scholarly journals Research on Impact of Cooling Fan’s Geometry on Nozzle’s Heat Load of the Air-Cooled Diesel Engine

2015 ◽  
Vol 9 (1) ◽  
pp. 99-105
Author(s):  
Jun Fu ◽  
Yuan Tang ◽  
Wenhua Yuan ◽  
Guangming Li ◽  
Wei Chen ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Temperature Distribution ◽  
Heat Load ◽  
Needle Valve ◽  
Good Effect ◽  
Cooling Fan ◽  
Installation Angle ◽  
Test Points ◽  
Fan Blade ◽  
The Impact

In order to study the nozzle’s temperature distribution and to reduce its heat load, the heat transfer boundary condition of nozzle has been simplified appropriately, considering the details of the convectional heat transfer inside the nozzle and the needle body contact heat transfer. Results of the simulation with ANSYS software show that the nozzle’s temperature distribution is complicated and high-temperature region are concentrated in the nozzle’s head. Considering the fact that the cooling fan plays an important role in reducing the heat load of air-cooled engine, the test points were reasonably selected to measure the needle valve body’s temperature as well as to seek reasonable cooling fan blade numbers and the blade installation angle for the air outlet in order to improve the thermal load of the nozzle. It was found that the nozzle’s temperature decreases at first but then increased when the fan blade numbers and the blade installation angle for air outlet increased, and the impact of the number of blades on the nozzle’s temperature was more significant than the blade installation angle for the air outlet. With the scheme of the blade installation angle of 132° with respect to the air outlet and with 20 blades, the temperature of the nozzle needle valve’s head and middle decreases to 21 K and 7 K on average compared with the original scheme, which has a good effect on reducing the temperature of the nozzle’s needle valve head, and the temperature gradient between two test points also reduced by 0.65 K/mm on average. It provides a reference for reducing the nozzle’s heat load.

Application of the Transient Heat Transfer Measurement Technique in a Low Aspect Ratio Pin Fin Cooling Channel

2015 ◽  
Author(s):  
Meriam Axtmann ◽  
Jens von Wolfersdorf ◽  
Georg Meyer
Keyword(s):  
Heat Transfer ◽  
Temperature Distribution ◽  
Aspect Ratio ◽  
Measurement Technique ◽  
Thermal Inertia ◽  
Reference Temperature ◽  
Bulk Temperature ◽  
Cooling Channel ◽  
Pin Fin ◽  
The Impact

This study investigates on heat transfer enhancement in pin fin cooling channels. Experiments are conducted in a staggered pin fin array consisting of 15 rows. Heat transfer measurements are conducted in the pin fin cooling channel using the transient liquid crystal technique. The reference temperature is approximated by the fluid bulk temperature, acquired by thermocouples at specific positions. Thermal inertia of the used thermocouples is considered. One other problem that occurs while using relatively long thermocouples in short aspect ratio ducts is the heat conduction along the wires, the so called stem effect. This can lead to erroneous temperature measurements. The impact of the thermocouple immersion length on the temperature measurement is investigated. A detailed assessment of the space and time-wise varying temperature distribution is conducted for the appropriate reference temperature. This paper gives an overview about the experimental setup and the used transient measurement technique. Results are represented in terms of temperature distribution, heat transfer distribution and averaged Nusselt number at the endwall.

Numerical Simulations and Experimental Characterization of Heat Transfer From a Periodic Impingement of Droplets

2011 ◽  
Vol 133 (12) ◽  
Author(s):  
Mario F. Trujillo ◽  
Jorge Alvarado ◽  
Eelco Gehring ◽  
Guillermo S. Soriano
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Temperature Distribution ◽  
Numerical Simulations ◽  
Droplet Impact ◽  
Numerical Comparison ◽  
Temperature Profiles ◽  
Conductive Heat ◽  
Radial Temperature ◽  
The Impact

In this combined experimental and simulation investigation, a stream of HFE-7100 droplets striking a prewetted surface under constant heat flux was studied. An implicit free surface capturing technique based on the Volume-of-Fluid (VOF) approach was employed to simulate this process numerically. Experimentally, an infrared thermography technique was used to measure the temperature distribution of the surface consisting of a 100 nm ITO layer on a ZnSe substrate. The heat flux was varied to investigate the heat transfer behavior of periodic droplet impingement at the solid–liquid interface. In both experiments and simulations, the morphology of the impact zone was characterized by a quasi-stationary liquid impact crater. Comparison of the radial temperature profiles on the impinging surface between the experiments and numerical simulations yielded reasonable agreement. Due to the strong radial flow emanating from successive droplet impacts, the temperature distribution inside the crater region was found to be significantly reduced from its saturated value. In effect, the heat transfer mode in this region was governed by single phase convective and conductive heat transfer, and was mostly affected by the HFE-7100 mass flow rates or the number of droplets. At higher heat fluxes, the minimum temperature, and its gradient with respect to the radial coordinate, increased considerably. Numerical comparison between average and instantaneous temperature profiles within the droplet impact region showed the effect of thermal mixing produced by the liquid crowns formed during successive droplet impact events.

Numerical Investigation of Heat Transfer and Flow Field in Domestic Refrigerators

2013 ◽  
Author(s):  
Chaolei Zhang ◽  
Yongsheng Lian
Keyword(s):  
Heat Transfer ◽  
Temperature Distribution ◽  
Stokes Equations ◽  
Transfer Problem ◽  
Radiation Heat Transfer ◽  
Circulation Pattern ◽  
Boussinesq Approximation ◽  
Navier Stokes ◽  
Air Circulation ◽  
The Impact

Air circulation and temperature distribution inside a domestic refrigerator chamber are two important factors in refrigerator design. They are critical for food quality control and energy saving and are affected by natural/forced convection, radiation and layout of the stored food. Knowledge about the actual air flow and temperature distributions inside a refrigerator is required to improve temperature homogeneity and reduce energy consumption. In present work we numerically study the air circulation and the heat transfer phenomena in a domestic frost-free refrigerator. The inner compartment, the evaporator and the outside thermal insulation foam are considered. The conjugate heat transfer problem is studied by solving the unsteady laminar Navier-Stokes equations using a finite volume method. The Boussinesq approximation is used to model the natural convection. The discrete ordinate method is adopted to take into account the radiation heat transfer between the cold back evaporator and warm surfaces to further understand the impact of radiation. The accuracy of the numerical methods is verified through grid sensitivity analysis and comparison with available numerical and experimental data. Comparisons are made with and without radiation. Our simulations show that radiation significantly changes the temperature distribution and air circulation pattern. The effects of shelf and food stored on the temperature distribution and air circulation are also studied by comparing three configurations: empty refrigerator, empty refrigerator with shelves and loaded refrigerator with food.

Study on Relevant Effects Concerning Heat Transfer of a Convection Cooled Gas Turbine Blade Under Realistic Engine Temperature Conditions

2013 ◽  
Author(s):  
Y. Mick ◽  
B. Wörz ◽  
E. Findeisen ◽  
P. Jeschke ◽  
V. Caspary
Keyword(s):  
Heat Transfer ◽  
Temperature Distribution ◽  
Gas Turbine ◽  
Turbine Blade ◽  
Thermal Stresses ◽  
Cooling System ◽  
Gas Turbine Blade ◽  
Temperature Conditions ◽  
The Impact ◽  
Operating Points

This paper presents a study of the temperature distribution of a convection cooled gas turbine blade under realistic operating temperature conditions using experimental and numerical methods. The analysis is performed experimentally in a linear cascade with exhaust gas from a kerosene combustor. Detailed information at different operating points is taken from the experiments for which conjugate heat transfer (CHT) simulations with ANSYS CFX are carried out. By comparing the experimental and numerical results, the required complexity of the simulations is defined. The subject of this study is a gas turbine rotor blade equipped with a state-of-the-art internal convection cooling system. The test rig enables the examination of the blade at temperatures up to 1300K. The temperature distribution of the blade is measured using thermocouples. The calculations are carried out using the SST turbulence model, the Gamma Theta transition model and the discrete transfer radiation model. The influence of hot gas properties and radiation effects are analysed at three different operating points. This paper gives a quantitative overview of the impact of the mentioned parameters on temperature level and distribution as well as thermal stresses in a convection cooled blade under realistic engine temperature conditions.

scholarly journals Fea-Based Structural Heat Transfer Characteristic of 3-D Orthogonal Woven Composite Subjected to the Non-Uniform Heat Load

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Qian Ma ◽  
Ke Wang ◽  
Shudong Wang ◽  
Hongtao Zhou ◽  
Limin Jin ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Temperature Distribution ◽  
Heat Load ◽  
Transfer Characteristic ◽  
Resin Matrix ◽  
Distribution Characteristics ◽  
Woven Composite ◽  
Element Analysis ◽  
Fabric Reinforcement ◽  
Uniform Heat

Abstract The thermodynamic behavior of 3-D orthogonal woven composite is studied to explore its structural heat transfer mechanism in a non-uniform heat load field based on finite element analysis (FEA). The temperature distribution characteristics of the resin matrix and the fabric reinforcement are observed to compare the heat absorption. Furthermore, the dynamic expansion and distribution characteristics of temperature in the 3-D orthogonal woven composite structure have also been quantitatively studied, together with simultaneously obtaining the path characteristics of the heat transfer in each system (i.e., warp yarns, weft yarns, and Z-yarns). In addition, the spatial temperature distribution characteristics of each yarn system in the fabric reinforcement are also explored. Thus, the structural mechanism of heat conduction for 3-D orthogonal woven composite is obtained.

Conjugate Heat Transfer Simulation of a Radially Cooled Gas Turbine Vane

2004 ◽  
Author(s):  
Bruno Facchini ◽  
Andrea Magi ◽  
Alberto Scotti Del Greco
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Temperature Distribution ◽  
Gas Turbine ◽  
Conjugate Heat Transfer ◽  
Circular Cross Section ◽  
External Temperature ◽  
Turbine Vane ◽  
Heat Transfer Simulation ◽  
The Impact

A 3D conjugate heat transfer simulation of a radially cooled gas turbine vane has been performed using STAR-CD™ code and the metal temperature distribution of the blade has been obtained. The study focused on the linear NASA-C3X cascade, for which experimental data are available; the blade is internally cooled by air through ten radially oriented circular cross section channels. According to the chosen approach, boundary conditions for the conjugate analysis were specified only at the inlet and outlet planes and on the openings of the internal cooling channels: neither temperature distribution nor heat flux profile were assigned along the walls. Static pressure, external temperature and heat transfer coefficient distributions along the vane were compared with experimental data. In addition, in order to asses the impact of transition on heat transfer profile, just the external flow (supposed fully turbulent in the conjugate approach) was separately simulated with TRAF code too and the behaviour of the transitional boundary layer has been analyzed and discussed. Loading distributions were found to be in good agreement with experiments for both conjugate and non conjugate approaches, but, since both pressure and suction side exhibit a typical transitional behavior, HTC profiles obtained without taking into account transition severely overestimate experimental data especially near the leading edge. Results confirm the significant role of transition in predicting heat transfer and, therefore, vane temperature field when a conjugate analysis is performed.

Application of the Transient Heat Transfer Measurement Technique in a Low Aspect Ratio Pin Fin Cooling Channel

2015 ◽  
Vol 137 (12) ◽  
Author(s):  
Meriam Axtmann ◽  
Jens von Wolfersdorf ◽  
Georg Meyer
Keyword(s):  
Heat Transfer ◽  
Temperature Distribution ◽  
Aspect Ratio ◽  
Measurement Technique ◽  
Thermal Inertia ◽  
Reference Temperature ◽  
Bulk Temperature ◽  
Cooling Channel ◽  
Pin Fin ◽  
The Impact

This study investigates on heat transfer enhancement in pin fin cooling channels. Experiments are conducted in a staggered pin fin array consisting of 15 rows. Heat transfer measurements are conducted in the pin fin cooling channel using the transient liquid crystal technique. The reference temperature is approximated by the fluid bulk temperature, acquired by thermocouples at specific positions. Thermal inertia of the used thermocouples is considered. One other problem that occurs while using relatively long thermocouples in short aspect ratio ducts is the heat conduction along the wires, the so-called stem effect. This can lead to erroneous temperature measurements. The impact of the thermocouple immersion length on the temperature measurement is investigated. A detailed assessment of the space and timewise varying temperature distribution is conducted for the appropriate reference temperature. This paper gives an overview about the experimental setup and the used transient measurement technique. Results are represented in terms of temperature distribution, heat transfer distribution, and averaged Nusselt number at the endwall.

Rotor Blade Heat Transfer Characteristics for High Pressure Turbine Stage Under Inlet Temperature and Velocity Traverses

2014 ◽  
Author(s):  
A. Rahim ◽  
L. He ◽  
E. Romero
Keyword(s):  
Heat Transfer ◽  
High Pressure ◽  
Heat Load ◽  
Inlet Temperature ◽  
Turbine Stage ◽  
Heat Transfer Characteristics ◽  
Lean Burn ◽  
Transfer Characteristics ◽  
Hot Streak ◽  
The Impact

One of the key considerations in high pressure (HP) turbine design is the heat load experienced by rotor blades. The impact of turbine inlet non-uniformities on the blades in the form of combined temperature and velocity traverses, typical for a lean burn combustor exit, has rarely been studied. For general HP turbine aerothermal designs, it is also of interest to understand how the behavior of a lean burn combustor traverses (hot streak and swirl) might contrast with those for rich burn combustion (largely hot streak only). In the present work, a computational study has been carried out on the aerothermal performance of a HP turbine stage under non-uniform temperature and velocity inlet profiles. The analyses are primarily conducted for two combined hot streak and swirl inlets, with opposite swirl directions. In addition, comparisons are made against a hot streak only case and a uniform inlet. The effects of three NGV shape configurations are investigated; namely, straight, compound lean (CL) and reverse compound lean (RCL). The present results show that there is a qualitative change in the roles played by heat transfer coefficient (HTC) and fluid driving (‘adiabatic wall’) temperature, Taw. It has been shown that the blade heat load distribution for a uniform inlet is dominated by HTC, whilst for a hot streak only case it is wholly influenced by Taw. However, in contrast to the hot streak only case, the case with a combined hot streak and swirl shows a role reversal with the HTC being dominant in determining the heat load. Additionally, it is seen that the swirling flow radially redistributes the hot fluid within the NGV passage considerably, leading to a much ‘flatter’ rotor inlet temperature profile compared to its hot streak only counterpart. Further, the rotor heat transfer characteristics for the cases with the combined traverses are shown to be strongly dependent on the NGV shaping and the inlet swirl direction, indicating the potential for future design space exploration. The present findings underline the need to clearly define relevant combustor exit temperature and velocity profiles when designing and optimizing NGVs for HP turbine aerothermal performance.

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