Impact of Realistic Manufacturing Uncertainties on the Aerodynamic Performance of a Transonic Centrifugal Impeller

2020 ◽  
Author(s):  
Yiming Liu ◽  
Ruihong Qin ◽  
Yaping Ju ◽  
Stephen Spence ◽  
Chuhua Zhang
Keyword(s):  
Flow Field ◽  
Uncertainty Quantification ◽  
High Efficiency ◽  
Leading Edge ◽  
Skewed Distribution ◽  
Machining Process ◽  
High Dimensionality ◽  
Centrifugal Impeller ◽  
High Fidelity ◽  
Clear Understanding

Abstract Centrifugal impellers are inevitably subjected to manufacturing uncertainties during the machining process due to many factors. Such manufacturing uncertainties resulting in geometrical variations lead to impeller performance degradation. For a transonic impeller, the complexity of the flow field may amplify this deterioration. In view of this, it is important to have a clear understanding of the effect caused by manufacturing uncertainties. However, relevant studies are rare and lack consideration of realistic manufacturing uncertainties. Furthermore, the high dimensionality caused by high-fidelity uncertainty model makes the computational fluid dynamics (CFD) unaffordable, making the development of high-efficiency and high-fidelity method for high-dimensionality uncertainty quantification (UQ) problems become urgent. To tackle these limitations, a group of 92 machined centrifugal impellers were scanned, and a statistical model of realistic manufacturing uncertainties was built. With the combination of the CFD simulations and Non–Intrusive Polynomial Chaos (NIPC) methods, the influence of manufacturing uncertainties on the polytropic efficiency and flow field of a transonic centrifugal impeller was quantified. To achieve a good trade-off between the computational efficiency and accuracy for the UQ, a Dual Dimensionality Reduction (DDR) method was proposed, by which the dimensionality of the spatially varying input, i.e., the manufacturing error field, was reduced to 3. The results showed that the manufacturing errors of machined impellers follow Gaussian distributions with a mean error of zero and a shape increased standard deviation near the blade leading edge. The polytropic efficiency of the examined impeller exhibited a negatively skewed distribution and the mean efficiency was reduced by 0.34%. The flow mechanisms behind the performance degradations mainly lay in the increased shock losses near the blade tip and separation losses near the hub. The present study provides a fundamental contribution to the uncertainty quantification of turbomachinery and establishes a theoretical foundation for the development of robust centrifugal impellers.

Effects of Impeller Blade Loading on Industrial Centrifugal Compressor Performance and Stability

2010 ◽  
Author(s):  
Min Ji ◽  
Michael Cave ◽  
Donghui Zhang
Keyword(s):  
Flow Field ◽  
Energy Demand ◽  
Performance Test ◽  
High Efficiency ◽  
Oil And Gas Industry ◽  
Centrifugal Impeller ◽  
Experimental Investigations ◽  
Impeller Blade ◽  
Blade Loading ◽  
Compressor Performance

Multistage centrifugal compressors are widely used in the oil and gas industry for various applications. As energy demand increases, the compressor has been challenged to have both high efficiency and broad operating range in order to minimize the life-cycle operation cost. Therefore much effort has been devoted to improve performance of the centrifugal impeller through various design methods. This paper highlights experiences gained in the development of three-dimensional impeller design in an effort combining different design methodologies and experimental investigations. In the present paper, a radial impeller in a medium specific speed range was designed through the conventional direct approach as the baseline. Then, it was redesigned with a different loading profile and a challenged loading magnitude by means of the inverse design method. To assess the two design approaches, the resulting two impellers were manufactured and tested in a closed-loop compressor test rig. The experimental investigation consists of both the performance test and detailed traverse test measuring the flow field downstream of the impeller. The paper presents the comparison of impeller performance and time-averaged data of the downstream flow field between the two impellers. Analysis of the test data illustrates the critical impact of the blade loading on the overall compressor performance and stability.

Flow-Field-Assisted Dielectrophoretic Microchips for High-Efficiency Sheathless Particle/Cell Separation with Dual Mode

2021 ◽  
Author(s):  
Shitao Shen ◽  
Zichuan Yi ◽  
Xing Li ◽  
Shuting Xie ◽  
Mingliang Jin ◽  
...  
Keyword(s):  
Flow Field ◽  
Cell Separation ◽  
High Efficiency ◽  
Dual Mode

Numerical simulation of swirling flow effect on the first stage vane film cooling distribution

2016 ◽  
Vol 07 (03) ◽  
pp. 1650031
Author(s):  
Hong Yin
Keyword(s):  
Flow Field ◽  
Film Cooling ◽  
Swirling Flow ◽  
Cooling System ◽  
Leading Edge ◽  
Suction Side ◽  
Local Area ◽  
Swirl Flow ◽  
Flow Effect ◽  
Recirculation Flow

In advanced gas turbine technology, lean premixed combustion is an effective strategy to reduce peak temperature and thus, NO[Formula: see text] emissions. The swirler is adopted to establish recirculation flow zone, enhancing mixing and stabilizing the flame. Therefore, the swirling flow is dominant in the combustor flow field and has impact on the vane. This paper mainly investigates the swirling flow effect on the turbine first stage vane cooling system by conducting a group of numerical simulations. Firstly, the numerical methods of turbulence modeling using RANS and LES are compared. The computational model of one single swirl flow field is considered. Both the RANS and LES results give reasonable recirculation zone shape. When comparing the velocity distribution, the RANS results generally match the experimental data but fail to at some local area. The LES modeling gives better results and more detailed unsteady flow field. In the second step, the RANS modeling is incorporated to investigate the vane film cooling performance under the swirling inflow boundary condition. According to the numerical results, the leading edge film cooling is largely altered by the swirling flow, especially for the swirl core-leading edge aligned case. Compared to the pressure side, the suction side film cooling is more sensitive to the swirling flow. Locally, the film cooling jet is lifted and turned by the strong swirling flow.

Numerical Investigation of Intermittent Corner Separation in a Linear Compressor Cascade

2016 ◽  
Author(s):  
Wei Ma ◽  
Feng Gao ◽  
Xavier Ottavy ◽  
Lipeng Lu ◽  
A. J. Wang
Keyword(s):  
Flow Field ◽  
Large Scale ◽  
Leading Edge ◽  
Suction Side ◽  
Detached Eddy Simulation ◽  
Compressor Cascade ◽  
Linear Compressor ◽  
Corner Separation ◽  
Eddy Simulation ◽  
Linear Compressor Cascade

Recently bimodal phenomenon in corner separation has been found by Ma et al. (Experiments in Fluids, 2013, doi:10.1007/s00348-013-1546-y). Through detailed and accurate experimental results of the velocity flow field in a linear compressor cascade, they discovered two aperiodic modes exist in the corner separation of the compressor cascade. This phenomenon reflects the flow in corner separation is high intermittent, and large-scale coherent structures corresponding to two modes exist in the flow field of corner separation. However the generation mechanism of the bimodal phenomenon in corner separation is still unclear and thus needs to be studied further. In order to obtain instantaneous flow field with different unsteadiness and thus to analyse the mechanisms of bimodal phenomenon in corner separation, in this paper detached-eddy simulation (DES) is used to simulate the flow field in the linear compressor cascade where bimodal phenomenon has been found in previous experiment. DES in this paper successfully captures the bimodal phenomenon in the linear compressor cascade found in experiment, including the locations of bimodal points and the development of bimodal points along a line that normal to the blade suction side. We infer that the bimodal phenomenon in the corner separation is induced by the strong interaction between the following two facts. The first is the unsteady upstream flow nearby the leading edge whose angle and magnitude fluctuate simultaneously and significantly. The second is the high unsteady separation in the corner region.

scholarly journals Aerothermal Investigations of Mixing Flow Phenomena in Case of Radially Inclined Ejection Holes at the Leading Edge

1999 ◽  
Author(s):  
Dieter E. Bohn ◽  
Karsten A. Kusterer
Keyword(s):  
Flow Field ◽  
Secondary Flow ◽  
Gas Turbines ◽  
Leading Edge ◽  
Suction Side ◽  
Pressure Side ◽  
Blade Surface ◽  
Cooling Fluid ◽  
Flow Phenomena ◽  
Vortex Systems

A leading edge cooling configuration is investigated numerically by application of a 3-D conjugate fluid flow and heat transfer solver, CHT-Flow. The code has been developed at the Institute of Steam and Gas Turbines, Aachen University of Technology. It works on the basis of an implicit finite volume method combined with a multi-block technique. The cooling configuration is an axial turbine blade cascade with leading edge ejection through two rows of cooling holes. The rows are located in the vicinity of the stagnation line, one row is on the suction side, the other row is on the pressure side. The cooling holes have a radial ejection angle of 45°. This configuration has been investigated experimentally by other authors and the results have been documented as a test case for numerical calculations of ejection flow phenomena. The numerical domain includes the internal cooling fluid supply, the radially inclined holes and the complete external flow field of the turbine vane in a high resolution grid. Periodic boundary conditions have been used in the radial direction. Thus, end wall effects have been excluded. The numerical investigations focus on the aerothermal mixing process in the cooling jets and the impact on the temperature distribution on the blade surface. The radial ejection angles lead to a fully three dimensional and asymmetric jet flow field. Within a secondary flow analysis it can be shown that complex vortex systems are formed in the ejection holes and in the cooling fluid jets. The secondary flow fields include asymmetric kidney vortex systems with one dominating vortex on the back side of the jets. The numerical and experimental data show a good agreement concerning the vortex development. The phenomena on the suction side and the pressure side are principally the same. It can be found that the jets are barely touching the blade surface as the dominating vortex transports hot gas under the jets. Thus, the cooling efficiency is reduced.

New Development in High Efficiency Deep Grinding

2012 ◽  
Author(s):  
Andre D. L. Batako ◽  
Valery V. Kuzin ◽  
Brian Rowe
Keyword(s):  
Machine Tool ◽  
High Efficiency ◽  
Machining Process ◽  
Depth Of Cut ◽  
Removal Rates ◽  
Workpiece Surface ◽  
New Development ◽  
Cutting Processes ◽  
Selection Of ◽  
Made In

High Efficiency Deep Grinding (HEDG) has been known to secure high removal rates in grinding processes at high wheel speed, relatively large depth of cut and moderately high work speed. High removal rates in HEDG are associated with very efficient grinding and secure very low specific energy comparable to conventional cutting processes. Though there exist HEDG-enabled machine tools, the wide spread of HEDG has been very limited due to the requirement for the machine tool and process design to ensure workpiece surface integrity. HEDG is an aggressive machining process that requires an adequate selection of grinding parameters in order to be successful within a given machine tool and workpiece configuration. This paper presents progress made in the development of a specialised HEDG machine. Results of HEDG processes obtained from the designed machine tool are presented to illustrate achievable high specific removal rates. Specific grinding energies are shown alongside with measured contact arc temperatures. An enhanced single-pole thermocouple technique was used to measure the actual contact temperatures in deep cutting. The performance of conventional wheels is depicted together with the performance of a CBN wheel obtained from actual industrial tests.

A Laser-Doppler Investigation of the Flow inside a Backswept, Closed, Centrifugal Impeller

1979 ◽  
Vol 21 (1) ◽  
pp. 1-6 ◽  
Author(s):  
D. Adler ◽  
Y. Levy
Keyword(s):  
Flow Field ◽  
Flow Fields ◽  
Fundamental Difference ◽  
Laser Doppler ◽  
Centrifugal Impeller ◽  
Doppler Technique

A laser-Doppler technique is successfully applied to measure the flow field inside a closed, backswept impeller, through a rotating window. Results show that, in contrast to the flow in many radial-exit impellers, the flow in the backswept impeller is stable and attached. Further, comparison with an open impeller demonstrates the fundamental difference in the flow fields near the shroud.

Analysis of Transonic Bladerows With Non-Uniform Geometry Using Spectral Method

2020 ◽  
Author(s):  
Feng Wang ◽  
Luca di Mare
Keyword(s):  
Flow Field ◽  
Spectral Method ◽  
Computational Cost ◽  
Leading Edge ◽  
Wave Number ◽  
Efficient Tool ◽  
Flow Solver ◽  
Engine Order ◽  
Harmonic Flow ◽  
Good Agreement

Abstract Turbomachinery blade rows can have non-uniform geometries due to design intent, manufacture errors or wear. When predictions are sought for the effect of such non-uniformities, it is generally the case that whole assembly calculations are needed. A spectral method is used in this paper to approximate the flow fields of the whole assembly but with significantly less computation cost. The method projects the flow perturbations due to the geometry non-uniformity in an assembly in Fourier space, and only one passage is required to compute the flow perturbations corresponding to a certain wave-number of geometry variation. The performance of this method on transonic blade rows is demonstrated on a modern fan assembly. Low engine order and high engine order geometry non-uniformity (e.g. “saw-tooth” pattern) are examined. The non-linear coupling between the flow perturbations and the passage-averaged flow field is also demonstrated. Pressure variations on the blade surface and the potential flow field upstream of the leading edge from the proposed spectral method and the direct whole assembly solutions are compared. Good agreement is observed on both quasi-3D and full 3D cases. A lumped approach to compute deterministic fluxes is also proposed to further reduce the computational cost of the spectral method. The spectral method is formulated in such a way that it can be easily implemented into an existing harmonic flow solver by adding an extra source term, and can be potentially used as an efficient tool for aeromechanical and aeroacoustics design of turbomachinery blade rows.

Influence of different blade numbers on the performance of “saddle zone” in a mixed flow pump

2021 ◽  
pp. 095765092110460
Author(s):  
Leilei Ji ◽  
Wei Li ◽  
Weidong Shi ◽  
Fei Tian ◽  
Shuo Li ◽  
...  
Keyword(s):  
Flow Field ◽  
Leading Edge ◽  
Leakage Flow ◽  
Tip Leakage Flow ◽  
Mixed Flow ◽  
Impeller Blade ◽  
Flow Angle ◽  
Tip Leakage ◽  
Vorticity Transport ◽  
Flow Pump

In order to study the effect of different numbers of impeller blades on the performance of mixed-flow pump “saddle zone”, the external characteristic test and numerical simulation of mixed-flow pumps with three different impeller blade numbers were carried out. Based on high-precision numerical prediction, the internal flow field and tip leakage flow field of mixed flow pump under design conditions and stall conditions are investigated. By studying the vorticity transport in the stall flow field, the specific location of the high loss area inside the mixed flow pump impeller with different numbers of blades is located. The research results show that the increase in the number of impeller blades improve the pump head and efficiency under design conditions. Compared to the 4-blade impeller, the head and efficiency of the 5-blade impeller are increased by 5.4% and 21.9% respectively. However, the increase in the number of blades also leads to the widening of the “saddle area” of the mixed-flow pump, which leads to the early occurrence of stall and increases the instability of the mixed-flow pump. As the mixed-flow pump enters the stall condition, the inlet of the mixed-flow pump has a spiral swirl structure near the end wall for different blade numbers, but the depth and range of the swirling flow are different due to the change in the number of blades. At the same time, the change in the number of blades also makes the flow angle at 75% span change significantly, but the flow angle at 95% span is not much different because the tip leakage flow recirculates at the leading edge. Through the analysis of the vorticity transport results in the impeller with different numbers of blades, it is found that the reasons for the increase in the values of the vorticity transport in the stall condition are mainly impacted by the swirl flow at the impeller inlet, the tip leakage flow at the leading edge and the increased unsteady flow structures.

Flow Field and Hot Streak Migration Through a High Pressure Cooled Vanes With Representative Lean Burn Combustor Outflow

2018 ◽  
Vol 141 (4) ◽  
Author(s):  
Tommaso Bacci ◽  
Tommaso Lenzi ◽  
Alessio Picchi ◽  
Lorenzo Mazzei ◽  
Bruno Facchini
Keyword(s):  
Experimental Data ◽  
High Pressure ◽  
Flow Field ◽  
Fuel Injection ◽  
Leading Edge ◽  
Flame Stabilization ◽  
Lean Burn ◽  
Aero Engine ◽  
University Of Florence ◽  
Hot Streak

Modern lean burn aero-engine combustors make use of relevant swirl degrees for flame stabilization. Moreover, important temperature distortions are generated, in tangential and radial directions, due to discrete fuel injection and liner cooling flows respectively. At the same time, more efficient devices are employed for liner cooling and a less intense mixing with the mainstream occurs. As a result, aggressive swirl fields, high turbulence intensities, and strong hot streaks are achieved at the turbine inlet. In order to understand combustor-turbine flow field interactions, it is mandatory to collect reliable experimental data at representative flow conditions. While the separated effects of temperature, swirl, and turbulence on the first turbine stage have been widely investigated, reduced experimental data is available when it comes to consider all these factors together.In this perspective, an annular three-sector combustor simulator with fully cooled high pressure vanes has been designed and installed at the THT Lab of University of Florence. The test rig is equipped with three axial swirlers, effusion cooled liners, and six film cooled high pressure vanes passages, for a vortex-to-vane count ratio of 1:2. The relative clocking position between swirlers and vanes has been chosen in order to have the leading edge of the central NGV aligned with the central swirler. In order to generate representative conditions, a heated mainstream passes though the axial swirlers of the combustor simulator, while the effusion cooled liners are fed by air at ambient temperature. The resulting flow field exiting from the combustor simulator and approaching the cooled vane can be considered representative of a modern Lean Burn aero engine combustor with swirl angles above ±50 deg, turbulence intensities up to about 28% and maximum-to-minimum temperature ratio of about 1.25. With the final aim of investigating the hot streaks evolution through the cooled high pressure vane, the mean aerothermal field (temperature, pressure, and velocity fields) has been evaluated by means of a five-hole probe equipped with a thermocouple and traversed upstream and downstream of the NGV cascade.

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