Experimental Investigation on Double Anti-Stall Ring Effects on Reversible Ventilation Fan Performance

2016 ◽  
Author(s):  
Alessandro Corsini ◽  
Giovanni Delibra ◽  
Anthony G. Sheard ◽  
David Volponi
Keyword(s):  
Operating Conditions ◽  
Axial Position ◽  
Axial Fan ◽  
Crucial Issue ◽  
Stall Margin ◽  
Abrupt Changes ◽  
Stall Margin Improvement ◽  
Design Selection ◽  
Inlet Conditions ◽  
Casing Treatments

Stall margin improvement is a crucial issue during fan design, selection and installation. In fact, several industrial fans are operated in extreme applications and requested to be highly flexible in order to be able to withstand abrupt changes in operating conditions. This is the case of fans operated under distorted inlet conditions or interacting with other fans or used for reversible operations in tunnel and metro applications. This paper reports on a systematic experimental study on the effects of the use of casing treatments on the performance of a single stage, reversible, axial fan. Tests focused on the performance of up-stream single treatment and up- and downstream double treatment, respectively designed to prevent the fan to run into stall in forward-only operations and forward- and reverse- operations. The study reports on the assessment of the change in performance, in normal and stalled operations, with an emphasis on the relative axial position between casing treatments and the impeller blades. The analysis demonstrates the achievement of significant improvements in performance in the unstable region for all the tested configurations with marginal losses in the stable counter-part.

Influencing Parameters of Tip Blowing Interacting With Rotor Tip Flow

2016 ◽  
Vol 139 (2) ◽  
Author(s):  
Cyril Guinet ◽  
André Inzenhofer ◽  
Volker Gümmer
Keyword(s):  
Geometric Model ◽  
Axial Compressor ◽  
Axial Flow ◽  
Navier Stokes ◽  
Axial Position ◽  
Design Parameters ◽  
Stall Margin ◽  
Casing Treatment ◽  
Transonic Compressor ◽  
Casing Treatments

The design space of axial-flow compressors is restricted by stability issues. Different axial-type casing treatments (CTs) have shown their ability to enhance compressor stability and to influence efficiency. Casing treatments have proven to be effective, but there still is need for more detailed investigations and gain of understanding for the underlying flow mechanism. Casing treatments are known to have a multitude of effects on the near-casing 3D flow field. For transonic compressor rotors, these are more complex, as super- and subsonic flow regions alternate while interacting with the casing treatment. To derive design rules, it is important to quantify the influence of the casing treatment on the different tip flow phenomena. Designing a casing treatment in a way that it antagonizes only the deteriorating secondary flow effects can be seen as a method to enhance stability while increasing efficiency. The numerical studies are carried out on a tip-critical rotor of a 1.5-stage transonic axial compressor. The examined recirculating tip blowing casing treatment (TBCT) consists of a recirculating channel with an air off-take above the rotor and an injection nozzle in front of the rotor. The design and functioning of the casing treatment are influenced by various parameters. A variation of the geometry of the tip blowing, more specifically the nozzle aspect ratio, the axial position, or the tangential orientation of the injection port, was carried out to identify key levers. The tip blowing casing treatment is defined as a parameterized geometric model and is automatically meshed. A sensitivity analysis of the respective design parameters of the tip blowing is carried out on a single rotor row. Their impact on overall efficiency and their ability to improve stall margin are evaluated. The study is carried out using unsteady Reynolds-averaged Navier–Stokes (URANS) simulations.

scholarly journals Flow mechanism of affecting an axial flow compressor performance and stability with cross-blade slot casing treatments

2018 ◽  
Vol 233 (1) ◽  
pp. 17-36 ◽  
Author(s):  
HaoGuang Zhang ◽  
XuDong Zhang ◽  
YanHui Wu ◽  
WuLi Chu ◽  
HaiYang Kuang
Keyword(s):  
Axial Flow ◽  
Low Energy ◽  
Peak Efficiency ◽  
Stall Margin ◽  
Casing Treatment ◽  
Flow Loss ◽  
Stall Margin Improvement ◽  
And Performance ◽  
Flow Compressor ◽  
Casing Treatments

The objective of this study is to evaluate the effect of cross-blade slot casing treatment on the stability and performance of an axial flow compressor rotor. The experimental and unsteady calculated results both show that cross-blade slot casing treatment can generate about 22% stall margin improvement, and the compressor peak efficiency is reduced by about 13%. The detailed flow-field analyses indicate that the sucked and injected flow caused by the slots of cross-blade slot casing treatment can restrain the rotor tip passage blockage, which is made by the low energy tip clearance leakage vortex. When cross-blade slot casing treatment is applied, not only the rotor wheel flange work becomes lower in most of the rotor blade span, but also the flow loss in the blade tip passage becomes fairly large due to the strong interaction between the mainstream and the injected flows made by the slots. As a result, the compressor total pressure ratio and efficiency for cross-blade slot casing treatment are reduced obviously. Three kinds of new cross-blade slot casing treatment were designed according to the previous successful experience and investigated in this paper. The numerical results show that the new three cross-blade slot casing treatments both generate about 54% stall margin improvement at the cost of minor peak efficiency. For one new cross-blade slot casing treatment (CSCT2), the compressor peak efficiency is reduced by about 0.3%. The low energy TLV, which is present for cross-blade slot casing treatment, is removed by the strong sucked flow made by CSCT2. Moreover, the interaction between the mainstream and the injected flows caused by CSCT2 becomes weak obviously, and the corresponding flow loss is reduced greatly. Hence, the compressor stability and performance with CSCT2 are higher than those with cross-blade slot casing treatment.

Understanding the Flow Behavior in a Low Hub-Tip Ratio, High Aspect Ratio Contra-Rotating Axial Fan Stage

2012 ◽  
Author(s):  
Chetan S. Mistry ◽  
A. M. Pradeep
Keyword(s):  
Aspect Ratio ◽  
Total Pressure ◽  
Numerical Study ◽  
Flow Behavior ◽  
Experimental Studies ◽  
Pressure Rise ◽  
Operating Conditions ◽  
Speed Ratio ◽  
Axial Fan ◽  
Stall Margin

This paper discusses the results of a parametric study of a pair of contra-rotating axial fan rotors. The rotors were designed to deliver a mass flow of 6 kg/s at 2400 rpm. The blades were designed with a low hub-tip ratio of 0.35 and an aspect ratio of 3.0. Numerical and experimental studies were carried out on these contra-rotating rotors operating at a Reynolds number of 1.25 × 105 (based on blade chord). The axial spacing between the rotors was varied between 50 to 120 % of the chord of rotor 1. The performance of the rotors was evaluated at each of these spacing at design and off-design speeds. The results from the numerical study (using ANSYS CFX) were validated using experimental data. In spite of certain limitations of CFD under certain operating conditions, it was observed that the results agreed well with those from the experiments. The performance of the fan was evaluated based on the variations of total pressure, velocity components and flow angles at design and off-design operating conditions. The measurement of total pressure, flow angles etc. are taken upstream of the first rotor, between the two rotors and downstream of the second rotor. It was observed that the aerodynamics of the flow through a contra rotating stage is significantly influenced by the axial spacing between the rotors and the speed ratio of the rotors. With increasing speed ratios, the strong suction generated by the second rotor, improves the stage pressure rise and the stall margin. Lower axial spacing on the other hand, changes the flow incidence to the second rotor and thereby improves the overall performance of the stage. The performance is investigated at different speed ratios of the rotors at varying axial spacing.

Stall Margin Improvement by Use of Casing Treatments

2013 ◽  
Author(s):  
Christian T. Pixberg ◽  
Heinz-Peter Schiffer ◽  
M. H. Ross ◽  
J. D. Cameron ◽  
S. C. Morris
Keyword(s):  
Tip Clearance ◽  
Stall Margin ◽  
Tip Clearance Flow ◽  
Casing Treatment ◽  
Transonic Compressor ◽  
Clearance Flow ◽  
Beneficial Impact ◽  
Stall Margin Improvement ◽  
Blade Tip ◽  
Casing Treatments

The beneficial impact of casing treatments on the stall margin of tip-critical compressors has been proven many times. However, there is still no simple and general method to predict their actual effectiveness. The present work considers the axial velocity deficit that is generally observed at the blade tip. This so called tip-blockage is caused by the tip clearance flow. That is investigated for different configurations of the transonic compressor test facilities in Darmstadt and Notre Dame and the results are presented in this paper. Similar circumferential groove casing treatments were applied to different single-stage and 1.5-stage compressors. They all had a tip critical behavior in common, but exhibited different design philosophies. The effectiveness of similar casing treatments on different stages was observed. A new method for calculating tip-blockage is introduced based on compressor performance and the results of a through-flow tool. A direct link between blockage growth and stall margin improvement was found for circumferential grooves casing treatments. Additionally, the results of an axial slot casing treatment are taken into account.

Effect of Novel Casing Treatment on the Suppression of Stall Precursor in a Transonic Compressor

2014 ◽  
Author(s):  
Dakun Sun ◽  
Xiaofeng Sun ◽  
Xiaohua Liu ◽  
Feng Lin ◽  
Nie Chao Qun
Keyword(s):  
Perforated Plate ◽  
Area Ratio ◽  
Open Area ◽  
Stall Inception ◽  
Stall Margin ◽  
Casing Treatment ◽  
Transonic Compressor ◽  
Stall Margin Improvement ◽  
Stall Precursor ◽  
Casing Treatments

A kind of novel casing treatment is proposed to realize stall margin enhancement by suppressing stall precursor in turbomachinery. In view of its different configuration and mechanism, such casing treatment is named as stall precursor-suppressed casing treatment in the present work, or SPS casing treatment for short. In the present work, the experiments of SPS casing treatment are conducted in a transonic compressor J69 Rotor/Stage. The SPS casing treatment which consists of a backchamber and a perforated plate is designed according to a proposed theoretical model. It is noted that the open area ratio of the casing treatment is only 4–12%, which is much smaller than traditional casing treatments with over 50% open area ratio. The tests show that the SPS casing treatment can improve the stall margin by 8–12% for J69 Rotor, and 4–12% for J69 Stage. Meanwhile, the mechanism of stall margin improvement with such casing treatment will be revealed in this investigation. Comparing with the evolution of the precursors without casing treatments, the propagation of the stall inception waves will be suppressed and the non-linear development of the stall process will be delayed under the casing treatment case.

Computational Analysis of Passive Stall Delay Through Vaned Recess Treatment

2001 ◽  
Author(s):  
A. Ghila ◽  
A. Tourlidakis
Keyword(s):  
Axial Flow ◽  
Pressure Rise ◽  
Navier Stokes ◽  
Working Mechanism ◽  
Significant Drop ◽  
Stall Margin ◽  
Casing Treatment ◽  
Work Input ◽  
Stall Margin Improvement ◽  
Casing Treatments

This paper presents a computational investigation of flows in a single axial flow fan with and without casing treatment. It analyses the effect of the recess casing treatment on stall margin improvement as well as its influence on global performance parameters. The paper seeks to offer a contribution to the understanding of the physical processes occurring when approaching stall and the working mechanism by which casing treatments improve stall margin. A Reynolds-Averaged Navier-Stokes CFD code was used for the analysis and the numerical investigation of the overall performance, efficiency and work-input characteristics of the fan were found to agree very well with previously reported experimental results. The effect of casing treatment was investigated using two types of configurations, vaneless and vaned casing. The vaneless casing treatment produced a sizeable stall margin improvement with negligible loss of efficiency. The recess was fitted later with vanes and was shown to offer both a further stall margin improvement and an increase in the pressure rise coefficient without any significant drop in efficiency at design conditions.

Parametric Study for Lossless Casing Treatment on a Mixed-Flow Compressor Rotor

2015 ◽  
Author(s):  
Noureddine Djeghri ◽  
Huu Duc Vo ◽  
Hong Yu
Keyword(s):  
Parametric Study ◽  
Numerical Study ◽  
Axial Position ◽  
Design Parameters ◽  
Skew Angle ◽  
Peak Efficiency ◽  
Mixed Flow ◽  
Stall Margin ◽  
Casing Treatment ◽  
Stall Margin Improvement

A systematic numerical study has been carried out to investigate the effects of casing treatment slots geometry and location on the stall margin and peak efficiency of an isolated mixed-flow rotor at high subsonic flow conditions. Based on the literature review for axial rotor, a semi-circular axial skewed slot casing treatment placed in the leading edge region was chosen as the starting configuration as it has the best potential of producing stall margin improvement with low peak efficiency loss. A computational parametric study was performed from this baseline casing treatment geometry to identify the most important geometrical design parameters and to arrive at a design with noticeable stall margin improvement and no loss in peak efficiency. The results show that the design parameters with the largest impact on stall margin improvement and peak efficiency are: open area ratio, slot skew angle, slot axial length and slot axial position. The slots depth and slot shape seem to have only limited influence on performance. While not yet optimized, a slot casing treatment design with significant stall margin improvement and no loss in peak efficiency was obtained. To the authors’ knowledge, this work is the most extensive slot casing treatments parametric study so far in term of number of design parameters considered.

The Design, Selection, and Application of Reciprocating Compressors for Fuel Gas Service

1995 ◽  
Vol 117 (1) ◽  
pp. 88-93
Author(s):  
D. Hough
Keyword(s):  
Power Generation ◽  
Control Systems ◽  
Operating Cost ◽  
Operating Conditions ◽  
Modular Approach ◽  
Reciprocating Compressor ◽  
Fuel Gas ◽  
Compressor Design ◽  
Design Selection ◽  
Inlet Conditions

This paper describes the design and application of reciprocating compressors for fuel gas service. In fuel gas services and particularly power generation it is important to minimize all parasitic losses. Efficiency over a range of operating conditions requires sophisticated control systems and the paper describes the merits of each system and their effect on operating cost. Some of the important operational considerations are described together with major design features. The use of staging and the advantages of a modular approach to compressor design are also covered, which demonstrates the suitability of the reciprocating compressor for fuel gas service particularly when variation of inlet conditions cannot be avoided.

Effects of Rotating Inlet Distortion on Compressor Stability With Stall Precursor-Suppressed Casing Treatment

2015 ◽  
Vol 137 (11) ◽  
Author(s):  
Xu Dong ◽  
Dakun Sun ◽  
Fanyu Li ◽  
Donghai Jin ◽  
Xingmin Gui ◽  
...  
Keyword(s):  
Stability Problem ◽  
Axial Fan ◽  
Stall Margin ◽  
Casing Treatment ◽  
Inlet Distortion ◽  
Large Size ◽  
Flow Disturbances ◽  
Stall Margin Improvement ◽  
The Stability ◽  
Stall Precursor

This paper conducts an experimental research of rotating inlet distortion on a low-speed large size test compressor with emphasis on the stability problem of axial fan/compressors, and the stall margin enhancement with a kind of stall precursor-suppressed (SPS) casing treatment. Some results on compressor stall margin and prestall behavior under the restriction of rotating inlet distortion are presented. The experimental results show that whether the inlet distortion is co-rotating or counter-rotating, the SPS casing treatment can still improve the stall margin without leading to additional efficiency loss caused by such configuration. The experiment results also show that the mechanism of the stall margin improvement with such casing treatment is associated with delaying the nonlinear development of the stall precursor waves and weakening the unsteady flow disturbances in a compression system.

Axial-Slot Casing Treatments Improve the Efficiency of Axial Flow Compressors: Aerodynamic Effects of a Rotor Redesign

2013 ◽  
Author(s):  
J. Anton Streit ◽  
Frank Heinichen ◽  
Hans-Peter Kau
Keyword(s):  
Axial Flow ◽  
Operating Conditions ◽  
Tip Clearance ◽  
Negative Effects ◽  
Stall Margin ◽  
Casing Treatment ◽  
Transonic Compressor ◽  
Compressor Rotor ◽  
Flow Phenomena ◽  
Casing Treatments

A state-of-the-art transonic compressor rotor has a distinct potential for increased efficiency if modified for improved interaction with an axial-slot type casing treatment. Reducing the number of blades and thus the surface lowers friction losses but increases tip clearance effects and deteriorates the stall margin due to the higher aerodynamic blade loading. The latter two negative effects can be compensated for by the casing treatment, thus restoring the required stall margin and gaining an overall reduction of losses. For the specific compressor rotor under investigation, the potential in polytropic efficiency is as high as 0.7%. The present study was performed using time-accurate CFD (URANS) simulations. Both the reference rotor as well as the modified design are analyzed regarding their interaction with the casing treatment. The traceability of the conclusions is assured by interpreting the detailed flow phenomena. The newly designed rotor is found to be favorably influenced by the casing treatment at design operating conditions whilst the reference only benefits at throttled operating points. Casing treatments are commonly used to broaden the operating range of existing compressors without changing the design of the compressor rotor itself. This study aims to show the possible transformation of this potential in the stall margin into efficiency at design operating conditions by implementing an appropriate rotor design.

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