Variations of cooling performance on turbine vanes due to incipient particle deposition

2021 ◽  
pp. 095765092110105
Author(s):  
Xing Yang ◽  
Zihan Hao ◽  
Zhenping Feng
Keyword(s):  
Mass Flow ◽  
Film Cooling ◽  
Particle Deposition ◽  
Early Stage ◽  
High Mass ◽  
Cooling Performance ◽  
Turbine Vanes ◽  
Changing Patterns ◽  
Low Mass ◽  
Grid Nodes

In this paper, to demonstrate the deposition effects on cooling performance, the changing patterns of film cooling due to particle deposition are numerically investigated on a turbine vane that is cooled by an array of film-holes. The uniqueness of this work is addressing the cooling performance at an early deposition stage, in which deposits are relatively slight. The build-ups of the deposits are simulated by moving grid nodes on the wall boundaries. Results show that in addition to particle velocity, the blowing conditions and wall temperatures are two important factors to determine the deposition patterns. Increasing coolant-to-mainstream mass flow ratios and lowering wall temperatures can help inhibit the growth of deposits. In addition, the modifications of the vane profile due to incipient deposition are completely different from those with excessive deposition. Although flow fields are less sensitive to the early-stage deposits in the subsonic vane passage, cooling effectiveness is significantly changed and the changes are linked to the mass flow ratios. Compared to the cooling performance from a non-deposition case, reduced cooling performance due to incipient deposition is found at a low mass flow ratio of 1.09%, while cooling performance is improved at moderate and high mass flow ratios of 1.64% and 2.06%.

scholarly journals Simulation and Modeling of Flow in a Gas Compressor

2015 ◽  
Vol 2015 ◽  
pp. 1-7
Author(s):  
Anna Avramenko ◽  
Alexey Frolov ◽  
Jari Hämäläinen
Keyword(s):  
Steady State ◽  
Mass Flow ◽  
Gas Flow ◽  
Simulation Method ◽  
High Mass ◽  
Ansys Fluent ◽  
Flow Rates ◽  
Mass Flow Rates ◽  
Low Mass ◽  
Flow Through

The presented research demonstrates the results of a series of numerical simulations of gas flow through a single-stage centrifugal compressor with a vaneless diffuser. Numerical results were validated with experiments consisting of eight regimes with different mass flow rates. The steady-state and unsteady simulations were done in ANSYS FLUENT 13.0 and NUMECA FINE/TURBO 8.9.1 for one-period geometry due to periodicity of the problem. First-order discretization is insufficient due to strong dissipation effects. Results obtained with second-order discretization agree with the experiments for the steady-state case in the region of high mass flow rates. In the area of low mass flow rates, nonstationary effects significantly influence the flow leading stationary model to poor prediction. Therefore, the unsteady simulations were performed in the region of low mass flow rates. Results of calculation were compared with experimental data. The numerical simulation method in this paper can be used to predict compressor performance.

Computational Fluid Dynamics Performance Estimation of Turbo Booster Vacuum Pump

2003 ◽  
Vol 125 (3) ◽  
pp. 586-589 ◽  
Author(s):  
H.-P. Cheng ◽  
C.-J. Chen , ◽  
P.-W. Cheng ,
Keyword(s):  
Fluid Dynamics ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Vacuum Pump ◽  
Performance Estimation ◽  
High Mass ◽  
Rotor Speed ◽  
Low Mass ◽  
Pump Inlet

The CFD performance estimation of turbo booster vacuum pump shows the axial vortex and back flow is evident when the mass flow rate is increased. The pressure is increased from the pump inlet to the outlet for the low mass flow rate cases. But for high mass flow rate cases, the pressure is increased until the region near the end of the rotor then decreased. The calculated inlet pressure, compression ratio, and pumping speed is increased, decreased, and decreased, respectively, when the mass flow rate is increased. The pumping speed is increased when the rotor speed is increased.

Numerical Investigation of the Effect of Inlet Flow Angle on Film Cooling Performance for the Blade Tip With Suction Surface Squealer Rim

2019 ◽  
Author(s):  
Zhiqiang Yu ◽  
Jianjun Liu ◽  
Chen Li ◽  
Baitao An
Keyword(s):  
Mass Flow ◽  
Film Cooling ◽  
Incidence Angle ◽  
Leading Edge ◽  
Flow Ratio ◽  
Suction Surface ◽  
Cooling Performance ◽  
Tip Leakage ◽  
Pressure Surface ◽  
Mass Flow Ratio

Abstract Numerical investigations have been performed to study the effect of incidence angle on the aerodynamic and film cooling performance for the suction surface squealer tip with different film-hole arrangements at τ = 1.5% and BR = 1.0. Meanwhile, the full squealer tip as baseline is also investigated. Three incidence angles at design condition (0 deg) and off-design conditions (± 7 deg) are investigated. The suction surface, pressure surface, and the camber line have seven holes each, with an extra hole right at the leading edge. The Mach number at the cascade inlet and outlet are 0.24 and 0.52, respectively. The results show that the incidence angle has a significant effect on the tip leakage flow characteristics and coolant flow direction. The film cooling effectiveness distribution is altered, especially for the film holes near the leading edge. When the incidence angle changes from +7 deg to 0 and −7 deg, the ‘re-attachment line’ moves downstream and the total tip leakage mass flow ratio decreases, but the suction surface tip leakage mass flow ratio near leading edge increases. In general, the total tip leakage mass flow ratio for suction surface squealer tip is 1% greater than that for full squealer tip at the same incidence angle. The total pressure loss coefficient of suction surface squealer tip is larger than that for full squealer tip. The full squealer tip with film holes near suction surface and the suction surface squealer tip with film hole along camber line show high film cooling performance, and the area averaged film cooling effectiveness at positive incidence angle +7 deg is higher than that at 0 and −7 deg. The coolant discharged from film holes near pressure surface only cools narrow region near pressure surface.

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.

Numerical Study of the Film Cooling With Discrete-Hole Arrangement on a Cut Back Squealer Blade Tip

2015 ◽  
Author(s):  
Xiang Zhang ◽  
Zhong Yang ◽  
Shuqing Tian ◽  
Haiteng Ma
Keyword(s):  
Mass Flow ◽  
Film Cooling ◽  
Numerical Study ◽  
Pressure Side ◽  
Transfer Coefficients ◽  
Cooling Effectiveness ◽  
Cooling Performance ◽  
Film Cooling Effectiveness ◽  
Blade Tip ◽  
Cavity Floor

Detailed numerical investigations of film cooling effectiveness are conducted for the holes on the tip cavity floor and near the tip pressure side. The tested blade tip is a squealer with the trailing rim wall cut to allow the accumulated coolant in the cavity to escape and cool the trailing edge. The heat transfer coefficients on the un-cooled flat and cutback squealer blade tip are studied with numerical and experimental methods. Three dust purging holes with different diameters are arranged along the camber line, which forms the basic cooled case (PG case). Additional six tip cavity holes are arranged on cavity floor near the suction side rim (PG-TF case). Another row of angled twenty-one holes is arranged along the pressure side just below the tip based on the PG case (PG-PSF case). The coolant supply pressure ratios are controlled to be 1, 1.11, and 1.22 respectively, offering local blowing ratio from 0 to 2.5. Results show that the dust purging flow cooling performance increases with the cavity depth. Discrete holes on the cavity floor offer a well-distributed coolant, which refines the cooling effect on the cavity floor. The PG-PSF case with cooling holes on the pressure side has the best overall cooling performance with more coolant consumed, when PR ≥ 1.22. However, maintaining the same coolant mass flow the PG-TF case has the best cooling performance, and the margin between PG-TF and PG-PSF case decreases with mass flow. The moving shroud cases reveal that blade movement will cause significant negative impacts on film cooling effectiveness.

scholarly journals Computational Investigation of Flows in Diffusing S-shaped Intakes

10.14311/262 ◽  
2001 ◽  
Vol 41 (4-5) ◽  
Author(s):  
R. Menzies
Keyword(s):  
Unsteady Flow ◽  
Turbulence Model ◽  
Mass Flow ◽  
Turbulence Models ◽  
High Mass ◽  
Complex Flow ◽  
Choked Flow ◽  
Sst Turbulence Model ◽  
Low Mass ◽  
Flow Case

This paper examines the flow in a diffusing s-shaped aircraft air intake using computational fluid dynamics (CFD) simulations. Diffusing s-shaped ducts such as the RAE intake model 2129 (M2129) give rise to complex flow patterns that develop as a result of the offset between the intake cowl plane and engine face plane. Euler results compare favourably with experiment and previous calculations for a low mass flow case. For a high mass flow case a converged steady solution was not found and the problem was then simulated using an unsteady flow solver. A choked flow at the intake throat and complex shock reflection system, together with a highly unsteady flow downstream of the first bend, yielded results that did not compare well with previous experimental data. Previous work had also experienced this problem and a modification to the geometry to account for flow separation was required to obtain a steady flow.RANS results utilising a selection of turbulence models were more satisfactory. The low mass flow case showed good comparison with experiment and previous calculations. A problem of the low mass flow case is the prediction of secondary flow. It was found that the SST turbulence model best predicted this feature. Fully converged high mass flow results were obtained. Once more, SST results proved to match experiment and previous computations the best. Problems with the prediction of the flow in the cowl region of the duct were experienced with the S-A and k-w models. One of the main problems of turbulence closures in intake flows is the transition of the freestream from laminar to turbulent over the intake cowl region. It is likely that the improvement in this prediction using the SST turbulence model will lead to more satisfactory results for both high and low mass flow rates.

Experimental Study on the Effects of Slot Jet on Film Cooling Performance in the Cascade Endwall With Purge Flow

2019 ◽  
Author(s):  
Yao Yunjia ◽  
Zhu Peiyuan ◽  
Tao Zhi ◽  
Song Liming ◽  
Li Jun
Keyword(s):  
Mass Flow ◽  
Film Cooling ◽  
Flow Ratio ◽  
Cooling Effectiveness ◽  
Cooling Performance ◽  
Film Cooling Effectiveness ◽  
Ejection Angle ◽  
Purge Flow ◽  
Endwall Film Cooling ◽  
Mass Flow Ratio

Abstract Based on the infrared temperature measurement technology, in this paper, the effect of the purge flow from the upstream slot on the film cooling performance of the annular cascade endwall was studied experimentally. GE‘s E3 turbine first stage stator blades is selected as the experimental reference blade type in this experiment. In the current experiment, effects of different slot locations, slot ejection angles and slot profiles on the endwall film cooling effectiveness were taken into account. Under the influence of endwall secondary flow, the film cooling is mainly concentrated on the front part of the channel and close to the suction side of the blade, while there is almost no cooling effect close to the pressure side of the blade in the channel. With the increase of the distance between the blade leading edge and the slot, the endwall film cooling performance is reduced. While the distance increasing from 0.15Cx to 0.45Cx, and the peak endwall film cooling effectiveness is reduced by 78%, 68% and 58% respectively when the mass flow ratio (MFR) is 1.0%, 1.5%, and 2.0%. As the slot ejection angle is reduced, the endwall film cooling performance can be effectively improved. When the slot ejection angle increased from 45° to 90°, the peak endwall film cooling effectiveness decreases by 17%, 15%, and 13% respectively at the mass flow ratio (MFR) = 1.0%,1.5% and 2.0%. And the convergent slot can effectively improve the endwall cooling film formed by slot jet compared to the reference slot. When the mass flow ratio are MFR = 1.0%, 1.5%, and 2.0%, the peak endwall film cooling effectiveness at the convergent slot is increased by 50%, 20%, and 15% comparing to the reference slot.

A Comparative Investigation of Two Types of MHPA Flat-Plate Solar Air Collector Based on Exergy Analysis

2017 ◽  
Vol 139 (5) ◽  
Author(s):  
T. T. Zhu ◽  
Y. H. Diao ◽  
Y. H. Zhao ◽  
C. Ma ◽  
T. Y. Wang ◽  
...  
Keyword(s):  
Flat Plate ◽  
Mass Flow ◽  
Exergy Analysis ◽  
Comparative Investigation ◽  
Exergy Efficiency ◽  
High Mass ◽  
Condenser Section ◽  
Flow Rates ◽  
Mass Flow Rates ◽  
Low Mass

In this study, a comparative investigation of two types of microheat pipe array (MHPA) flat-plate solar air collectors (FPSAC) based on exergy analysis has been conducted. The thermal performance of MHPA-type solar air collectors (SACs) with two different shaped fins is experimentally evaluated. A detailed parametric study is also conducted to examine the effects of various fins, operation parameters, and inlet air temperature at different mass flow rates on thermal and exergy efficiencies. Results indicated that using V-shaped slotted fins at the specified range of mass flow rates can enhance exergy efficiency. Exergy efficiency can be considered as the main criterion to evaluate the performance of MHPA FPSACs. Attaching V-shaped slotted fins on the condenser section of MHPA is more effective than attaching rectangular fins at high mass flow rates. By contrast, the latter is more effective than the former at low mass flow rates.

scholarly journals Prediction of Film Cooling by Discrete-Hole Injection

1993 ◽  
Author(s):  
Jian-ming Zhou ◽  
Martha Salcudean ◽  
Ian S. Gartshore
Keyword(s):  
Mass Flow ◽  
Film Cooling ◽  
Computational Method ◽  
Hole Injection ◽  
Main Stream ◽  
Cooling Process ◽  
Double Row ◽  
Local Flow ◽  
Cooling Performance ◽  
Film Cooling Effectiveness

This paper presents a study on film cooling performance resulting from injection through a single row and alternatively through two staggered rows of holes onto a flat plate. The objective is to use an appropriate computational method for the simulation of the film cooling process in order to improve our understanding of the complex flow and heat transfer phenomena downstream of the coolant injection holes. A multi-grid and segmentation method is used to solve the transport equations of the film cooling process to achieve good local flow resolution and rapid convergence. The turbulence is represented by the k-ϵ model combined with a nonisotropic eddy-viscosity formulation and a near-wall k model. New experimental results are obtained for comparison with the numerical simulations. Cooling through single and double rows of orifices is investigated computationally; for the same overal mass injection, the double row cooling has better spanwise averaged film cooling effectiveness for the range of parameters investigated. The effects of mass flow ratios and injection angles on the double row cooling performance are investigated computationally. Comparison between the predicted and measured spanwise averaged effectiveness shows good agreement for mass flow ratios of 0.2 and 0.4 but also shows that the numerical values are consistently lower than the measured results for mass flow ratios of 0.8. This difference suggests that the k-ϵ turbulence model under-predicts the turbulence production resulting from the shear flow between the main stream and jets when the cross flow momentum is high and the associated streamwise vorticity is strong and therefore that the turbulence stresses and scalar fluxes are not correctly predicted in these cases. Some possible improvements are suggested.

Experimental Study of the Swirling Flow in the Volute of a Centrifugal Pump

1992 ◽  
Vol 114 (2) ◽  
pp. 366-372 ◽  
Author(s):  
T. Elholm ◽  
E. Ayder ◽  
R. Van den Braembussche
Keyword(s):  
Velocity Distribution ◽  
Mass Flow ◽  
Cross Sections ◽  
Swirling Flow ◽  
Three Dimensional ◽  
Pressure Rise ◽  
High Mass ◽  
Return Flow ◽  
Swirl Velocity ◽  
Low Mass

Detailed three-dimensional velocity distributions, corresponding to design and off-design operation, were measured in two different circumferential cross sections of a volute by means of LDV. It is shown that the swirl has a forced vortex type velocity distribution and that the location of the swirl center changes with mass flow. The throughflow velocity distribution is primarily defined by the conservation of angular momentum. A strong interaction between the throughflow and swirl velocity is observed. Flow visualization in the tongue region reveals a reversal of the velocity at the volute inlet with increasing mass flow. The pressure drop between volute outlet and inlet at low mass flow pushes extra fluid through the tongue gap and increases the mass flow in the volute. The abrupt pressure rise at high mass flow results in local return flow perturbing the flow in the outlet pipe.

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