Transient Thermal Analyses of Midwall Cooling and External Cooling Methods for a Gun Barrel

2010 ◽  
Vol 132 (9) ◽  
Author(s):  
Avanish Mishra ◽  
Amer Hameed ◽  
Bryan Lawton
Keyword(s):  
Heat Transfer ◽  
Cooling System ◽  
Thermal Analyses ◽  
Temperature History ◽  
Fe Model ◽  
Gun Barrel ◽  
External Cooling ◽  
Transient Thermal ◽  
Cooling Methods ◽  
Simulation Scheme

Liquid cooling methods are often used for thermal management of a large caliber gun barrel. In this work, transient thermal analyses of midwall-cooled and externally cooled gun barrels were performed. At first, a novel simulation scheme was developed for the computation of the gun barrel temperature history (temperature variation over time), and its experimental validation was performed. In the computational scheme an internal ballistics code, GUNTEMP8.EXE, was developed to simulate the total heat transfer per cycle for the given ammunition parameters. Subsequently, a finite element (FE) model of the barrel was developed in ANSYS 11.0. Heat transfer to the barrel was approximated by an exponentially decaying heat flux. The FE model was solved to compute for barrel temperature history. Simulations were performed for a burst of 9 cycles, and the results were found to agree with the experimental measurements. Subsequently, the simulation scheme was extended to analyze a burst of 40 cycles at 10 shots per minute (spm). Three cases were investigated as follows: (1) a naturally cooled gun barrel, (2) a gun barrel with midwall cooling channels, and (3) an externally cooled gun barrel. Natural cooling was found insufficient to prevent cook-off, whereas midwall and external cooling methods were found to eliminate any possibility of it. In the context of a self-propelled howitzer, a midwall-cooled gun barrel connected to an engine cooling system was also analyzed.

Thermal Analysis of Cooling System in a Gas Turbine Transition Piece

2011 ◽  
Author(s):  
Jun Su Park ◽  
Namgeon Yun ◽  
Hokyu Moon ◽  
Kyung Min Kim ◽  
Sin-Ho Kang ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Gas Turbine ◽  
Thermal Stresses ◽  
Cooling System ◽  
Structural Information ◽  
Thermal Analyses ◽  
Thermal Design ◽  
Transfer Coefficients ◽  
Transition Piece ◽  
Inlet Conditions

This paper presents thermal analyses of the cooling system of a transition piece, which is one of the primary hot components in a gas turbine engine. The thermal analyses include heat transfer distributions induced by heat and fluid flow, temperature, and thermal stresses. The purpose of this study is to provide basic thermal and structural information on transition piece, to facilitate their maintenance and repair. The study is carried out primarily by numerical methods, using the commercial software, Fluent and ANSYS. First, the combustion field in a combustion liner with nine fuel nozzles is analyzed to determine the inlet conditions of a transition piece. Using the results of this analysis, pressure distributions inside a transition piece are calculated. The outside of the transition piece in a dump diffuser system is also analyzed. Information on the pressure differences is then used to obtain data on cooling channel flow (one of the methods for cooling a transition piece). The cooling channels have exit holes that function as film-cooling holes. Thermal and flow analyses are carried out on the inside of a film-cooled transition piece. The results are used to investigate the adjacent temperatures and wall heat transfer coefficients inside the transition piece. Overall temperature and thermal stress distributions of the transition piece are obtained. These results will provide a direction to improve thermal design of transition piece.

Evaluation of Numerical Methods to Predict Temperature Distributions of an Experimentally Investigated Convection-Cooled Gas-Turbine Blade

2017 ◽  
Author(s):  
E. Findeisen ◽  
B. Woerz ◽  
M. Wieler ◽  
P. Jeschke ◽  
M. Rabs
Keyword(s):  
Heat Transfer ◽  
Numerical Methods ◽  
Gas Turbine ◽  
Turbine Blade ◽  
Gas Turbines ◽  
Cooling System ◽  
Fe Model ◽  
Gas Turbine Blade ◽  
Transfer Coefficients ◽  
Temperature Distributions

This paper presents two different numerical methods to predict the thermal load of a convection-cooled gas-turbine blade under realistic operating temperature conditions. The subject of the investigation is a gas-turbine rotor blade equipped with an academic convection-cooling system and investigated at a cascade test-rig. It consists of three cooling channels, which are connected outside the blade, so allowing cooling air temperature measurements. Both methods use FE models to obtain the temperature distribution of the solid blade. The difference between these methods lies in the generation of the heat transfer coefficients along the cooling channel walls which serve as a boundary condition for the FE model. One method, referred to as the FEM1D method, uses empirical one-dimensional correlations known from the available literature. The other method, the FEM2D method, uses three-dimensional CFD simulations to obtain two-dimensional heat transfer coefficient distributions. The numerical results are compared to each other as well as to experimental data, so that the benefits and limitations of each method can be shown and validated. Overall, this paper provides an evaluation of the different methods which are used to predict temperature distributions in convection-cooled gas-turbines with regard to accuracy, numerical cost and the limitations of each method. The temperature profiles obtained in all methods generally show good agreement with the experiments. However, the more detailed methods produce more accurate results by causing higher numerical costs.

High Temperature Overhung Pumps: Cooling Optimization

2005 ◽  
Author(s):  
M. Cipolla
Keyword(s):  
Heat Transfer ◽  
High Temperature ◽  
Cooling System ◽  
Cooling Water ◽  
Experimental Tests ◽  
Thermal Dissipation ◽  
Lubricating Oil ◽  
Fluid Temperature ◽  
External Cooling ◽  
Set Up

A typical industrial application of high temperature pumps involves handling of fluids up to 400 °C. This is critical for pump bearing housing, where thermal dissipation is not effective due to geometric configuration. Therefore, without any external cooling system, bearings and lubricating oil temperatures can exceed allowable values prescribed by both API 610 Reference Standard [1] and bearing manufacturer [2]. Particularly, for a overhung pump, when pumped fluid temperature is above 200 °C, external cooling system is necessary and water is usually used for this purpose. Consequently, water availability must be taken into account when considering pump’s location, which is particularly difficult in desert areas. From these considerations was the idea to enhance the heat transfer of the pump support, in order to avoid any need of cooling water. The problem has been dealt with numerical analysis and experimental tests. First, we have considered the original support in the most critical situation, the stand-by condition, where no forced convection (fan) is effective. From the results pertaining to currently used support, we have got the hints to improve heat transfer by a full redesign. Finally an experimental validation has been set up. The measures gained allow us to validate hypothesis taken into consideration in the numerical simulation.

Gas Turbine Combustor Cooling by Augmented Backside Convection

1979 ◽  
Vol 101 (1) ◽  
pp. 109-115 ◽  
Author(s):  
D. M. Evans ◽  
M. L. Noble
Keyword(s):  
Heat Transfer ◽  
Gas Turbine ◽  
Film Cooling ◽  
Cooling System ◽  
Exhaust Gas ◽  
Confined Space ◽  
Gas Turbine Combustor ◽  
Exhaust Gas Emission ◽  
Cooling Air ◽  
Cooling Methods

Traditionally, gas turbine combustor walls have been cooled by one or more of the various film cooling methods. The current motivation to control exhaust gas emission composition has led to the serious consideration of backside convection wall cooling, where the cooling air is introduced to the main gas stream not prior to the dilution zone. Due to the confined space and the severe nature of the wall cooling problem, it is essential to maximize the heat transfer/pumping power characteristic, which suggests an augmented convection technique. A particular heat transfer design of a combustor cooled by means of transverse rib turbulence promoters applied to the exterior wall of the annular spaces surrounding the primary and secondary zones is described. Analytical methods for designing such a cooling system are reviewed and a comparison between analytical and experimental results is presented.

An Inverse Method for Determining Thermal Load History Which Reduces Transient Thermal Stress

2006 ◽  
Author(s):  
Takuya Ishizaka ◽  
Shiro Kubo ◽  
Seiji Ioka
Keyword(s):  
Heat Transfer ◽  
Thermal Stress ◽  
Temperature Distribution ◽  
Thermal Load ◽  
Inverse Method ◽  
Temperature History ◽  
Load History ◽  
Transient Thermal Stress ◽  
Inner Surface ◽  
Transient Thermal

When high temperature fluid flows into a pipe, a temperature distribution in the pipe induces a thermal stress. It is important to reduce the thermal stress for managing and extending the lives of plants. In this problem heat conduction, elastic deformation, heat transfer, liquid flow should be considered, and therefore the problem is of multidisciplinary nature. In this paper an inverse method is proposed for determining the optimum thermal load history which reduces transient thermal stress considering the multidisciplinary physics. As a typical problem, transient thermal stress in a thin pipe during start-up was treated. It was assumed that the inner surface was heated by liquid flow and the outer surface was insulated for simplicity. The multidisciplinary complex problem was decomposed into a heat conduction problem with given internal wall temperature history, thermal stress problem with given temperature distribution, and heat transfer problem with given heat flux on an inner surface. An analytical solution of the temperature distribution of the radial thickness and the thermal hoop stress distribution was obtained. The maximum inner hoop tensile stress was minimized for the case where inner surface temperature Ts(t) was expressed in terms of the 3rd order polynomial function of time t. Finally, from the temperature distributions, the optimum fluid temperature history was obtained for reducing the transient thermal tensile stress.

scholarly journals Mini Channel Evaporator as MAC Device for Laptop Cooling System

2020 ◽  
Vol 8 (5) ◽  
pp. 2993-2998
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Air Conditioning ◽  
Cooling System ◽  
Laptop Computer ◽  
Air Conditioning System ◽  
Overall Heat Transfer Coefficient ◽  
Flow Through ◽  
Cooling Methods

Laptop computers are known for their compact features which lead to overheating problems. Along with its being compact, laptop computer developers are going for more advance components to be able to run advance computer programs making the laptop do much more which also adds more to the overheating problems of the laptop. Overheated laptops will lead to slower laptop performances, laptop failures and even damaging its components. This problem leads to the development of laptop cooling methods, from fans and blowers and other cooling methods. This study aims to develop a cooling system which involves an air-conditioning system, a Mini Air Conditioning System (MAC System). The key to this study is the fabrication of three(3) mini channel evaporators which has different inner hydraulic diameters but of the same surface area with an overall size and which is smaller than a laptop battery pack. The evaporator for this study was made from a copper block that was fabricated to produce fins and a groove for the refrigerant to flow through the evaporator. The inner hydraulic diameters for the refrigerant to flow through are, 1mm, 2mm, and 3mm. The overall heat transfer coefficient would be determined for each evaporator size. The study showed that the most effective evaporator for cooling the laptop was that of the 3mm evaporator and that using the MAC system is an effective way of cooling a laptop computer. It lowered the temperature of the laptop by 10.65 K versus the setup with no cooler at all and 8.01 K with the setup with a plain cooler. The study also showed that the 3mm evaporator has the highest overall heat transfer coefficient with 73.129W/m2K with a mass flow rate of 0.039 kg/s.

An Inverse Analysis Method for Estimation of Heat Flux and Temperature-Dependence of Heat Transfer Coefficient

2011 ◽  
Author(s):  
Shiro Kubo ◽  
Seiji Ioka
Keyword(s):  
Heat Transfer ◽  
Surface Temperature ◽  
Inverse Method ◽  
Thermal Stresses ◽  
Temperature History ◽  
Inner Surface ◽  
History Of ◽  
Transient Thermal ◽  
The Relationship ◽  
Inverse Analysis Method

Transient thermal stresses develop in pipes during start-up and shut-down. In previous papers the present authors [1–4] proposed an inverse method for determining the optimum thermal inlet liquid temperature history which reduced the maximum transient thermal stress in pipes. The papers considered multiphysics including heat conduction, heat transfer, and elastic deformation. The inverse method used the relationship between inner surface temperature history, transient temperature distribution and transient thermal stresses. The coefficient of heat transfer plays an important role in the evaluation of thermal stress. In this study an inverse method was developed for estimating heat flux and temperature-dependence of the coefficient of heat transfer from the history of the outer surface temperature and the liquid temperature. The method used the relationship between the outer surface temperature and the inner surface temperature. For the regularization of solution the function expansion method was applied in expressing the history of flux on the inner surface. Numerical simulations demonstrated the usefulness of the proposed inverse analysis method. By examining the effect of measurement errors of temperature on the estimation, the robustness of the method was shown.

Transient Thermal Modelling of Whole GT Engine With a Partly Coupled FEM-Fluid Network Approach

2017 ◽  
Author(s):  
Sabrina Giuntini ◽  
Antonio Andreini ◽  
Bruno Facchini ◽  
Marco Mantero ◽  
Marco Pirotta ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Finite Element ◽  
Thermal Analyses ◽  
Heat Transfer Process ◽  
Thermal Modelling ◽  
Transfer Coefficients ◽  
Fully Integrated ◽  
Fluid Network ◽  
Secondary Air ◽  
Transient Thermal

The present work aims at investigating a new methodology developed at Ansaldo Energia, for the transient finite element modelling of the whole engine with an axisymmetric approach. The strong coupling and non linearity in the heat transfer process during transient thermal analyses are handled by a partly coupled scheme. The 2D axisymmetric finite element model includes a dedicated thermal fluid network where fluid-metal temperatures are computed. In the overall procedure the selected finite element solver is a customized version of CalculiX®, while mass flow rates and pressure distributions in each thermal fluid network element are provided by external fluid network solvers in terms of customized time series. This paper represents a first insight about a fully integrated WEM (Whole Engine Modelling) procedure currently under development. Geometrical changes during operation, lead to different fluid properties affecting heat transfer coefficients too. These modified conditions in their turn impact the material temperature and displacements. The future implementation steps will be oriented on the adoption of a customized version of the native CalculiX® fluid network solver with the aim of developing a fully integrated procedure able to take into account the interaction between the secondary air system and the modifications in the clearances and gaps due to the thermal and mechanical loads. In this paper, a detailed description of the procedure will be reported with comprehensive discussions about some fundamental modelling aspects. Preliminary results, related to the first application of the new methodology to the transient thermal modelling of a simplified test case representative of real engine geometries, will be presented.

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