Experimental and Numerical Verification of an Optimization of a Fast Rotating High-Performance Radial Compressor Impeller

2017 ◽  
Vol 139 (10) ◽  
Author(s):  
M. Elfert ◽  
A. Weber ◽  
D. Wittrock ◽  
A. Peters ◽  
C. Voss ◽  
...  
Keyword(s):  
High Performance ◽  
Pressure Ratio ◽  
Axial Compressor ◽  
Navier Stokes ◽  
Numerical Verification ◽  
Complex Flow ◽  
Radial Compressor ◽  
Wall Functions ◽  
Numerical Predictions ◽  
Compressor Design

An optimization has been performed on a well-proven radial compressor design known as the SRV4 impeller (the Krain impeller), which has been extensively tested in the past, using the autoopti tool developed at DLR's Institute of Propulsion Technology. This tool has shown its capability in several tasks, mainly for axial compressor and fan design as well as for turbine design. The optimization package autoopti was applied to the redesign and optimization of a radial compressor stage with a vaneless diffusor. This optimization was performed for the SRV4 compressor geometry without fillets using a relatively coarse structured mesh in combination with wall functions. The impeller geometry deduced by the optimization had to be slightly modified due to manufacturing constraints. In order to filter out the improvements of the new so-called SRV5 radial compressor design, two work packages were conducted: The first one was the manufacturing of the new impeller and its installation on a test rig to investigate the complex flow inside the machine. The aim was, first of all, the evaluation of a classical performance map and the efficiency chart achieved by the new compressor design. The efficiencies realized in the performance chart were enhanced by nearly 1.5%. A 5% higher maximum mass flow rate was measured in agreement with the Reynolds-averaged Navier–Stokes (RANS) simulations during the design process. The second work package comprises the computational fluid dynamics (CFD) analysis. The numerical investigations were conducted with the exact geometries of both the baseline SRV4 as well as the optimized SRV5 impeller including the exact fillet geometries. To enhance the prediction accuracy of pressure ratio and impeller efficiency, the geometries were discretized by high-resolution meshes of approximately 5 × 106 cells. For the blade walls as well as for the hub region, the mesh resolution allows a low-Reynolds approach in order to get high-quality results. The comparison of the numerical predictions and the experimental results shows a very good agreement and confirms the improvement of the compressor performance using the optimization tool autoopti.

Experimental and Numerical Verification of an Optimization of a Fast Rotating High Performance Radial Compressor Impeller

2016 ◽  
Author(s):  
M. Elfert ◽  
A. Weber ◽  
D. Wittrock ◽  
A. Peters ◽  
C. Voss ◽  
...  
Keyword(s):  
High Performance ◽  
Pressure Ratio ◽  
Axial Compressor ◽  
Numerical Verification ◽  
Complex Flow ◽  
Radial Compressor ◽  
Wall Functions ◽  
Numerical Predictions ◽  
Compressor Design ◽  
Compressor Impeller

Outgoing from a well-proven radial compressor design which has been extensively being tested in the past known as SRV4 impeller (Krain impeller), an optimization has been performed using the AutoOpti tool developed at DLR’s Institute of Propulsion Technology. This tool has shown its capability in several tasks, mainly for axial compressor and fan design as well as for turbine design. The optimization package AutoOpti was applied to the redesign and optimization of a radial compressor stage with a vaneless diffusor. The numerical results of this optimization were presented by Voss et al. [1] and by Raitor et al. [2]. The optimization was performed for the SRV4 compressor geometry without fillets using a relatively coarse structured mesh in combination with wall functions. The impeller geometry deduced by the optimization had to be slightly modified due to manufacturing constraints. In order to filter out the improvements of the new so-called SRV5 radial compressor design, two work packages were conducted: The first one was the manufacturing of the new impeller and its installation on a test rig to investigate the complex flow inside the machine. The aim was, first of all, the evaluation of a classical performance map and the efficiency chart achieved by the new compressor design. The efficiencies realized in the performance chart were enhanced by nearly 1.5 %. A 5 % higher maximum mass flow rate was measured in agreement with the RANS simulations during the design process. The second work package comprises the CFD analysis. The numerical investigations were conducted with the exact geometries of both, the baseline SRV4 as well as the optimized SRV5 impeller including the exact fillet geometries. To enhance the prediction accuracy of pressure ratio and impeller efficiency the geometries were discretized by high resolution meshes of approximately 5 million cells. For the blade walls as well as for the hub region the mesh resolution allows a low-Reynolds approach in order to get high quality results. The comparison of the numerical predictions and the experimental results shows a very good agreement and confirms the improvement of the compressor performance using the optimization tool AutoOpti.

A Deep Insight Into the Transonic Flow of an Advanced Centrifugal Compressor Design

2020 ◽  
Vol 142 (9) ◽  
Author(s):  
David Wittrock ◽  
Martin Junker ◽  
Manfred Beversdorff ◽  
Andreas Peters ◽  
Eberhard Nicke
Keyword(s):  
Centrifugal Compressor ◽  
Pressure Ratio ◽  
Three Dimensional ◽  
Leading Edge ◽  
Navier Stokes ◽  
Free Form ◽  
Numerical Verification ◽  
Deep Insight ◽  
Compressor Design ◽  
Design Speed

Abstract In the last decades, major improvements in transonic centrifugal compressor design have been achieved. The further exploration of design space is enabled by recent progress in structural mechanics and manufacturing. A challenging task of inducer design especially in terms of transonic inflow conditions is to provide a wide flow range and reduced losses due to a sufficient shock control. The use of so-called multidisciplinary design optimization with an extensive amount of free parameters leads finally to complex designs. DLR’s latest fast rotating centrifugal compressor (SRV5) operates at a design speed of Mu2 = 1.72 and a total pressure ratio of 5.72. This compressor design is characterized by an S-shaped leading edge and free-form blade surfaces. Due to the complex design, the key design features are difficult to explore. Therefore, nonintrusive measurements are conducted on the highly loaded SRV5. The laser-2-focus (L2F) approach that is used in addition with the doppler-global-velocimetry (DGV) delivers a three-dimensional velocity field. Besides the impeller inflow, the outflow is also part of the experimental and numerical verification of the advanced compressor design. Experimental results are compared with the numerical analysis of the compressor using DLR’s Reynolds-averaged Navier–Stokes Flow Solver TRACE. The deep insight of the inflow leads to a better understanding of the operating behavior of such impeller designs.

scholarly journals Comparison of Heat Transfer Measurements With Computations for Turbulent Flow Around a 180 Degree Bend

1991 ◽  
Author(s):  
D. L. Besserman ◽  
S. Tanrikut
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Turbulent Flow ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Navier Stokes ◽  
Complex Flow ◽  
Wall Functions ◽  
Numerical Predictions ◽  
Fully Developed Turbulent Flow

Results of detailed heat transfer measurements are presented for all four walls of a 180° 1:1 aspect ratio duct. Experiments using a transient heat transfer technique with liquid crystal thermography were conducted for turbulent flow over a Reynolds numbers range of 12,500–50,000. Computational results using a Navier-Stokes code are also presented to complement the experiments. Two near-wall shear-stress treatments (wall functions and the two layer wall integration method) were evaluated in conjunction with k-ε formulation of turbulence to assess their ability to predict high local gradients in heat transfer. Results showed that heat transfer on the convex and concave walls is a manifestation of the complex flow field created by the 180° bend. For the flat walls, the streamwise average Nusselt number increases to approximately two times the fully developed turbulent flow value. Ninety degrees into the bend, the importance of the cross-stream gradients is evident with the Nusselt number varying from approximately one to three times the fully developed turbulent flow value. The numerical predictions with two-layer wall integration k-ε turbulence model show very good agreement with the experimental data. These results reinforce the need to accurately predict local heat transfer rates in cooling passages of advanced turbine airfoils to enhance the durability of these components.

Comparison of Heat Transfer Measurements With Computations for Turbulent Flow Around a 180 deg Bend

1992 ◽  
Vol 114 (4) ◽  
pp. 865-871 ◽  
Author(s):  
D. L. Besserman ◽  
S. Tanrikut
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Turbulent Flow ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Navier Stokes ◽  
Complex Flow ◽  
Wall Functions ◽  
Numerical Predictions ◽  
Fully Developed Turbulent Flow

Results of detailed heat transfer measurements are presented for all four walls of a 180 deg 1:1 aspect ratio duct. Experiments using a transient heat transfer technique with liquid crystal thermography were conducted for turbulent flow over a Reynolds numbers range of 12,500–50,000. Computational results using a Navier–Stokes code are also presented to complement the experiments. Two near-wall shear-stress treatments (wall functions and the two layer wall integration method) were evaluated in conjunction with k–ε formulation of turbulence to assess their ability to predict high local gradients in heat transfer. Results showed that heat transfer on the convex and concave walls is a manifestation of the complex flow field created by the 180 deg bend. For the flat walls, the streamwise average Nusselt number increases to approximately two times the fully developed turbulent flow value. Ninety degrees into the bend, the importance of the cross-stream gradients is evident with the Nusselt number varying from approximately one to three times the fully developed turbulent flow value. The numerical predictions with two-layer wall integration k–ε turbulence model show very good agreement with the experimental data. These results reinforce the need to predict local heat transfer rates accurately in cooling passages of advanced turbine airfoils to enhance the durability of these components.

Flow Characteristics of a Novel Centrifugal Compressor Design

2016 ◽  
Author(s):  
Shashank Mishra ◽  
Shaaban Abdallah ◽  
Mark Turner
Keyword(s):  
Centrifugal Compressor ◽  
Pressure Ratio ◽  
Flow Characteristics ◽  
Axial Compressor ◽  
Low Pressure ◽  
Flow Path ◽  
Optimization Techniques ◽  
Single Stage ◽  
Multi Stage ◽  
Compressor Design

Multistage axial compressor has an advantage of lower stage loading as compared to a single stage. Several stages with low pressure ratio are linked together which allows for multiplication of pressure to generate high pressure ratio in an axial compressor. Since each stage has low pressure ratio they operate at a higher efficiency and the efficiency of multi-stage axial compressor as a whole is very high. Although, single stage centrifugal compressor has higher pressure ratio compared with an axial compressor but multistage centrifugal compressors are not as efficient because the flow has to be turned from radial at outlet to axial at inlet for each stage. The present study explores the advantages of extending the axial compressor efficient flow path that consist of rotor stator stages to the centrifugal compressor stage. In this invention, two rotating rows of blades are mounted on the same impeller disk, separated by a stator blade row attached to the casing. A certain amount of turning can be achieved through a single stage centrifugal compressor before flow starts separating, thus dividing it into multiple stages would be advantageous as it would allow for more flow turning. Also the individual stage now operate with low pressure ratio and high efficiency resulting into an overall increase in pressure ratio and efficiency. The baseline is derived from the NASA low speed centrifugal compressor design which is a 55 degree backward swept impeller. Flow characteristics of the novel multistage design are compared with a single stage centrifugal compressor. The flow path of the baseline and multi-stage compressor are created using 3DBGB tool and DAKOTA is used to optimize the performance of baseline as well novel design. The optimization techniques used are Genetic algorithm followed by Numerical Gradient method. The optimization resulted into improvements in incidence and geometry which significantly improved the performance over baseline compressor design. The multistage compressor is more efficient with a higher pressure ratio compared with the base line design for the same work input and initial conditions.

Design and Test of a Novel Highly-Loaded Compressor

2019 ◽  
Author(s):  
Chengwu Yang ◽  
Ge Han ◽  
Shengfeng Zhao ◽  
Xingen Lu ◽  
Yanfeng Zhang ◽  
...  
Keyword(s):  
Pressure Ratio ◽  
Axial Compressor ◽  
Pressure Rise ◽  
Tip Clearance ◽  
Leakage Flow ◽  
Flow Angle ◽  
Stall Margin ◽  
High Pressure Ratio ◽  
Numerical Predictions ◽  
Highly Loaded

Abstract The blades of rear stages in small size core compressors are reduced to shorter than 20 mm or even less due to overall high pressure ratio. The growing of tip clearance-to-blade height ratio of the rear stages enhance the leakage flow and increase the possibility of a strong clearance sensitivity, thus limiting the compressor efficiency and stability. A new concept of compressor, namely diffuser passage compressor (DP), for small size core compressors was introduced. The design aims at making the compressors robust to tip clearance leakage flow by reducing pressure difference between pressure and suction surfaces. To validate the concept, the second stage of a two-stage highly loaded axial compressor was designed with DP rotor according to a diffuser map. The diffuser passage stage has the same inlet condition and loading as the conventional compressor (CNV) stage, of which the work coefficient is around 0.37. The predicted performance and flow field of the DP were compared with the conventional axial compressor in detail. The rig testing was supplemented with the numerical predictions. Results reveal that the throttle characteristic of DP indicates higher pressure rise and the loss reduction in tip clearance is mainly responsible for the performance improvement. For the compressor with DP, the pressure and flow angle are more uniform on exit plane. What’s more, the rotor with diffused passage reveals more robust than the conventional rotor at double clearance gap. Furthermore, the experimental data indicate that DP presents higher pressure rise at design and part speeds. At design speed, the stall margin was extended by 7.25%. Moreover, peak adiabatic efficiency of DP is also higher than that of CNV by about 0.7%.

Using Optimization in Industrial Multi-Point Radial Compressor Design: Map Correction

2019 ◽  
Author(s):  
Edward P. Childs ◽  
Dimitri Deserranno ◽  
Akshay Bagi
Keyword(s):  
Mass Flow ◽  
Static Pressure ◽  
Pressure Ratio ◽  
Base Case ◽  
Design Specification ◽  
Radial Compressor ◽  
Surrogate Based Optimization ◽  
Compressor Design ◽  
Mass Flow Rates ◽  
Operating Points

Abstract The application of Surrogate-Based Optimization (SBO) to the industrial design process for a radial compressor with two operating points is described. The design specification includes two operating points at mass flow rates differing by a factor of three, and efficiency and pressure ratio targets for each point. The base case, while roughly sized from 1D analysis, fails to achieve the pressure ratio targets. In this paper, the optimization focusses on correcting the two speed-line map of total to static pressure ratio vs. mass flow rate. “Smart parameterization”, combining independent and dependent geometric parameters, and yielding reasonable geometries for most input combinations, coupled with efficient SBO, with separate models for response surface modeling and failure prediction, yields a design achieving the targets in just 57 CFD runs. FINE/Turbo [1] is used as the CFD analysis code and FINE/Design3D [2] and MINAMO [3] as the multi-objective optimizer.

scholarly journals Numerical Optimization of a Stall Margin Enhancing Recirculation Channel for an Axial Compressor

Fluids ◽  
2019 ◽  
Vol 4 (2) ◽  
pp. 88
Author(s):  
Motoyuki Kawase ◽  
Aldo Rona
Keyword(s):  
High Speed ◽  
High Performance ◽  
Fluid Dynamic ◽  
Axial Compressor ◽  
Leading Edge ◽  
Navier Stokes ◽  
Test Case ◽  
Dynamic Simulations ◽  
Stall Margin ◽  
Casing Treatment

A proof of concept is provided by computational fluid dynamic simulations of a new recirculating type casing treatment. This treatment aims at extending the stable operating range of highly loaded axial compressors, so to improve the safety of sorties of high-speed, high-performance aircraft powered by high specific thrust engines. This casing treatment, featuring an axisymmetric recirculation channel, is evaluated on the NASA rotor 37 test case by steady and unsteady Reynolds Averaged Navier Stokes (RANS) simulations, using the realizable k-ε model. Flow blockage at the recirculation channel outlet was mitigated by chamfering the exit of the recirculation channel inner wall. The channel axial location from the rotor blade tip leading edge was optimized parametrically over the range −4.6% to 47.6% of the rotor tip axial chord c z . Locating the channel at 18.2% c z provided the best stall margin gain of approximately 5.5% compared to the untreated rotor. No rotor adiabatic efficiency was lost by the application of this casing treatment. The investigation into the flow structure with the recirculating channel gave a good insight into how the new casing treatment generates this benefit. The combination of stall margin gain at no rotor adiabatic efficiency loss makes this design attractive for applications to high-speed gas turbine engines.

Vorticity Dynamics in Axial Compressor Flow Diagnosis and Design

2008 ◽  
Vol 130 (4) ◽  
Author(s):  
Yantao Yang ◽  
Hong Wu ◽  
Qiushi Li ◽  
Sheng Zhou ◽  
Jiezhi Wu
Keyword(s):  
Pressure Ratio ◽  
Axial Compressor ◽  
Design Procedure ◽  
Abel Equation ◽  
Navier Stokes ◽  
Design Stage ◽  
Analysis And Design ◽  
Compressor Performance ◽  
Performance Check ◽  
Integrated Performance

It is well recognized that vorticity and vortical structures appear inevitably in viscous compressor flows and have strong influence on the compressor performance. However, conventional analysis and design procedure cannot pinpoint the quantitative contribution of each individual vortical structure to the integrated performance of a compressor, such as the stagnation-pressure ratio and efficiency. We fill this gap by using the so-called derivative-moment transformation, which has been successfully applied to external aerodynamics. We show that the compressor performance is mainly controlled by the radial distribution of azimuthal vorticity, of which an optimization in the through-flow design stage leads to a simple Abel equation of the second kind. The satisfaction of the equation yields desired circulation distribution that optimizes the blade geometry. The advantage of this new procedure is demonstrated by numerical examples, including the posterior performance check by 3D Navier–Stokes simulation.

scholarly journals Flow behavior in a contra-rotating transonic axial compressor

2021 ◽  
Vol 15 (3) ◽  
pp. 8440-8449
Author(s):  
Sarallah Abbasi ◽  
Maryam Alizadeh
Keyword(s):  
Flow Behavior ◽  
Pressure Ratio ◽  
Flow Analysis ◽  
Three Dimensional ◽  
Axial Compressor ◽  
Navier Stokes ◽  
Tip Leakage Flow ◽  
Ansys Cfx ◽  
Energy Equations ◽  
Compressor Efficiency

This study investigated a three-dimensional flow analysis on a two-stage contra-rotating axial compressor using the Navier–Stokes, continuity, and energy equations with Ansys CFX commercial software. In order to validate the obtained results, the absolute and relative flow angles curves for each rotor in radial direction were extracted and compared with the other investigation results, indicating good agreement. The compressor efficiency curve also was extracted by varying the compressor pressure ratio and compressor efficiency against mass flow rate. The flow results revealed that further distortion of the flow structure in the second rotor imposed a greater increase in the amount of entropy, especially at near-stall conditions. The increase of entropy in the second rotor is due to the interference of the tip leakage flow with the main flow which consequently caused more drops in the second rotor, suggesting that more efficacy of flow control methods occurred in the second rotor than in the first rotor.

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