Numerical Investigation on Heat Transfer and Oxidation Deposition of Aviation Fuel in a Rotatory U-Channel

2021 ◽  
Vol 143 (2) ◽  
Author(s):  
Zekun Zheng ◽  
Xinyan Pei ◽  
Siqian Yan ◽  
Lingyun Hou
Keyword(s):  
Heat Transfer ◽  
Deposition Rate ◽  
Turbulent Transport ◽  
Hydrocarbon Fuel ◽  
Deposition Process ◽  
Outer Edge ◽  
Aviation Fuel ◽  
Regenerative Cooling ◽  
Turbine Cooling ◽  
Rotation Numbers

Abstract Liquid-fuel regenerative cooling is a promising turbine cooling technology. We developed a numerical model of heat transfer coupled with oxidation deposition in a rotatory channel for regenerative cooling applications. Source terms for the centrifugal and Coriolis forces caused by rotation were added to the momentum equations and turbulent transport equations. A kinetic model for the thermal oxidation and deposition of supercritical hydrocarbon fuel was used to predict the oxidation deposition process. Coupled fluid–solid simulations of the heat transfer and oxidation deposition of hydrocarbon fuel in a U-shaped channel at five rotation numbers showed that the rotation improves convective heat transfer in the cooling channel and prevents the occurrence of a heat transfer deterioration zone. The average deposition rate in the channel decreased with increasing rotation number. In the centrifugal section of the rotatory channel, the Coriolis force caused the temperatures of the leading wall to be higher than those of the trailing wall, but the differences became smaller and nearly disappeared in the elbow and centripetal sections. The deposition rate on the leading wall was higher than that on the trailing wall in the straight centrifugal channel. In the bending section, the oxidation deposits were more prone to form on the inner edge than on the outer edge.

Flow and Heat Transfer Characteristics of Supercritical Hydrocarbon Fuel in Mini Channels With Dimples

2017 ◽  
Vol 139 (12) ◽  
Author(s):  
Yu Feng ◽  
Jie Cao ◽  
Xin Li ◽  
Silong Zhang ◽  
Jiang Qin ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Hydrocarbon Fuel ◽  
Fuel Properties ◽  
Heated Wall ◽  
Cooling Channel ◽  
Heat Transfer Characteristics ◽  
Regenerative Cooling ◽  
Transfer Characteristics ◽  
Flow And Heat Transfer ◽  
Cooling Passage

An idea of using dimples as heat transfer enhancement device in a regenerative cooling passage is proposed to extend the cooling limits for liquid-propellant rocket and scramjet. Numerical studies have been conducted to investigate the flow and heat transfer characteristics of supercritical hydrocarbon fuel in a rectangular cooling channel with dimples applied to the bottom wall. The numerical model is validated through experimental data and accounts for real fuel properties at supercritical pressures. The study shows that the dimples can significantly enhance the convective heat transfer and reduce the heated wall temperature. The average heat transfer rate of the dimpled channel is 1.64 times higher than that of its smooth counterpart while the pressure drop in the dimpled channel is only 1.33 times higher than that of the smooth channel. Furthermore, the thermal stratification in a regenerative cooling channel is alleviated by using dimples. Although heat transfer deterioration of supercritical fluid flow in the trans-critical region cannot be eliminated in the dimpled channel, it can be postponed and greatly weakened. The strong variations of fuel properties are responsible for the local acceleration of fuel and variation of heat transfer performance along the cooling channel.

Heat Transfer Measurements in Rotating Blade–Shape Serpentine Coolant Passage With Ribbed Walls at High Reynolds Numbers

2014 ◽  
Vol 136 (9) ◽  
Author(s):  
Akhilesh Rallabandi ◽  
Jiang Lei ◽  
Je-Chin Han ◽  
Salam Azad ◽  
Ching-Pang Lee
Keyword(s):  
Heat Transfer ◽  
Reynolds Numbers ◽  
Copper Plate ◽  
Working Fluid ◽  
Transfer Coefficients ◽  
Significant Deterioration ◽  
Turbine Cooling ◽  
Experimental Heat ◽  
Rotation Numbers ◽  
High Reynolds

Flow in the internal three-pass serpentine rib turbulated passages of an advanced high pressure rotor blade is simulated on a 1:1 scale in the laboratory. Tests to measure the effect of rotation on the Nusselt number are conducted at rotation numbers up to 0.4 and Reynolds numbers from 75,000 to 165,000. To achieve this similitude, pressurized Freon R134a vapor is utilized as the working fluid. Experimental heat transfer coefficient measurements are made using the copper-plate regional average method. Regional heat transfer coefficients are correlated with rotation numbers. An increase in heat transfer rates due to rotation is observed in radially outward passes; a reduction in heat transfer rate is observed in the radially inward pass. Strikingly, a significant deterioration in heat transfer is noticed in the “hub” region—between the radially inward second pass and the radially outward third pass. This heat transfer reduction is critical for turbine cooling designs.

scholarly journals Effect of Dimple Depth-Diameter Ratio on the Flow and Heat Transfer Characteristics of Supercritical Hydrocarbon Fuel in Regenerative Cooling Channel

2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Lihan Li ◽  
Xin Li ◽  
Jiang Qin ◽  
Silong Zhang ◽  
Wen Bao
Keyword(s):  
Heat Transfer ◽  
Pressure Loss ◽  
Hydrocarbon Fuel ◽  
Diameter Ratio ◽  
Fluid Temperature ◽  
Cooling Channel ◽  
Heat Transfer Characteristics ◽  
Regenerative Cooling ◽  
Transfer Characteristics ◽  
Flow And Heat Transfer

In order to extend the cooling capacity of thermal protection in various advanced propulsion systems, dimple as an effective heat transfer enhancement device with low-pressure loss has been proposed in regenerative cooling channels of a scramjet. In this paper, numerical simulation is conducted to investigate the effect of the dimple depth-diameter ratio on the flow and heat transfer characteristics of supercritical hydrocarbon fuel inside the cooling channel. The thermal performance factor is adopted to evaluate the local synthetically heat transfer. The results show that increasing the dimple depth-diameter ratio h / d p can significantly reduce wall temperature and enhance the heat transfer inside the cooling channel but simultaneously increase pressure loss. The reason is that when h / d p is rising, the recirculation zones inside dimples would be enlarged and the reattachment point is moving downstream, which enlarge both the high Nu area at rear edge of dimple and the low Nu area in dimple front. In addition, when fluid temperature is nearer the fluid pseudocritical temperature, local acceleration caused by dramatic fluid property change would reduce the increment of heat transfer and also reduce pressure loss. In this study, the optimal depth-diameter ratio of dimple in regenerative cooling channel of hydrocarbon fueled is 0.2.

Coupling Process Analysis on the Flow and Heat Transfer of Hydrocarbon Fuel With Pyrolysis and Pyrolytic Coking Under Supercritical Pressures

2018 ◽  
Author(s):  
Chaofan Zhao ◽  
Xizhuo Hu ◽  
Jianqin Zhu ◽  
Zhi Tao
Keyword(s):  
Heat Transfer ◽  
High Temperature ◽  
Cooling System ◽  
Process Analysis ◽  
Hydrocarbon Fuel ◽  
Strong Impact ◽  
Regenerative Cooling ◽  
Flow And Heat Transfer ◽  
Cooling Tube ◽  
Scramjet Engine

The regenerative cooling technology has become the most effective method to reduce the high-temperature of the scramjet engine. With physical and chemical heat sink, the endothermic hydrocarbon fuel has excellent performance in the regenerative cooling system of the scramjet engine which operates under extremely high temperature. The pyrolytic reactions not only absorb a large amount of heat, but also produce some kinds of coking precursors, mainly alkenes and aromatics. Because of the coking precursors and the coking reactions, a lot of coke would be generated on the wall and exert strong impact on the heat transfer, as the conductivity of the coke is much lower than that of the metal wall. Meanwhile, the surface coking changes the geometric parameters of the cooling tube, which leads to the flow field variations with the thickening coking layer. So, it is needed to find out the interaction between these variations. In this paper, a one-dimensional (1D) model has been developed to calculate the flow and heat transfer parameters distributions of the pyrolytically reacted RP-3 along the regenerative cooling tube with the pyrolytic coking. The 24-step pyrolytic reaction model and the coking kinetic model are applied to predict the pyrolysis and pyrolytic coking process of RP-3, with accurate computations of the physical properties of fluid mixture which undergo drastic variations during the transcritical process. Comparisons between the current predictions and the open published experimental data are carried out and good agreement is achieved. Calculations on the coupling relationships between the flow, heat transfer, pyrolysis and pyrolytic coking within 20 min in the circular tube have been conducted. With the heat flux increased, the coke mass is rising sharply and the temperature of the outer tube wall rises rapidly owing to the increasing thermal resistance of the coke layer. Moreover, the flow velocity becomes faster during the narrowing process of the tube caused by surface coking. In order to better understand the coking characteristics, further investigations on distributions of the surface coking under heat fluxes of 1.2–2.0MW/m2, pressures of 2.6–7.4 MPa and with inlet velocities of 0–5m/s have been performed. Results reveal that all these factors play an important role in the pyrolytic reactions and the coking rate distributions. The results in this paper have significant reference value in the design of the regenerative cooling system.

Heat Transfer Measurements in Rotating Blade-Shape Serpentine Coolant Passage With Ribbed Walls at High Reynolds Numbers

2013 ◽  
Author(s):  
Akhilesh Rallabandi ◽  
Jiang Lei ◽  
Je-Chin Han ◽  
Salam Azad ◽  
Ching-Pang Lee
Keyword(s):  
Heat Transfer ◽  
Reynolds Numbers ◽  
Working Fluid ◽  
Transfer Coefficients ◽  
Significant Deterioration ◽  
Turbine Cooling ◽  
Heat Transfer Coefficients ◽  
Experimental Heat ◽  
Rotation Numbers ◽  
High Reynolds

Flow in the internal three-pass serpentine rib turbulated passages of an advanced high pressure rotor blade is simulated on a 1:1 scale in the laboratory. Tests to measure the effect of rotation on the Nusselt number are conducted at rotation numbers up to 0.4 and Reynolds numbers from 75,000 to 165,000. To achieve this similitude, pressurized Freon R134a vapor is utilized as the working fluid. Experimental heat transfer coefficient measurements are made using the copperplate regional average method. Regional heat transfer coefficients are correlated with rotation numbers. An increase in heat transfer rates due to rotation is observed in radially outward passes; a reduction in heat transfer rate is observed in the radially inward pass. Strikingly, a significant deterioration in heat transfer is noticed in the “hub” region — between the radially inward second pass and the radially outward third pass. This heat transfer reduction is critical for turbine cooling designs.

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