Multi-Objective CFD Optimisation of Shaped Hole Film Cooling With Mesh Morphing

2015 ◽  
Author(s):  
D. Proietti ◽  
A. Pranzitelli ◽  
G. E. Andrews ◽  
M. E. Biancolini ◽  
D. B. Ingham ◽  
...  
Keyword(s):  
Design Of Experiments ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Film Cooling ◽  
Maximum Deviation ◽  
Geometrical Parameters ◽  
Shape Parameters ◽  
Cooling Effectiveness ◽  
Adiabatic Cooling

A Computational Fluid Dynamics (CFD) optimisation of a single row of film cooling holes was performed. The aim was to achieve the highest adiabatic cooling effectiveness while minimising the coolant mass flow rate. The geometry investigated by Gritsch et al. [1] was the baseline model. It consisted of a row of cylindrical, 30° inclined holes, with a mainstream inlet Mach number of 0.6, a blowing ratio of 1 and a plenum for the upstream cooling air flow. The predictions agreed with the experimental data with a maximum deviation of 6%. The geometry was then optimised by varying three shape parameters: the injection angle, the lateral hole expansion angle and the downstream compound hole angle. A goal driven optimisation approach was based on a design of experiments table. The minimisation of the coolant mass flow together with the maximisation of the minimum and average cooling effectiveness were the optimisation objectives. The shape modifications were performed directly in the ANSYS Fluent CFD solver by using the software RBF Morph in the commercial software platform ANSYS Workbench. There was no need to generate a new geometry and a new computational mesh for each configuration investigated. The dependency of the average effectiveness along the plane centreline on the three geometrical parameters was investigated based on the metamodel generated from the design of experiments results. The goal driven optimisation led to the optimal combination of the three shape parameters to minimise the coolant flow without reducing the cooling effectiveness. The best results were obtained for a geometry with 20° hole angle and 7.5° compound angle injection, leading to a reduction of 15% in the coolant mass flow rate for an enhanced adiabatic cooling effectiveness. The results also showed the preponderance of the centreline angle over the other two parameters.

A One-Dimensional Analytical Method for Turbine Blade Preliminary Cooling Design

2016 ◽  
Author(s):  
Chen Li ◽  
Jian-jun Liu
Keyword(s):  
Mass Flow Rate ◽  
Turbine Blade ◽  
Mass Flow ◽  
Flow Rate ◽  
Film Cooling ◽  
Three Dimensional ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
One Dimensional ◽  
Cooling Design

The turbine blade cooling design is a complex procedure including one-dimensional preliminary cooling design, detailed two-dimensional design and fluid network analyses, and three-dimensional conjugate heat transfer and FEM predictions. Frequent alteration and modification of the cooling configurations make it unpractical to obtain all of three-dimensional design results quickly. Preliminary cooling design deals mainly with the coolant requirements and can be knitted into fluid network to look up the expected cooling structural style to promote three-dimensional geometry design. Previous methods to estimate the coolant requirements of the whole turbine blade in the preliminary cooling design were usually based on the semi-empirical air-cooled blade data. This paper combines turbine blade internal and external cooling, and presents a one-dimensional theoretical analytical method to investigate blade cooling performance, assuming that the coolant temperature increases along the blade span. Firstly, a function of non-dimensional cooling mass flow rate is derived to describe the new relationship between adiabatic film cooling effectiveness and overall cooling effectiveness. Secondly, a new variable related to film cooling is found to estimate the required adiabatic film cooling effectiveness without using the empirical correlations. Finally, a theoretical calculation about the relationship between non-dimensional cooling mass flow rate and overall cooling effectiveness well corresponds to semi-empirical air-cooled blade data within regular range of cooling efficiency. The currently proposed method is also a useful tool for the blade thermal analysis and the sensitivity analysis of coolant requirements to various design parameters. It not only can provide all the possible options at the given gas and coolant inlet temperatures to meet the design requirement, but also can give the third boundary conditions for calculating the blade temperature field. It’s convenient to use the heat transfer characteristic of internal cooling structures to estimate the coolant mass flow rate and the channel hydraulic diameter for both convection cooling and film cooling.

scholarly journals Determination of critical operating and geometrical parameters in diesel injectors through one dimensional modelling, design of experiments and an analysis of variance

2017 ◽  
Vol 232 (13) ◽  
pp. 1762-1781 ◽  
Author(s):  
Francisco J Salvador ◽  
Marcos Carreres ◽  
Marco Crialesi-Esposito ◽  
Alejandro H Plazas
Keyword(s):  
Design Of Experiments ◽  
Mass Flow Rate ◽  
Analysis Of Variance ◽  
Mass Flow ◽  
Flow Rate ◽  
Control Volume ◽  
Geometrical Parameters ◽  
One Dimensional ◽  
Injection Process ◽  
Rate Profile

In this paper, a design of experiments and a statistical analysis of variance (ANOVA) are performed to determine the parameters that have more influence on the mass flow rate profile in diesel injectors. The study has been carried out using a one dimensional model previously implemented by the authors. The investigation is split into two different parts. First, the analysis is focused on functional parameters such as the injection and discharge pressures, the energizing time and the fuel temperature. In the second part, the influence of 37 geometrical parameters, such as the diameters of hydraulic lines, calibrated orifices and internal volumes, among others, are analysed. The objective of the study is to quantify the impact of small variations in the nominal value of these parameters on the injection rate profile for a given injector operating condition. In the case of the functional parameters, these small variations may be attributed to possible undesired fluctuations in the conditions that the injector is submitted to. As far as the geometrical and flow parameters are concerned, the small variations studied are representative of manufacturing tolerances that could influence the injected mass flow rate. As a result, it has been noticed that the configuration of the inlet and outlet orifices of the control volume, together with the discharge coefficient of the inlet orifice, among a few others, play a remarkable role in the injector performance. The reason resides in the fact that they are in charge of controlling the behaviour of the pressure in the control volume, which importantly influences injector dynamics and therefore the injection process. Variations of only 5% in the diameter of these orifices strongly modify the shape of the rate of injection curve, influencing both the injection delay and the duration of the injection process, consequently changing the total mass delivered.

Film Cooling Performance Improvement With Optimized Hole Arrangements on Pressure Side Surface of Nozzle Guide Vane: Part II — Experimental Validation

2016 ◽  
Author(s):  
Dong-Ho Rhee ◽  
Young Seok Kang ◽  
Bong Jun Cha ◽  
Jeong-Seek Kang ◽  
Sanga Lee ◽  
...  
Keyword(s):  
Mass Flow Rate ◽  
Performance Improvement ◽  
Mass Flow ◽  
Flow Rate ◽  
Film Cooling ◽  
Side Surface ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Percentage Points ◽  
Nozzle Guide

In the present study, the optimized configurations of film cooled turbine guide vanes proposed in Part I were validated experimentally and the effect of coolant mass flow rate on the performance was examined for those optimized configurations. A set of tests were conducted using an annular sector transonic turbine cascade test facility in Korea Aerospace Research Institute. The mainstream and the secondary air for cooling are supplied by 500 hp and 50 hp compressors, respectively, and the mainstream was heated approximately 20°C above the secondary flow by 300kW heater. To measure the film cooling effectiveness on the pressure side surface, the transient measurement method was used using a FLIR infrared camera system. The test section has five nozzle guide vanes with four passages. The three times scaled-up vane model is manufactured by a stereolithography method. The tests were conducted at mainstream exit Reynolds number based on the chord of 2.2×106 and the coolant mass flow rate ranging from 5 to 13% of the mainstream. The flow periodicity in the cascade passage was verified by surface static pressure measurements. The results showed that the optimized cases present better cooling effectiveness values in the overall region. The effect of coolant mass flow rate also presents the same trend. Comparison with the CFD results shows that the CFD results over-predict film cooling effectiveness by 10∼20 percentage points for baseline and 17∼23 percentage points for the optimized cases. This is probably partly due to the discrepancy of operating conditions such as inlet boundary condition and density ratio and partly due to the limitation of numerical method used in the optimization such as coarse grid near the surface. However, a quite good agreement is obtained qualitatively, which means the optimization process can be utilized as a reliable and efficient method for film cooling performance improvement.

An Experimental Investigation of Full-Coverage Film Cooling Effectiveness and Heat Transfer Coefficient of a Turbine Guide Vane in a Linear Transonic Cascade

2016 ◽  
Author(s):  
Zhong-yi Fu ◽  
Hui-ren Zhu ◽  
Cun-liang Liu ◽  
Cong Liu ◽  
Zheng Li
Keyword(s):  
Heat Transfer ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Film Cooling ◽  
Rate Ratio ◽  
Flow Rate Ratio ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Mass Flow Rate Ratio

This paper experimentally investigates the film cooling performance of an enlarged turbine guide vane with full-coverage cylindrical hole film cooling in short duration transonic wind tunnel which can model realistic engine aerodynamic conditions and adjust inlet Reynolds number and isentropic exit Mach number independently. The effects of mass flow rate ratio (MFR=4.83%∼8.83%), inlet Reynolds number (Rein= 1.7×105∼5.7×105), and isentropic exit Mach number (Mais=0.81∼1.01) are investigated. There are five rows of cylindrical film cooling holes on the pressure side and four such rows on the suction side respectively. Another four rows of cylindrical holes are provided on the leading edge to obtain a showerhead film cooling. The surface heat transfer coefficient and adiabatic film cooling effectiveness are derived from the surface temperatures measured by the thermocouples mounted in the middle span of the vane surface based on transient heat transfer measurement method. Mass flow rate ratio is shown to have a significant effect on film cooling effectiveness. The increase of mass flow rate ratio increases film cooling effectiveness on pressure side, while increasing this factor has opposite effect on film cooling effectiveness on the suction side. At the same mass flow rate ratio, increasing the Reynolds number can enhance the film cooling performance, the expectation is that at low mass flow rate ratio condition increasing the Reynolds number decreases film cooling effectiveness on the pressure side. The heat transfer coefficient increases with the mass flow rate ratio increasing on both pressure and suction side. At middle and high inlet Reynolds number condition, in the region of 0.4<s<0.6 on suction side, the coolant weakens heat transfer adversely.

Numerical Study of Supersonic Film Cooling in Diverging Section of Nuclear Rocket Laval Nozzle

2018 ◽  
Author(s):  
Xiaokai Sun ◽  
Ping Ye ◽  
Peixue Jiang ◽  
Wei Peng ◽  
Jie Wang
Keyword(s):  
Mach Number ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Film Cooling ◽  
Laval Nozzle ◽  
Numerical Study ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Nuclear Rocket

Nuclear rockets with specific impulse have obvious advantages by greatly reducing the mass of the propellant and potentially decreasing the cost of launching material from the earth’s surface. Nuclear thermal rockets use hydrogen propellant with coolant exit temperature of near 3000 K, which is very high, so the cooling of airframe surfaces in the vicinity of the exhaust is needed, of which film cooling is an effective method. Most of previous studies mainly focus on the film cooling effectiveness using two dimensional backward-facing step model, however, the nuclear rocket exhaust using the converging-diverging Laval nozzle, so the film cooling would be different. The present study numerically investigated the influence of coolant Mach number, coolant inlet height on supersonic film cooling in the diverging section of Laval nozzle, while keeping the coolant mass flow rate constant, with the results showing that: increasing the coolant inlet Mach number and the coolant inlet height can increase the film cooling effectiveness; for the same coolant mass flow rate, reducing the coolant inlet height and increasing the inlet Mach number improves film cooling effectiveness.

Influence of Coolant Jet Pulsation on the Convective Film Cooling of an Adiabatic Wall

2016 ◽  
Vol 139 (2) ◽  
Author(s):  
Qaiser Sultan ◽  
Gildas Lalizel ◽  
Matthieu Fénot ◽  
Eva Dorignac
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Film Cooling ◽  
Convective Heat Transfer Coefficient ◽  
Time Interval ◽  
Adiabatic Wall ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
The Impact

This study investigates the effects of sinusoidal pulsations externally imposed to an oblique round jet. The effectiveness of film coverage of an adiabatic wall onset for a thermally uniform bulk flow is presented in the perspective of gas turbine film cooling. For the injectant fluid, both the temperature and the mass flow rate are controlled prior to entrance to the periodic forcing system using a loudspeaker drive. The characteristic film cooling parameters including the blowing ratios and the temperature ratio are maintained at M=ρiUi/ρ∞U∞ = 0.65, 1, and 1.25, and Ti/T∞=2 respectively. The injection fluid is pulsated to a nondimensionalized frequency of St=f⋅d/U = 0, 0.2, 0.3, and 0.5. In the present investigation, the impact of injectant film modulation is figured out by analyzing the velocity fields measured by a system of time-resolved particle image velocimetry (TR-PIV), as well as analyzing the adiabatic wall temperature and the convective heat transfer coefficient measured by a system of infrared thermography. The overall film-cooling effectiveness is revealed by the time-averaged analysis, in which altered time-averaged jet trajectories and wake behavior are focused. It is observed that the pulsations tend to result in lower effectiveness when the flow remained attached to the wall in steady blowing case. In steady blowing cases with jet liftoff, such as for M= 1.25, rendering low-frequency pulsation helps in increasing film-cooling effectiveness due to the discharge of lower mass flow rate coolant during the significant time interval of the respective pulse cycle.

scholarly journals Flow Characteristic of Hydraulic Headbox Based on Complementary Pulp Distribution

2015 ◽  
Vol 9 (1) ◽  
pp. 733-738
Author(s):  
Liu Wei ◽  
Ji Xiaohui
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Flow Characteristic ◽  
Fluid Dynamic ◽  
Maximum Deviation ◽  
Improve Performance ◽  
Central Section ◽  
Mixing Chamber ◽  
Two Sides

In order to study the effect of complementary pulp distribution, computational fluid dynamic (CFD) was used to research on flow characteristic of hydraulic headbox based on complementary pulp distribution. Mass flow rate out of mixing chamber and velocity distribution at slice of headbox were experimented. The results show that because of simplified design, there was a little gradient of velocity and pressure which caused non uniform distribution of mass flow rate out of branch pipes. Distribution of mass flow rate was ascended from inlet of header to outlet and the deviation was - 2.33% and 1.82%. There was intense interference between the jets of branch pipes in mixing chamber and the jets could be sufficiently and complementarily mixed in rows and ranks. But the interference in the jets caused the accumulation of the jets in the central section of mixing chamber and mass flow rate out of mixing chamber in the center was higher than the two sides, and the maximum deviation was 0.538%. Distribution of velocity of pulp stock at slice of headbox was very gentle and curve of distribution presented only slight fluctuation. The maximum deviation of velocity was only 0.175%. From the results of the experiment, the test values of mass flow rate out of mixing chamber were inosculated with the calculated values and tested values of velocity at the slice of headbox were in accordance with the calculated values. The results of experiment explained that the method of complementary pulp distribution was reasonable and could obviously improve performance of pulp distribution of hydraulic headbox.

Background-Grid Based Mapping Approach to Film Cooling Meshing: Part III — Applications in a Full-Cooled Turbine Vane

2020 ◽  
Author(s):  
Ruiqin Wang ◽  
Xin Yan
Keyword(s):  
Gas Turbine ◽  
Turbine Blade ◽  
Mass Flow ◽  
Flow Rate ◽  
Film Cooling ◽  
Design Flow ◽  
Cooling Effectiveness ◽  
Cooling Performance ◽  
Film Cooling Effectiveness ◽  
Structured Grids

Abstract To cool a high-pressure gas turbine blade, many rows of cooling holes with different arrangements and configurations are manufactured to achieve higher cooling effect and lower aerodynamic loss. To evaluate the heat transfer and film cooling effect in the full-cooled turbine blade, efficient numerical simulations are required in the design and performance optimization processes. From the view of numerical accuracy, the structured grids have to be employed because of higher resolution in flow and heat transfer than the unstructured grids. Because many splitting, attaching and merging manipulations are involved in meshing the cooling features and curved boundaries, it is very complex and time-consuming for a researcher to generate multi-block structured grids for a full-cooled gas turbine blade. As a result, in the industrial applications, almost all researchers preferred to generate unstructured grids instead of structured grids for the full-cooled blade. Unlike the previous research, the aim of this study is to apply the Background-Grid Based Mapping (BGBM) method proposed in Part I to generate multi-block structured grids for a full-cooled gas turbine vane. With the strategy of BGBM method, meshes were conveniently generated in the computational space with simple geometrical features and plain interfaces, and then were mapped back into physical space to obtain the multi-block structured grids which can be used for numerical simulations. With the experimental data, the present numerical methods and BGBM strategy were carefully validated. Then, the flow and film cooling performance in the full-cooled NASA GE-E3 nozzle guided vane were numerically investigated. The effects of coolant mass flow rate and land extensions on film cooling effectiveness were discussed. The results show that film cooling effectiveness near the stagnation point is the lowest and film cooling effectiveness on the pressure side is slightly higher than that on the suction side. When the coolant mass flow rate increases up to the value of 1.5 design flow, the relative outflow mass flow rates of cooling hole arrays and slots are no longer affected by the increase of the coolant flow rate. At half design flow, the outflow mass flow rates of No.5 hole-array to No.10 hole-array are almost zero, and the area-averaged film cooling effectiveness on vane surface is as low as 0.268. Compared with the cases of half design flow and double design flow, better film cooling performance is obtained in the cases of design flow and 1.5 design flow. Compared with the vane without lands, the area-average cooling effectiveness on vane surface is slightly higher for the vane with lands. Land extensions have a considerable influence on film cooling performance in the cutback region.

Capillary trees for passive pumping water

2021 ◽  
Author(s):  
Xuewei Zhang ◽  
Sylvie Lorente
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Capillary Flow ◽  
Search Algorithm ◽  
Geometrical Parameters ◽  
Maximum Mass ◽  
Capillary Flows ◽  
The Impact ◽  
Fixed Network

Abstract Capillary flows are an attractive feature for passive water harvesting as they require no external driving force to pull the fluid out within the capillary network. Here we analyze the architecture of capillary flow networks in steady state, and the impact of the network morphology on the maximum mass flow rate that can be extracted for a fixed network volume and fixed network footprint. We develop a search algorithm to test the possible location of all the junction and bifurcation nodes and the changes in diameter ratios with the objective of obtaining the maximum mass flow rate from the network. We define the Capillary Strength CS as a local indicator to determine the geometrical parameters of each conduct that allow to sustain the overall mass flow rate. It is shown that the diameter ratio of connected tubes for maximum mass flow rate depends on the distance from the network outlet, and therefore does not follow the Hess-Murray’s law. The superiority of dendritic architectures in the roots and canopy branches of the capillary trees is demonstrated.

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