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.

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.

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.

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

2019 ◽  
Author(s):  
D. Wittrock ◽  
M. Junker ◽  
M. Beversdorff ◽  
A. Peters ◽  
E. Nicke
Keyword(s):  
Centrifugal Compressor ◽  
Pressure Ratio ◽  
Three Dimensional ◽  
Leading Edge ◽  
Free Form ◽  
Numerical Verification ◽  
Deep Insight ◽  
Flow Solver ◽  
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, non-intrusive 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 ouflow 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 RANS Flow Solver TRACE. The deep insight of the inflow leads to a better understanding of the operating behavior of such impeller designs.

Instantaneous Measurements in the Jet-Wake Discharge Flow of a Centrifugal Compressor Impeller

1975 ◽  
Vol 97 (3) ◽  
pp. 337-345 ◽  
Author(s):  
D. Eckardt
Keyword(s):  
Centrifugal Compressor ◽  
Pressure Ratio ◽  
Theoretical Models ◽  
Vaneless Diffuser ◽  
Impeller Blade ◽  
Measuring Systems ◽  
Compressor Design ◽  
Wake Patterns ◽  
Compressor Impeller ◽  
Critical Problems

One of the critical problems in centrifugal compressor design is the diffuser-impeller interaction. Up to now, theoretical models, which describe one of the salient features of this problem, the impeller discharge mixing process, appear to be proved experimentally only at low tip speeds. In the present study investigations on this subject were accomplished in the vaneless diffuser of a low-pressure ratio centrifugal compressor, running at tip speeds of 300 m/s. Detailed, instantaneous measurements in the impeller discharge mixing zone were performed by high-frequency measuring systems. Relative velocity distributions at the exit of impeller blade channels show pronounced jet/wake-patterns. The radial extension of flow distortions in the vaneless diffuser entry region, caused by rotating wakes, reached up to higher radius ratios than predicted by theoretical models.

Multi Stage Axial Compressor Design and Performance Evaluation

2011 ◽  
Author(s):  
Young Seok Kang ◽  
Tae Choon Park ◽  
Oh Sik Hwang ◽  
Soo Seok Yang
Keyword(s):  
Performance Test ◽  
Pressure Ratio ◽  
Three Dimensional ◽  
Axial Compressor ◽  
Pressure Rise ◽  
Multi Stage ◽  
Compressor Design ◽  
Test Result ◽  
Highly Loaded ◽  
Small Aircraft

Recently, needs for Unmanned Air Vehicle (UAV) and small aircraft are increasing and demands for small turbo jet or turbo fan engines are also increasing. Then, size and weight are the two main restrictions in UAV or small aircraft propulsion system applications. One method for resolving such a problem is to increase the pressure rise per stage and to reduce the number of stages. Nowadays, matured compressor aerodynamic design techniques enable us to design highly loaded axial compressors. This paper covers from the design step of a highly loaded transonic axial compressor to the performance test result and its analysis. At the fore part of the paper, aerodynamic process of a multi stage axial compressor is introduced. To satisfy both of the mass flow and pressure rise, the compressor should rotate at a high rotational speed. Therefore the transonic flow field forms in the rotor stages and it is designed with a relatively high pressure rise per stage to satisfy its design target. Basically, one dimensional and quasi three dimensional compressor design were carried with compressor design codes. The compressor stage consists of 3 stages, and the bulk pressure ratio is 2.5. The first stage is burdened with the highest pressure ratio and less pressure rises occur in the following stages. Also it is designed that tip Mach number of the first rotor row does not exceed 1.3. The final design was confirmed by iterating three dimensional CFD calculations to satisfy design target and some design intentions. In the latter part of the paper, its performance test processes are briefly introduced. The performance test result showed that the overall compressor performance targets; pressure ratio and efficiency are well achieved. From the test results, we found some clues for further improvement and optimization of the compressor aerodynamic performance.

Development of Method and Computer Program for Multistage Axial Compressor Design: Part I — Mean Line Design and Example Cases

2018 ◽  
Author(s):  
Milan Banjac ◽  
Milan V. Petrovic
Keyword(s):  
Computer Program ◽  
Pressure Ratio ◽  
Axial Compressor ◽  
Flow Coefficient ◽  
Future Research ◽  
Compressor Design ◽  
Multistage Compressor ◽  
The Stability ◽  
Automated Optimization ◽  
Line Design

An axial compressor loss and deviation model that was developed and presented during previous research has now been used to develop a computer program for multistage compressor design. A set of input data including overall parameters such as pressure ratio and mass flow rate and the first-stage parameters such as inlet flow coefficient and rotor tip Mach number are used to determine a number of stages and their geometry, speed and relevant flow properties. Then a subsequent redistribution of parameters for separate stages can be carried out in order to increase the stability indicators and efficiency over a desired operating range. A selected stage vortex law determines velocity triangles and blading geometry for hub and tip sections, which allows the generation of a realistic flow path shape. The developed program is considered to be a flexible and stable tool useful for tasks of manual or automated optimization when combined with an external optimization algorithm. This paper presents a basic mathematical model and the level of accuracy achieved. This is demonstrated through examples of manual design and redesign cases, while automated optimization will be included in future research.

Supersonic Compression Stage Design and Test Results

2004 ◽  
Author(s):  
Shawn P. Lawlor ◽  
John B. Hinkey ◽  
Steven G. Mackin ◽  
Scott Henderson ◽  
Jonathan Bucher ◽  
...  
Keyword(s):  
Power Systems ◽  
High Performance ◽  
High Efficiency ◽  
Pressure Ratio ◽  
Test Results ◽  
Stage Design ◽  
Concept System ◽  
Operational Characteristics ◽  
Compressor Design ◽  
Machinery Design

Ramgen Power Systems, Inc. (RPS) is developing a family of high performance supersonic compressors that combine many of the aspects of shock compression systems commonly used in supersonic flight inlet design with turbo-machinery design practices employed in conventional axial and centrifugal compressor design. The result is a high efficiency compressor that is capable of single stage pressure ratios in excess of those available in existing axial or centrifugal compressors. A variety of design configurations for land-based compressors utilizing this system have been explored. A proof-of-concept system has been designed to demonstrate the basic operational characteristics of this family of compressors when operating on air. The test unit was designed to process ~1.43 kg/s and produce a pressure ratio across the supersonic rotor of 2.25:1. The theory of operation of this system will be reviewed along with selected results from initial performance tests.

Measured and Predicted Performance of a High Pressure Ratio Supersonic Compressor Rotor

2008 ◽  
Author(s):  
Allan D. Grosvenor ◽  
David A. Taylor ◽  
Jonathan R. Bucher ◽  
Michael J. Aarnio ◽  
Paul M. Brown ◽  
...  
Keyword(s):  
Boundary Layer ◽  
High Pressure ◽  
Carbon Capture ◽  
Pressure Ratio ◽  
Axial Compressor ◽  
Compression System ◽  
High Pressure Ratio ◽  
Compressor Rotor ◽  
Numerical Predictions ◽  
Shock System

The testing of an 8:1 pressure ratio supersonic single axial compressor rotor referred to as Rampressor-2 is described. Design of this shockwave compression system is based on principles employed for supersonic intakes consisting of a multi-shock compression system and boundary layer treatment. The rotor consists of three blade passages within which the shock system is produced by a ramp, throat and diffuser contoured on the hub. The technology has been previously demonstrated in a 2.3:1 pressure ratio experimental test compressor (Rampressor-1). Measured performance is compared with numerical predictions. Further developments to improve Rampressor performance are discussed, and the appropriateness of this technology for Carbon Capture & Sequestration and LNG applications is highlighted.

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