Investigation of Hot Film Jet Vortex Effects on Droplets Characteristics Over Aero-Engine Inlet Strut

2016 ◽  
Author(s):  
Yun Zhang ◽  
Peng Ke ◽  
Chunxin Yang ◽  
Guangfeng Yu
Keyword(s):  
Collection Efficiency ◽  
Droplet Diameter ◽  
Rear Surface ◽  
Leading Edge ◽  
Computation Method ◽  
Blowing Ratio ◽  
Impingement Heat Transfer ◽  
Aero Engine ◽  
Hot Film ◽  
Air Film

The jetted hot film could affect the trajectories of the water droplets near the aero-engine inlet strut surface, which equipped with the ice protection system combined the internal impingement heat transfer and the external hot air film heating. To evaluate the droplets impingement characteristics of four ice-protection structures designed with different film-slot jet angles, a droplets impingement computation method based on Eulerian framework was developed and validated. The influences of film-slot angle and blowing ratio on the impingement characteristics for droplet diameter of 20μm were investigated and the jet vortex was found to be an important factor. The results indicated that the local collection efficiency and the impingement limitation could decrease significantly due to the blowing from the external hot-film, and the influence would be more significant in case that the film-slot was closer to the leading edge. For example, the average local collection efficiencies of four typical configurations with different slot angles and positions decreased 82%, 8%, 1% and 0.5% respectively comparing to those without air film. Besides that, the maximum local collection efficiency and the impingement limitation decreased with the increasing blowing ratios, and the film-slot nearest to the leading edge was most sensitive to the blowing ratio. It was also found that no droplets impinged on the rear surface after the jet slots at some higher blowing ratios.

Analysis of Droplet Impingement Characteristics of Aero-Engine Nose Cone With Hot Air Film

2016 ◽  
Author(s):  
Huiyun Yang ◽  
Peng Ke ◽  
Chunxin Yang
Keyword(s):  
Droplet Diameter ◽  
Simulation Methods ◽  
Droplet Impingement ◽  
Blowing Ratio ◽  
Hot Air ◽  
Impingement Heat Transfer ◽  
Aero Engine ◽  
Nose Cone ◽  
Numerical Simulation Methods ◽  
Air Film

A new nose cone ice protection configuration with hot air film slot was investigated, where the surface need to be protected could be heated with interior impingement heat transfer and exterior hot air film. Numerical simulation methods using computational fluid dynamics code were developed and validated to find the effects of the jetted air film on the droplet impingement characteristics. Combination of two-dimensional axisymmetric algorithm and Lagrangian method were adopted to solve the air flow field and the droplet trajectories. The simulation methods were validated with the results from the experimental data. The droplet impingement characteristics on two structures were investigated respectively, the intact cone without film slot and the slotted cone. Results show that the surface local collection coefficient changes significantly behind the film slot because of the blowing effect of the air film on the incoming droplets, and the variation of the local collection coefficient is very dependent on the droplet diameter for a given blowing ratio, or the blowing ratio for a given droplet size. Some different effects, such as “fully blowing-off”, “blowing behind” and “limited blowing-off”, may happen for different combination of droplets size and blowing ratio. Compared with the cone without film slot, the blowing effect is more significant for smaller droplets or higher blowing ratio. Besides that, the total collection coefficient maybe only half of those without film for some conditions.

Numerical Study on Film Effectiveness and Heat Transfer Characteristics of Aero-Engine Nose Cone With Hot Air Film

2020 ◽  
Author(s):  
Tao Yang ◽  
Li Zhang ◽  
Hui-Ren Zhu ◽  
Xing-Ming Wang
Keyword(s):  
Heat Transfer ◽  
Numerical Study ◽  
Windward Side ◽  
Heat Transfer Characteristics ◽  
Hole Shape ◽  
Blowing Ratio ◽  
Transfer Characteristics ◽  
Aero Engine ◽  
Nose Cone ◽  
Hot Film

Abstract When the aircraft works in an environment containing supercooled water droplets, it is easy to cause the engine inlet nose cone on the windward side to freeze, which not only affects the performance of the engine, but also leads to flight accidents. Therefore, it is necessary to research the anti-icing technology of aero-engine nose cone components. At present, the air intake cone of the aircraft mainly forms a thermal anti-icing system by means of hot film anti-icing and heating impingement anti-icing. In this paper, the effects of blowing ratio, film hole pitch, hole shape and film hole arrangement method on film heating effectiveness and heat transfer characteristics are studied by numerical simulation methods for the hot film anti-icing system of the nose cone. The results show that with the increase of the blowing ratio, the film heating effectiveness in the downstream area quickly decreases first and then increases, and the range of change aggrandizes. Under the given condition, as the pitch between the film holes decreases, the area covered by the film extends, and the heating effectiveness improves significantly. In the case of high blowing ratio, the advantage of film heating effectiveness of waist-shaped film hole is more apparent. The laterally-averaged film heating effectiveness of the staggered film holes is much higher than that of the aligned film holes. For the characteristics of film heat transfer, the hole pitch and hole shape has little effect on the heat transfer characteristics at low blowing ratio. In the case of high blowing ratio, the heat transfer effect will be greatly weakened when the hole pitch is increased, moreover the heat transfer efficiency of the waist-shaped hole is better. In the region near the exit of the secondary row film hole, the heat transfer characteristics of the staggered structure is stronger than that in the aligned structure. In addition, it is found that the high heat transfer region for staggered arrangement shows W–shaped.

Overall Effectiveness for a Film Cooled Turbine Blade Leading Edge With Varying Hole Pitch

2010 ◽  
Author(s):  
Thomas E. Dyson ◽  
Dave G. Bogard ◽  
Justin D. Piggush ◽  
Atul Kohli
Keyword(s):  
Turbine Blade ◽  
Hot Spots ◽  
Leading Edge ◽  
Stagnation Line ◽  
Convective Cooling ◽  
Impingement Cooling ◽  
Blowing Ratio ◽  
Cylindrical Holes ◽  
Overall Effectiveness ◽  
Blade Leading Edge

Overall effectiveness, φ, for a simulated turbine blade leading edge was experimentally measured using a model constructed with a relatively high conductivity material selected so that the Biot number of the model matched engine conditions. The model incorporated three rows of cylindrical holes with the center row positioned on the stagnation line. Internally the model used an impingement cooling configuration. Overall effectiveness was measured for pitch variation from 7.6d to 9.6d for blowing ratios ranging from 0.5 to 3.0, and angle of attack from −7.7° to +7.7°. Performance was evaluated for operation with a constant overall mass flow rate of coolant. Consequently when increasing the pitch, the blowing ratio was increased proportionally. The increased blowing ratio resulted in increased impingement cooling internally and increased convective cooling through the holes. The increased internal and convective cooling compensated, to a degree, for the decreased coolant coverage with increased pitch. Performance was evaluated in terms of laterally averaged φ, but also in terms of the minimum φ. The minimum φ evaluation revealed localized hot spots which are arguably more critical to turbine blade durability than the laterally averaged results. For small increases in pitch there was negligible decrease in performance.

Unsteady simulations of migration and deposition of fly-ash particles in the first-stage turbine of an aero-engine

2021 ◽  
pp. 1-21
Author(s):  
Z. Hao ◽  
X. Yang ◽  
Z. Feng
Keyword(s):  
Fly Ash ◽  
Film Cooling ◽  
Particle Deposition ◽  
Flow Characteristics ◽  
Leading Edge ◽  
Velocity Model ◽  
Operating Conditions ◽  
Inlet Temperature ◽  
Internal Cooling ◽  
Aero Engine

Abstract Particulate deposits in aero-engine turbines change the profile of blades, increase the blade surface roughness and block internal cooling channels and film cooling holes, which generally leads to the degradation of aerodynamic and cooling performance. To reveal particle deposition effects in the turbine, unsteady simulations were performed by investigating the migration patterns and deposition characteristics of the particle contaminant in a one-stage, high-pressure turbine of an aero-engine. Two typical operating conditions of the aero-engine, i.e. high-temperature take-off and economic cruise, were discussed, and the effects of particle size on the migration and deposition of fly-ash particles were demonstrated. A critical velocity model was applied to predict particle deposition. Comparisons between the stator and rotor were made by presenting the concentration and trajectory of the particles and the resulting deposition patterns on the aerofoil surfaces. Results show that the migration and deposition of the particles in the stator passage is dominated by the flow characteristics of fluid and the property of particles. In the subsequential rotor passage, in addition to these factors, particles are also affected by the stator–rotor interaction and the interference between rotors. With higher inlet temperature and larger diameter of the particle, the quantity of deposits increases and the deposition is distributed mainly on the Pressure Side (PS) and the Leading Edge (LE) of the aerofoil.

Effects of alternating elliptical chamber on jet impingement heat transfer in vane leading edge under different cross-flow conditions

2021 ◽  
pp. 1-17
Author(s):  
K. Xiao ◽  
J. He ◽  
Z. Feng
Keyword(s):  
Heat Transfer ◽  
Velocity Ratio ◽  
Cross Flow ◽  
Leading Edge ◽  
Longitudinal Vortices ◽  
Impingement Jet ◽  
Flow And Heat Transfer ◽  
Impingement Heat Transfer ◽  
Cross Flow Velocity ◽  
The Cross

ABSTRACT This paper proposes an alternating elliptical impingement chamber in the leading edge of a gas turbine to restrain the cross flow and enhance the heat transfer, and investigates the detailed flow and heat transfer characteristics. The chamber consists of straight sections and transition sections. Numerical simulations are performed by solving the three-dimensional (3D) steady Reynolds-Averaged Navier–Stokes (RANS) equations with the Shear Stress Transport (SST) k– $\omega$ turbulence model. The influences of alternating the cross section on the impingement flow and heat transfer of the chamber are studied by comparison with a smooth semi-elliptical impingement chamber at a cross-flow Velocity Ratio (VR) of 0.2 and Temperature Ratio (TR) of 1.00 in the primary study. Then, the effects of the cross-flow VR and TR are further investigated. The results reveal that, in the semi-elliptical impingement chamber, the impingement jet is deflected by the cross flow and the heat transfer performance is degraded. However, in the alternating elliptical chamber, the cross flow is transformed to a pair of longitudinal vortices, and the flow direction at the centre of the cross section is parallel to the impingement jet, thus improving the jet penetration ability and enhancing the impingement heat transfer. In addition, the heat transfer in the semi-elliptical chamber degrades rapidly away from the stagnation region, while the longitudinal vortices enhance the heat transfer further, making the heat transfer coefficient distribution more uniform. The Nusselt number decreases with increase of VR and TR for both the semi-elliptical chamber and the alternating elliptical chamber. The alternating elliptical chamber enhances the heat transfer and moves the stagnation point up for all VR and TR, and the heat transfer enhancement is more obvious at high cross-flow velocity ratio.

Effect of Periodic Wake Passing on Film Effectiveness of Discrete Cooling Holes Around the Leading Edge of a Blunt Body

1997 ◽  
Vol 119 (2) ◽  
pp. 292-301 ◽  
Author(s):  
K. Funazaki ◽  
M. Yokota ◽  
S. Yamawaki
Keyword(s):  
Blunt Body ◽  
Free Stream ◽  
Turbine Blades ◽  
Density Ratio ◽  
Leading Edge ◽  
Test Model ◽  
Free Stream Turbulence ◽  
Aero Engine ◽  
Secondary Air ◽  
Wake Passing

Detailed studies are conducted on film effectiveness of discrete cooling holes around the leading edge of a blunt body that is subjected to periodically incoming wakes as well as free-stream turbulence with various levels of intensity. The cooling holes have a configuration similar to that of typical turbine blades except for the spanwise inclination angle. Secondary air is heated so that the temperature difference between the mainstream and secondary air is about 20 K. In this case, the air density ratio of the mainstream and secondary air becomes less than unity, therefore the flow condition encountered in an actual aero-engine cannot be simulated in terms of the density ratio. A spoke-wheel type wake generator is used in this study. In addition, three types of turbulence grids are used to elevate the free-stream turbulence intensity. We adopt three blowing ratios of the secondary air to the mainstream. For each of the blowing ratios, wall temperatures around the surface of the test model are measured by thermocouples situated inside the model. The temperature is visualized using liquid crystals in order to obtain qualitative information of film effectiveness distribution.

The Effect of Periodic Wake Passing on Film Effectiveness of Discrete Cooling Holes Around the Leading Edge of a Blunt Body

1995 ◽  
Author(s):  
K. Funazaki ◽  
M. Yokota ◽  
S. Yamawaki
Keyword(s):  
Blunt Body ◽  
Free Stream ◽  
Turbine Blades ◽  
Density Ratio ◽  
Leading Edge ◽  
Test Model ◽  
Free Stream Turbulence ◽  
Aero Engine ◽  
Secondary Air ◽  
Wake Passing

Detailed studies are conducted on film effectiveness of discrete cooling holes around the leading edge of a blunt body that is subjected to periodically incoming wakes as well as free-stream turbulence with various levels of intensity. The cooling holes have a configuration similar to that of typical turbine blades except for the spanwise inclination angle. Secondary air is heated so that the temperature difference between the mainstream and secondary air is about 20K. In this case, air density ratio of the mainstream and secondary air becomes less than unity, therefore the flow condition encountered in an actual aero-engine can not be simulated in terms of the density ratio. A spoke-wheel type wake generator is used in this study. In addition, three types of turbulence grids are used to elevate the free-stream turbulence intensity. We adopt three blowing ratios of the secondary air to the mainstream. For each of the blowing ratios, wall temperature around the surface of the test model are measured by thermocouples situated inside the model. The temperature is visualized using liquid crystals in order to obtain qualitative information of film effectiveness distribution.

Numerical Simulation of Impinging Cooling on the Leading Edge of a Turbine Blade

2011 ◽  
Author(s):  
Keyong Cheng ◽  
Xiulan Huai ◽  
Jun Cai ◽  
Zhixiong Guo
Keyword(s):  
Numerical Simulation ◽  
Turbine Blade ◽  
Leading Edge ◽  
Critical Factor ◽  
Main Stream ◽  
Experimental Conditions ◽  
Cooling Effectiveness ◽  
Blowing Ratio ◽  
Lower Temperature ◽  
Simulation Parameters

In the present study, numerical simulation is carried out for impingement/effusion cooling on the leading edge of a turbine blade similar to an experimental model tested previously. The k-ε turbulence model is used, and simulation parameters are set in accordance with the experimental conditions, including temperature ratio, blowing ratio, and Reynolds number of the main stream. The accuracy and reliability of the simulation is verified by the experimental data, and the influence of various factors on fluid flow and heat transfer is analyzed in detail. The results indicate that the blowing ratio is one critical factor which affects the cooling effectiveness. The greater the blowing ratio is, the higher the cooling effectiveness is. In addition, a staggered-holes arrangement is numerically studied and compared with a line-holes arrangement. The results show that the staggered-holes arrangement has a lower temperature on the outer surface of the leading edge and has improved the cooling effectiveness.

Influence of Turbine Blade Leading Edge Profile on Film Cooling With Shaped Holes

2017 ◽  
Author(s):  
Mingjie Zhang ◽  
Nian Wang ◽  
Andrew F. Chen ◽  
Je-Chin Han
Keyword(s):  
Turbine Blade ◽  
Film Cooling ◽  
Density Ratio ◽  
Leading Edge ◽  
Stagnation Line ◽  
Film Cooling Effectiveness ◽  
Blowing Ratio ◽  
Edge Profile ◽  
Elliptical Cylinders ◽  
Blade Leading Edge

This paper presents the turbine blade leading edge model film cooling effectiveness with shaped holes, using the pressure sensitive paint (PSP) mass transfer analogy method. The effects of leading edge profile, coolant to mainstream density ratio and blowing ratio are studied. Computational simulations are performed using the realizable k-ε turbulence model. Effectiveness obtained by CFD simulations are compared with experiments. Three leading edge profiles, including one semi-cylinder and two semi-elliptical cylinders with an after body, are investigated. The ratios of major to minor axis of two semi-elliptical cylinders are 1.5 and 2.0, respectively. The leading edge has three rows of shaped holes. For the semi-cylinder model, shaped holes are located at 0 degrees (stagnation line) and ± 30 degrees. Row spacing between cooling holes and the distance between impingement plate and stagnation line are the same for three leading edge models. The coolant to mainstream density ratio varies from 1.0 to 1.5 and 2.0, and the blowing ratio varies from 0.5 to 1.0 and 1.5. Mainstream Reynolds number is about 100,900 based on the diameter of the leading edge cylinder, and the mainstream turbulence intensity is about 7%. The results provide an understanding of the effects of leading edge profile and on turbine blade leading edge region film cooling with shaped-hole designs.

Flow Field and Hot Streak Migration Through a High Pressure Cooled Vanes With Representative Lean Burn Combustor Outflow

2018 ◽  
Vol 141 (4) ◽  
Author(s):  
Tommaso Bacci ◽  
Tommaso Lenzi ◽  
Alessio Picchi ◽  
Lorenzo Mazzei ◽  
Bruno Facchini
Keyword(s):  
Experimental Data ◽  
High Pressure ◽  
Flow Field ◽  
Fuel Injection ◽  
Leading Edge ◽  
Flame Stabilization ◽  
Lean Burn ◽  
Aero Engine ◽  
University Of Florence ◽  
Hot Streak

Modern lean burn aero-engine combustors make use of relevant swirl degrees for flame stabilization. Moreover, important temperature distortions are generated, in tangential and radial directions, due to discrete fuel injection and liner cooling flows respectively. At the same time, more efficient devices are employed for liner cooling and a less intense mixing with the mainstream occurs. As a result, aggressive swirl fields, high turbulence intensities, and strong hot streaks are achieved at the turbine inlet. In order to understand combustor-turbine flow field interactions, it is mandatory to collect reliable experimental data at representative flow conditions. While the separated effects of temperature, swirl, and turbulence on the first turbine stage have been widely investigated, reduced experimental data is available when it comes to consider all these factors together.In this perspective, an annular three-sector combustor simulator with fully cooled high pressure vanes has been designed and installed at the THT Lab of University of Florence. The test rig is equipped with three axial swirlers, effusion cooled liners, and six film cooled high pressure vanes passages, for a vortex-to-vane count ratio of 1:2. The relative clocking position between swirlers and vanes has been chosen in order to have the leading edge of the central NGV aligned with the central swirler. In order to generate representative conditions, a heated mainstream passes though the axial swirlers of the combustor simulator, while the effusion cooled liners are fed by air at ambient temperature. The resulting flow field exiting from the combustor simulator and approaching the cooled vane can be considered representative of a modern Lean Burn aero engine combustor with swirl angles above ±50 deg, turbulence intensities up to about 28% and maximum-to-minimum temperature ratio of about 1.25. With the final aim of investigating the hot streaks evolution through the cooled high pressure vane, the mean aerothermal field (temperature, pressure, and velocity fields) has been evaluated by means of a five-hole probe equipped with a thermocouple and traversed upstream and downstream of the NGV cascade.

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