developed for predicting the film cooling effectiveness. Based on the blowing ratio, the proposed method divides the film cooling performance in three regimes: fully attached (or no jet lift-off), fully jet lift-off, and the transition regime in between. Two separate correlations are developed for fully attached and full jet lift-off regimes, respectively. The method of interpolation from these two regimes is used to predict the film cooling effectiveness for the transition regime, based on the blowing ratio. It has been found this method can give a good correlation to match the experimental data, for both cylindrical and fan-shaped holes. A comparison with literature was also carried out, and it showed a good agreement.Copyright