Begell House Inc.
Heat Transfer Research
HTR
1064-2285
51
13
2020
EXPERIMENTAL INVESTIGATION OF THE CHARACTERISTICS OF R290 CONDENSATION HEAT TRANSFER ENHANCEMENT IN A HORIZONTAL MICROFINNED TUBE
1169-1180
10.1615/HeatTransRes.2020031194
Lele
Wang
School of Mechanical and Electrical Engineering, Nanchang University, Nanchang, Jiangxi
Province, 330031, China
Siyao
Tian
School of Mechanical and Electrical Engineering, Nanchang University, Nanchang, Jiangxi
Province, 330031, China
Yuande
Dai
School of Mechatronics Engineering, Nanchang University, Nanchang, Jiangxi Province, 330031,
China
Sikai
Zou
School of Mechanical and Electrical Engineering, Nanchang University, Nanchang, Jiangxi
Province, 330031, China
R290
flow
phase change
condensation heat transfer
microfinned tube
strengthening
The condensation heat transfer characteristics of R290 (propane) in a horizontal smooth copper tube and a microfinned copper tube with an outside diameter of 5 mm were investigated experimentally to study the condensation heat transfer strengthening characteristics. The enhancement factor Sf was introduced to characterize the degree of strengthening condensation heat transfer of R290 in a microfinned copper tube, and the effects of mass flux (180-300 kg-m-2·s-1), saturation temperature (313.15-328.15 K), heat flux (5-10 kW·m-2), and vapor quality (0.9-0.1) on the enhancement factor were analyzed. The results showed that the enhancement factor decreased with increasing mass flux or heat flux, but increased with a rising saturation temperature. Beside, the enhancement factor first increased but then decreased with a decreasing vapor quality accompanied by progressive liquefaction of R290. Finally, it was concluded that specific heat transfer conditions are essential to achieve the optimal heat transfer strengthening effect of R290 in tubes.
COUPLED NUMERICAL ANALYSIS OF VARIABLE CROSS-SECTION COOLING CHANNELS IN LOX/METHANE ROCKET ENGINES
1181-1196
10.1615/HeatTransRes.2020029990
Bing
Sun
School of Astronautics, Beihang University, Beij ing 100083, China; Key Laboratory of Spacecraft Design Optimization and Dynamic Simulation Technologies, Minisitry of Education
Meng
Zhang
School of Astronautics, Beihang University, Beij ing 100083, China; Key Laboratory of Spacecraft Design Optimization and Dynamic Simulation Technologies, Minisitry of Education
Ming
Zhang
School of Astronautics, Beihang University, Beij ing 100083, China; Key Laboratory of Spacecraft Design Optimization and Dynamic Simulation Technologies, Minisitry of Education
Junya
Yuan
School of Astronautics, Beihang University, Beij ing 100083, China
supercritical methane
cooling channel
rocket engine
regenerative cooling
A three-dimensional coupled heat transfer model is applied for numerical studies of turbulent flow and heat transfer of methane in variable cross-section cooling channels of LOX/methane rocket engines at a supercritical pressure. The results indicate that when the coolant flows through an abruptly expanding structure, the fluid flow velocity suddenly drops, and the average temperature of the fluid reaches a peak. This effect will increase with increase of the sudden contraction/expansion area ratio. After the coolant flows through the expansion structure, the vortices counteract the effect of the secondary flow generated by the centrifugal force in the convergent section of the thrust chamber. This will reduce the coolant helicity here, finally resulting in low convection heat transfer. Generally speaking, the contraction structure has a certain improvement of the heat transfer of coolant in the cooling channels. Through sensitivity analysis, the variable cross-section cooling channels whose contraction/expansion area ratio varies between 1.25 and 1.5 have the most engineering application under the cases discussed in this paper.
ANALYTICAL MODEL FOR PREDICTION OF EFFECTIVE THERMAL CONDUCTIVITY OF A THREE-PHASE SYSTEM: NANOPARTICLE AS THE THIRD PHASE
1197-1211
10.1615/HeatTransRes.2020034475
Chidambara Raja
S
Ph.D
L. A.
Kumaraswamidhas
Department of Mining Machinery Engineering, Indian Institute of Technology (Indian School of Mines), Dhanbad-826004, India
M.
Ramu
Department of Mechanical Engineering, Amrita School of Engineering, Amrita Vishwa Vidyapeetham, Amrita University, Coimbatore, Tamil nadu, India
packed beds
Brownian motion
porosity
foam
effective thermal conductivity
liquid phase
interfacial layer
nanoparticle
The thermal design of various engineering applications plays a prominent role in deciding the overall efficiency of the system. Nowadays, nanofluids have attracted the interest of researchers due to their excellent thermophysical properties. There were several researches emphasising the importance of two-phase materials and nanofluids in the effective thermal design, but none have attempted to integrate both for analyzing their combined potential thermal benefits. This research paper is aimed at formulation of the general analytical expression using the unit cell approach for the evaluation of effective thermal conductivity (ETC) of two-phase system which is comprised of solid and liquid with nanoparticles as a third phase dispersed in the liquid phase (so called nanofluids). The expressions are evaluated for different samples (packed beds and foams dispersed in nanofluid) and compared with the experimental results of conventional two-phase system. The combined effects of influencing parameters on two-phase materials with the static and dynamic mechanisms of nanofluids have been studied and validated with the standard models. The present model is better suit for predicting ETC of two-phase system in different combinations with nanofluids.
INCREASING THE MUZZLE VELOCITY OF PROJECTILE IN THE MODEL BALLISTIC INSTALLATION BY USING HIGH-DENSITY PROPELLANTS
1213-1219
10.1615/HeatTransRes.2020034468
Konstantin Sergeevich
Rogaev
Research Institute of Applied Mathematics and Mechanics, National Research Tomsk State University, 36 Lenin Ave., Tomsk, 634050, Russia
A. N.
Ishchenko
National Research Tomsk State University, 36 Lenin Ave., Tomsk, 634050, Russia
V.Z.
Kasimov
National Research Tomsk State University, 36 Lenin Ave., Tomsk, 634050, Russia
V. V.
Burkin
National Research Tomsk State University, 36 Lenin Ave., Tomsk, 634050, Russia
A.S.
Dyachkovsky
National Research Tomsk State University, 36 Lenin Ave., Tomsk, 634050, Russia
A.D.
Sidorov
National Research Tomsk State University, 36 Lenin Ave., Tomsk, 634050, Russia
E.Yu.
Stepanov
National Research Tomsk State University, 36 Lenin Ave., Tomsk, 634050, Russia
propellants combustion
high-density propellants
barrel systems
gas dynamics
internal ballistics
traveling charge
In accordance with the early works of the authors, the modernization of the propellant charge is possible by using propellant like a traveling charge pushing a projectile in the barrel. The advantages of this technology are increase in the loading density and propellant mass, and therefore increase in the energy of the propellant. The use of this technology leads to the redistribution of the combustion products' energy in the space behind the projectile. In this work, the problem was solved by increasing the throwing velocity while maintaining the maximum pressure on the bore bott om by using high-density propellants in the form of traveling charge at the conditions of the shot for the model ballistic installation. A comparison of the ballistic parameters for the classical shot scheme and scheme with high-density propellants as traveling charge was made.
TURBULENT FORCED CONVECTION NANOFLUID FLOW OVER AN INCLINED FORWARD-FACING STEP
1221-1240
10.1615/HeatTransRes.2020034082
Rouhollah
Moosavi
Florida International University; Mechanical Engineering Department, Yasouj University, Yasouj, Iran
Ehsan
Jalil
Mechanical Engineering Department, Yasouj University, Yasouj, Iran
Cheng-Xian
Lin
Department of Mechanical and Materials Engineering, Florida International University, 10555 W Flagler Street, Miami, Florida 33174, USA
nanofluids
turbulent forced convection
inclined forward-facing step
CFD
heat transfer
In this investigation, turbulent forced convection nanofluid flow with water as base fluid, Al and Cu as nanoparticles over
an inclined forward-facing step is numerically studied in detail. CFD simulations were performed for a heated forward-facing step channel with different step lengths, and different inclination angles of the step and flow Reynolds number with
ranges of 20° ≤ θ ≤ 80° and 30,000 ≤ Re ≤ 100,000, respectively. The concentrations of Al2O3 and CuO nanoparticles were
varied from 1% to 4% with a particle diameter of 50 nm. For the CFD simulation of the turbulent two-phase nanofluid,
the continuity, momentum, and energy equations were solved by a mixture method using the standard k−ε turbulence
model. The effects of nanoparticle volume fraction, step length, and inclination angle at different Reynolds numbers on heat transfer were compared with that of the base fluid (water). The heat transfer rate improves with the increment of nanoparticle volume fraction, step length, inclination angle, and Reynolds number. Numerical outcomes revealed that Al2O3/water nanofluid has a higher influence of heat transfer compared with CuO/water nanofluid. The highest heat transfer enhancement was almost 26% and 19% for Al2O3/water and CuO/water nanofluids in comparison with the base fluid, respectively.
A correlational equation has been suggested to forecast the mean Nusselt number as functions of various parameters of the
inclined forward-facing step.
EFFECTS OF IMPINGEMENT PARAMETERS ON IMPINGING-FILM COOLING PERFORMANCE
1241-1260
10.1615/HeatTransRes.2020034177
Jingyu
Zhang
College of Energy and Power Engineering, Nanjing University of Aeronautics and Astronautics,
Nanjing, Jiangsu 210016, China;
Jiangsu Province Key Laboratory of Aerospace Power System, Nanjing, Jiangsu 210016, China
Jieli
Wei
NUAA
Xiaomin
He
College of Energy and Power Engineering, Nanjing University of Aeronautics and Astronautics,
Nanjing, Jiangsu 210016, China; Jiangsu Province Key Laboratory of Aerospace Power System, Nanjing, Jiangsu 210016, China
Ji
Li
College of Energy and Power Engineering, Nanjing University of Aeronautics and Astronautics,
Nanjing, Jiangsu 210016, China
Dong
Luo
College of Energy and Power Engineering, Nanjing University of Aeronautics and Astronautics,
Nanjing, Jiangsu 210016, China
Yu
Wu
College of Energy and Power Engineering, Nanjing University of Aeronautics and Astronautics,
Nanjing, Jiangsu 210016, China
impinging-film cooling
cooling effectiveness
liner
film cooling
impingement
jet
combustor
gas turbine
Impinging-film cooling is a kind of hybrid cooling, in which the cooling effectiveness would be influenced by the impingement characteristics. Thus, this paper investigates the effects of impinging parameter variations on the performance
of impinging-film cooling. The impinging parameters include jet inclination (30°, 45°, 60°, and 90°), jet-to-slab spacing (1 mm, 1.5 mm, and 2 mm), and jet hole diameter (d = 1 mm, 1.2 mm, and 1.6 mm). In addition, numerical simulation was employed to help in understanding the flow field changes caused by different impinging parameters. The results show that the jet inclination of 90° has higher cooling effectiveness compared to other ones due to the lower turbulent intensities. A smaller jet-to-plate spacing is conducive to the liner cooling attributed to its higher slot velocity. The jet diameter of 1.2 mm shows a great capacity for liner cooling estimated by the cooling effectiveness. An optimal collocation of jet diameter and spanwise hole-to-hole spacing may exist with fixed total jet area according to the cooling effectiveness. The changes of velocity and turbulence intensity distribution due to different impinging parameters account for the difference of cooling effectiveness.