scholarly journals Coupled Analysis of the Film-Cooling and Infrared Characteristics of an Axisymmetric Vectored Nozzle

2015 ◽  
Vol 2015 ◽  
pp. 1-8
Author(s):  
Xiaoying Zhang ◽  
Rui Li
Keyword(s):  
Wall Temperature ◽  
Film Cooling ◽  
Heat Shield ◽  
Solution Temperature ◽  
Coupled Analysis ◽  
Band Model ◽  
Infrared Band ◽  
Cooling Effectiveness ◽  
Narrow Band Model ◽  
Experimental Nozzle

This study adopts a narrow band model to investigate the cooling and radiation of a vectoring nozzle and to compute the gas spectral characteristic in infrared band. The radiative heat transfer between the hot gas and the wall is considered with an enclosure model. The calculation of film cooling is performed through a cooling effectiveness method. A coupled heat balance equation of heat flux and wall temperature is established on the multilayer structure of the nozzle, including the wall, heat shield, and outer shield, and a Newton-Raphson scheme is taken for solution. Temperature on the expansion part of an experimental nozzle in NASA TN D-1988 is investigated for verification. Another vectoring nozzle with a multirow of film cooling is also investigated. This study shows that the film in the heat shield remarkably cools the convergent part of the nozzle, thereby increasing the temperature on the expansion part of the nozzle. The deflection of the nozzle can change the distribution of the wall temperature and the radiation on the expansion part, which is lower on the deflection side than on the opposite side. The radiation from the nozzle outlet is high, particularly along the deflection direction in the rear hemisphere.

Film Cooling Effectiveness for Injection from Multirow Holes

1979 ◽  
Vol 101 (1) ◽  
pp. 101-108 ◽  
Author(s):  
M. Sasaki ◽  
K. Takahara ◽  
T. Kumagai ◽  
M. Hamano
Keyword(s):  
Pressure Gradient ◽  
Wall Temperature ◽  
Film Cooling ◽  
Infrared Camera ◽  
Superposition Model ◽  
Adiabatic Wall ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Single Row ◽  
Temperature Distributions

Experimental results are presented for film cooling effectiveness with injection from both a single row and multiple rows of holes with spanwise hole-to-hole spacings of three hole diameters. In the multi-row cases, the injection holes were arranged in staggered patterns with streamwise row-to-row spacings of five or ten hole diameters. Adiabatic wall temperature distributions near and downstream of injection holes were well visualized using a scanning infrared camera. The effect of mainstream pressure gradient was partially included. The additive nature of multi-row film cooling was demonstrated experimentally, in agreement with the Sellers superposition model.

Adiabatic Wall Temperature and Heat Transfer Downstream of Injection Through Two Rows of Holes

1978 ◽  
Vol 100 (2) ◽  
pp. 303-307 ◽  
Author(s):  
M. Y. Jabbari ◽  
R. J. Goldstein
Keyword(s):  
Heat Transfer ◽  
Experimental Investigation ◽  
Heat Transfer Coefficient ◽  
Wall Temperature ◽  
Film Cooling ◽  
Adiabatic Wall ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Single Row ◽  
The Heat Transfer Coefficient

Results of an experimental investigation of film cooling and heat transfer following injection through two staggered rows of holes are reported. The two staggered rows are considerably more effective in protecting the wall than a single row. The film cooling effectiveness at locations beyond about 30-hole dia downstream of injection is laterally uniform. The heat transfer coefficient is within a few percent of that without injection at low blowing rates, but it increases rapidly as the blowing rate increases above unity.

Experimental and Predicted Recovery Temperature Distributions in a Rocket Nozzle With Gaseous Film Cooling

1977 ◽  
Vol 99 (3) ◽  
pp. 386-391 ◽  
Author(s):  
J. J. Williams ◽  
W. H. Giedt
Keyword(s):  
Wall Temperature ◽  
Film Cooling ◽  
Initial Temperature ◽  
Primary Source ◽  
Adiabatic Wall ◽  
Cooling Effectiveness ◽  
Hot Gas ◽  
Temperature Distributions ◽  
Constant Area ◽  
Recovery Temperature

The adiabatic wall temperature distribution in nozzles with gas injection through a peripheral slot at the entrance was investigated. Experimental wall temperature distributions were measured in a series of hot gas (hydrogen-air combustion as the primary source) tests with three geometrically different channels—a constant area duct, a gradually converging nozzle, and a rapidly converging nozzle. Cooling effectiveness was found to be significantly higher for the rapidly converging geometry. Prediction of recovery temperature distributions under the test conditions with available boundary layer computer programs was then investigated. Predicted results were consistently higher than measured. Significantly improved agreement between predicted and measured results was achieved by introducing effective initial temperature profiles in the injectant to account for gross mixing between the injectant gas (nitrogen) and free stream gas at the injection station.

Modal analysis of trailing edge cutback film cooling

2019 ◽  
Vol 30 (8) ◽  
pp. 3957-3983
Author(s):  
Yuxi Luo ◽  
Fengbo Wen ◽  
Rui Hou ◽  
Shuai Wang ◽  
Songtao Wang ◽  
...  
Keyword(s):  
Modal Analysis ◽  
Wall Temperature ◽  
Vortex Structure ◽  
Film Cooling ◽  
Streamwise Vortex ◽  
Analysis Method ◽  
Trailing Edge ◽  
Cooling Effectiveness ◽  
Content Type ◽  
The Relationship

Purpose The purpose of this paper devoted to the application of modal analysis to analyze the flow structure of trailing edge cutback film cooling and the effects of vortex structure on the film cooling effectiveness of the cutback surface. Design/methodology/approach Large eddy simulation (LES) is used to simulate the trailing edge cutback film cooling. The results of LES are analyzed by proper orthogonal decomposition (POD) method and dynamic mode decomposition (DMD) method. The POD method is used to determine the dominated vortex structure and the energy level of these structures. The DMD method is used to analyze the relationship between vortex structures and wall temperature. Findings The POD method shows that the flow field consists of three main vortices – streamwise vortex, lip vortex and coolant vortex. The DMD results show that the lip vortex mainly acts on the middle section of the cutback surface, while the streamwise vortex mainly acts on the back section of the cutback surface. Research limitations/implications The modal analysis is only based on numerical simulation but the modal analysis of experimental results will be further studied in the future. Practical implications This paper presents the powerful ability of the modal analysis method to study complex flows in trailing edge cutback film cooling. Establishing the relationship between vortex and wall temperature by modal analysis method can provide a new idea for studying convective heat transfer problems. Originality/value The role of streamwise vortex in the flow of the trailing edge cutback cooling and its effect on the cooling effectiveness of the cutback surface is found.

IMPROVING ADIABATIC FILM-COOLING EFFECTIVENESS BY USING AN UPSTREAM PYRAMID

2016 ◽  
Vol 8 (2) ◽  
pp. 135-146 ◽  
Author(s):  
Zineb Hammami ◽  
Zineddine Ahmed Dellil ◽  
Fadela Nemdili ◽  
Abbes Azzi
Keyword(s):  
Film Cooling ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness

The Effect of Using Ramps with Trench Cylindrical Holes on Film Cooling Effectiveness

2015 ◽  
Vol 3 (2) ◽  
pp. 15-27
Author(s):  
Ahmed A. Imram ◽  
Humam K. Jalghef ◽  
Falah F. Hatem
Keyword(s):  
Numerical Simulation ◽  
Film Cooling ◽  
Air Injection ◽  
Baseline Model ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Blowing Ratio ◽  
Hot Air ◽  
Test Study ◽  
Cylindrical Holes

     The effect of introducing ramp with a cylindrical slot hole on the film cooling effectiveness has been investigated experimentally and numerically. The film cooling effectiveness measurements are obtained experimentally. A test study was performed at a single mainstream with Reynolds number 76600 at three different coolant to mainstream blowing ratios 1.5, 2, and 3. Numerical simulation is introduced to primarily estimate the best ramp configurations and to predict the behavior of the transport phenomena in the region linked closely to the interaction between the coolant air injection and the hot air mainstram flow. The results showed that using ramps with trench cylindrical holes would enhanced the overall film cooling effectiveness by 83.33% compared with baseline model at blowing ratio of 1.5, also  the best overall flim cooling effectevness was obtained at blowing ratio of 2 while it is reduced at blowing ratio of 3.

Conjugate Heat Transfer and Film Cooling of a Multi-Stage Cooling Scheme

2008 ◽  
Author(s):  
M. Ghorab ◽  
S. I. Kim ◽  
I. Hassan
Keyword(s):  
Heat Transfer ◽  
Film Cooling ◽  
Gas Turbines ◽  
Conjugate Heat Transfer ◽  
Density Ratio ◽  
Design Parameters ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Multi Stage ◽  
Internal Gap

Cooling techniques play a key role in improving efficiency and power output of modern gas turbines. The conjugate technique of film and impingement cooling schemes is considered in this study. The Multi-Stage Cooling Scheme (MSCS) involves coolant passing from inside to outside turbine blade through two stages. The first stage; the coolant passes through first hole to internal gap where the impinging jet cools the external layer of the blade. Finally, the coolant passes through the internal gap to the second hole which has specific designed geometry for external film cooling. The effect of design parameters, such as, offset distance between two-stage holes, gap height, and inclination angle of the first hole, on upstream conjugate heat transfer rate and downstream film cooling effectiveness performance are investigated computationally. An Inconel 617 alloy with variable properties is selected for the solid material. The conjugate heat transfer and film cooling characteristics of MSCS are analyzed across blowing ratios of Br = 1 and 2 for density ratio, 2. This study presents upstream wall temperature distributions due to conjugate heat transfer for different gap design parameters. The maximum film cooling effectiveness with upstream conjugate heat transfer is less than adiabatic film cooling effectiveness by 24–34%. However, the full coverage of cooling effectiveness in spanwise direction can be obtained using internal cooling with conjugate heat transfer, whereas adiabatic film cooling effectiveness has narrow distribution.

scholarly journals Investigations on the effect of different influencing factors on film cooling effectiveness under the injection of synthetic coolant

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Jianlong Chang ◽  
Xinlei Duan ◽  
Yang Du ◽  
Baoquan Guo ◽  
Yutian Pan
Keyword(s):  
Film Cooling ◽  
Elliptical Hole ◽  
Synthetic Jet ◽  
Cooling Effect ◽  
Flow Structures ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Cooling Flow ◽  
Cooling Method ◽  
Strong Controllability

AbstractBy combining the synthetic jet and film cooling, the incident cooling flow is specially treated to find a better film cooling method. Numerical simulations of the synthetic coolant ejected are carried out for analyzing the cooling performance in detail, under different blowing ratios, hole patterns, Strouhal numbers, and various orders of incidence for the two rows of holes. By comparing the flow structures and the cooling effect corresponding to the synthetic coolant and the steady coolant fields, it is found that within the scope of the investigations, the best cooling effect can be obtained under the incident conditions of an elliptical hole with the aspect ratio of 0.618, the blow molding ratio of 2.5, and the Strouhal number St = 0.22. Due to the strong controllability of the synthetic coolant, the synthetic coolant can be controlled through adjusting the frequency of blowing and suction, so as to change the interaction between vortex structures for improving film cooling effect in turn. As a result, the synthetic coolant ejection is more advisable in certain conditions to achieve better outcomes.

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