Abstract: In this study, the local jet velocity distribution for a combined impingement and film cooled high-pressure nozzle guide vane system was analyzed, using flow visualization and PIV-assisted measurement. The measurements including flow visualization were performed on the stagnation row of an NGV to understand its complex flow pattern. PIV technique was used to measure the effused coolant jet exit velocity field in two-dimensional vertical planes. The computations were performed by ANSYS FLUENT 14.5 SOLVER using shear stress transport (SST) k-ω turbulence model. Three laboratory test cases that correspond to inlet coolant mass flow rates of 0.0032, 0.0045 and 0.0054 kg/s, at the region of an FIT, were studied. The numerical results for the spanwise coolant velocity at stagnation row of the film holes agreed well with the PIV experimental data on the same vane configuration. © 2017, The Visualization Society of Japan.

B. V.S.S.S. Prasad

Department of Mechanical Engineering

IIT Madras is a public technical and research university located in Chennai, Tamil Nadu. Founded in 1959, it is recognised as an Institute of National Importance.

IIT Madras has been ranked as the top engineering institute in India for four years in a row by the National Institutional Ranking Framework of the MHRD

It currently offers undergraduate, postgraduate and research degrees across 16 disciplines in Engineering, Sciences, Humanities and Management. About 596 faculty belonging to science and engineering departments and centres of the Institute are engaged in teaching, research and industrial consultancy.

IIT Madras

Journal of Visualization

The present paper describes a system-level thermo-fluid network analysis for the secondary air system analysis of a typically film-cooled nozzle guide vane with multiple actions of jet impingement. The one-dimensional simulation was done with the help of the commercially available Flownex 2015 software. The system-level thermo-fluid network results were validated with both the computational fluid dynamics results and experimentally available literature. The entire nozzle guide vane geometry was first mapped to a thermo-fluid network model and the pressure conditions at different nodes. The discharge and heat transfer coefficients obtained from the Ansys FLUENT were specified as inputs to the thermo-fluid network model. The results show that the one-dimensional simulation of the coolant mass flow rates and jet Nusselt number values are in good agreement with the three-dimensional computational fluid dynamics results. © IMechE 2018.

Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering

Network analysis of a coolant flow performance for the combined impingement and film cooled first-stage of high pressure gas turbine nozzle guide vane

Multi-objective optimization of the film cooled holes for the coupled impingement-film cooled nozzle guide vane is conducted. Two objectives are considered to be minimized: coolant jet exit total temperature and static pressure drop, to assess the trade-off between them. Three-dimensional computationally using SIMPLE algorithm analysis and a k-? SST turbulence model are used for generating a data base. The plenum mass flow rates and mainstream velocity are considered as the two design variables. The second order polynomial response surface method is chosen to develop the objective function approximation. The multi-objective optimization has been carried out with help of a genetic algorithm and sequential quadratic programing (fminicon) in MATLAB 7.11.0 (R2010b). The Pareto-optimal design points are obtained as the plenum coolant mass flow rate of 0.004kg/s and mainstream velocity of 10m/s. Based on these results, the global minimum coolant jet static pressure drop of 32.5 Pa and global minimum jet exit total temperature of 312K are observed for the film holes of the NGV surface. At these operating conditions, the coupled impingement -film cooled NGV is subjected to its higher safety and durability. This happened due to without cause of hot gas ingestion into the film cooled jets of the typically cooled NGV. Copyright © 2017 ASME.

ASME 2017 Gas Turbine India Conference, GTINDIA 2017

Secondary air performance optimization of a combined impingement and film cooled gas turbine nozzle guide vane

The present numerical investigation of Leading Edge (LE) Nozzle Guide Vane (NGV) is considered with five rows of impingement holes combined with five rows of film cooled for the secondary coolant flow path analysis. The coolant mass flow rate variations in all the LE rows of the film holes externally subjected to the hot main stream were obtained by making a three-dimensional computational analysis of NGV with a staggered array of film cooled rows. The experiments were carried out for the same NGV using Particle Image Velocimetry technique to determine the effused coolant jet exit velocity at the stagnation row of film holes as mentioned in reference [Kukutla PR, Prasad BVSSS. Secondary flow visualization on stagnation row of a combined impingement and film cooled high pressure gas turbine nozzle guide vane using PIV technique, J Visualization, 2017; DOI: 10.1007/s12650-017-0434-6]. In this paper, results are presented for three different mass flow rates ranges from 0.0037 kg/s to 0.0075 kg/s supplied at the Front Impingement Tube (FIT) plenum. And the mainstream velocity 6 m/s was maintained for all the three coolant mass flow rates. The secondary coolant flow distribution was performed from SH1 to SH5 row of film holes. Each row of a showerhead film hole exit coolant mass flow rate varied in proportion to the amount of coolant mass rates supplied at the FIT cooling channel. The corresponding minimum and maximum values and their film hole locations were altered. The same behaviour was continued for the coolant pressure drop and temperature rise from SH1 to SH5 row of film holes. Owing to the interaction between hot main stream and the coolant that effuses out of the film holes, occasional presence of hot gas ingestion was noticed for certain flow rates. This caused nonlinear distribution in mass flow, pressure drop and temperature rise. The minimum flow rate results estimate oxidation of NGV material near the film cooled hole. And the effect of hot gas ingestion on the ejected film cooled jet which would recommends effective oxidation resistant material which in turn leads to better durability of the NGV surface. © 2017 Walter de Gruyter GmbH, Berlin/Boston.

Fulltext

International Journal of Turbo and Jet Engines

Numerical Study on the Secondary Air Performance of the Film Holes for the Combined Impingement and Film Cooled First Stage of High Pressure Gas Turbine Nozzle Guide Vane

A computational and experimental study is carried out on the leading edge region of a typical gas turbine NGV, cooled by a combination of impingement and showerhead film cooling. A detailed flow and conjugate heat transfer study has revealed the complex flow structure owing to the coolant-mainstream interaction and the influence of vane material thermal conductivity. The local effectiveness values obtained by the computations agreed well with the experimental data from IR thermography. The effect of blowing ratio on the overall effectiveness is found to be strongly dependent on the vane material conductivity. The effect of blowing ratio is also found to be different towards the pressure and suction sides of the stagnation region. However, the overall effectiveness is found to decrease by about 12% and 6% for low and high conducting materials, respectively, with an increase in mainstream Reynolds number from Re = 4.8 × 10 5 to 14.4 × 10 5. © 2015 Dileep Chandran and Bhamidi Prasad.

International Journal of Rotating Machinery

Conjugate heat transfer study of combined impingement and showerhead film cooling near NGV leading edge

Experiments in Fluids

On the correspondence between flow structures and convective heat transfer augmentation for multiple jet impingement

Journal of Turbomachinery

Aerothermal Investigation of a Single Row Divergent Narrow Impingement Channel by Particle Image Velocimetry and Liquid Crystal Thermography

Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy

Heat transfer characteristics of high crossflow impingement channels: Effect of number of holes

Experimental Thermal and Fluid Science

An experimental investigation of secondary flow characteristics in a linear turbine cascade with upstream converging slot-holes using TR-PIV

Secondary flow visualization on stagnation row of a combined impingement and film cooled high-pressure gas turbine nozzle guide vane using PIV technique

Journal	Data powered by TypesetJournal of Visualization
Publisher	Data powered by TypesetSpringer Verlag
ISSN	13438875
Open Access	No