scholarly journals Experimental Study on Effects of Adjustable Vaned Diffusers on Impeller Backside Cavity of Centrifugal Compressor in CAES

Energies ◽  
2021 ◽  
Vol 14 (19) ◽  
pp. 6187
Author(s):  
Zhihua Lin ◽  
Zhitao Zuo ◽  
Wenbin Guo ◽  
Jianting Sun ◽  
Qi Liang ◽  
...  
Keyword(s):  
Centrifugal Compressor ◽  
Static Pressure ◽  
Internal Flow ◽  
Operating Conditions ◽  
Test Facility ◽  
Angle Change ◽  
Temperature Loss ◽  
Impeller Outlet ◽  
Compressor Performance ◽  
Variable Operating Conditions

The impeller backside cavity (IBC) is a unique structure of centrifugal compressor in compressed air energy storage (CAES) systems, which affects the aerodynamic performance of centrifugal compressor, and the angle change of the downstream coupled adjustable vaned diffusers (AVDs) will affect the flow field inside the cavity and compressor performance. This paper relies on the closed test facility of the high-power intercooling compressor to measure static pressure and static temperature at different radii on the static wall of the IBC. The coupling relationship between the IBC and compressor under variable operating conditions is analyzed, and the influence of AVDs on the internal flow in IBC is studied. The results show that static pressure and static temperature rise along the direction of increasing radius, but static temperature drops near the coupling between the impeller outlet and the cavity inlet. Under AVDs’ design angle, static pressure and static temperature at each point, static pressure loss and static temperature loss in the direction of decreasing radius all increase as the flow decreases. Under variable AVDs’ angles, static pressure and static temperature will change differently, and respective loss will also be different.

Experimental Inverstigations On the Pressure Fluctuations in the Sealing Gap of Dry Gas Seals with Embedded Pressure Sensors

2021 ◽  
Author(s):  
Jingjing Luo ◽  
Dieter Brillert
Keyword(s):  
High Speed ◽  
Gas Flow ◽  
Static Pressure ◽  
Pressure Sensors ◽  
Operating Conditions ◽  
Test Facility ◽  
Experimental Investigations ◽  
Mechanical Seals ◽  
Process Gas ◽  
Sealing Gap

Abstract Dry gas lubricated non-contacting mechanical seals (DGS), most commonly found in centrifugal compressors, prevent the process gas flow into the atmosphere. Especially when high speed is combined with high pressure, DGS is the preferred choice over other sealing alternatives. In order to investigate the flow field in the sealing gap and to facilitate the numerical prediction of the seal performance, a dedicated test facility is developed to carry out the measurement of key parameters in the gas film. Gas in the sealing film varies according to the seal inlet pressure, and the thickness of gas film depends on this fluctuated pressure. In this paper, the test facility, measurement methods and the first results of static pressure measurements in the sealing gap of the DGS obtained in the described test facility are presented. An industry DGS with three-dimensional grooves on the surface of the rotating ring, where experimental investigations take place, is used. The static pressure in the gas film is measured, up to 20 bar and 8,100 rpm, by several high frequency ultraminiature pressure transducers embedded into the stationary ring. The experimental results are discussed and compared with the numerical model programmed in MATLAB, the characteristic and magnitude of which have a good agreement with the numerical simulations. It suggests the feasibility of measuring pressure profiles of the standard industry DGS under pressurized dynamic operating conditions without altering the key components of the seal and thereby affecting the seal performance.

The performance of a centrifugal compressor with a tandem impeller in off-design conditions

2019 ◽  
Vol 234 (2) ◽  
pp. 156-172 ◽  
Author(s):  
Ziliang Li ◽  
Xingen Lu ◽  
Ge Han ◽  
Yanfeng Zhang ◽  
Shengfeng Zhao ◽  
...  
Keyword(s):  
Centrifugal Compressor ◽  
Performance Enhancement ◽  
Pressure Ratio ◽  
Operating Conditions ◽  
Complex Flow ◽  
Maximum Enhancement ◽  
Operating Range ◽  
Wide Range ◽  
Compressor Performance ◽  
Low Efficiency

Centrifugal compressors often suffer relatively low efficiency and a terrible operating range particularly due to the complex flow structure and intense impeller/diffuser interaction. Numerous studies have focused on improving the centrifugal compressor performance using many innovative ideas, such as the tandem impeller, which has become increasingly attractive due to its ability to achieve the flow control with no additional air supply configurations and control costs in compressor. However, few studies that attempted to the investigation of tandem impeller have been published until now and the results are always contradictory. To explore the potential of the tandem impeller to enhance the compressor performance and the underlying mechanism of the flow phenomena in the tandem impellers, this paper numerically investigated a high-pressure-ratio centrifugal compressor with several tandem impellers at off-design operating speeds. The results encouragingly demonstrate that the tandem impeller can achieve a performance enhancement over a wide range of operating conditions. Approximately 1.8% maximum enhancement in isentropic efficiency and 5.0% maximum enhancement in operating range are achieved with the inducer/exducer circumferential displacement of [Formula: see text] = 25% and 50%, respectively. The observed stage performance gain of the tandem impellers decreases when the operating speed increases due to the increased inducer shock, increased wake losses, and deteriorated tandem impeller discharge flow uniformity. In addition, the tandem impeller can extend the impeller operating range particularly at low rotation speeds, which is found to be a result from the suppression of the low-momentum fluid radial movement. The results also indicate that the maximum flux capacity of the tandem impeller decreases due to the restriction of the inducer airfoil Kutta–Joukowsky condition.

Enhancing the Centrifugal Compressor Performance Map Measurements Through a Developed One–Dimensional Calculation Tool to Analyse Local Flow Phenomena

2014 ◽  
Author(s):  
Matthias Hamann ◽  
Elias Chebli ◽  
Markus Müller ◽  
Alexander Krampitz
Keyword(s):  
Centrifugal Compressor ◽  
Static Pressure ◽  
Flow Characteristics ◽  
Local Flow ◽  
One Dimensional ◽  
Casing Treatment ◽  
Surge Margin ◽  
Performance Map ◽  
Flow Phenomena ◽  
Compressor Performance

Centrifugal compressors for automotive turbochargers have large influence on the operation characteristic of combustion engines. Especially the improvement of the surge margin is one of the most important development targets. Thereby, a reliable detection of local flow phenomena within the compressor stage is necessary and a procedure to gain this information from standard measurement data is discussed in this paper. A one–dimensional calculation methodology for a single-stage centrifugal compressor with a vaneless diffuser and casing treatment is presented. The tool calculates the flow properties at the impeller inlet and exit as well as at diffuser exit, based on the measured inlet and outlet data and the geometry information of the compressor. The calculated flow characteristics are plotted within the measured compressor performance map to show local flow parameters. The unsteady recirculation flow within the casing treatment, the inflow angle and the total pressure losses are considered. The tool is validated on different compressor sizes. Thereby the compressor is equipped with static pressure measuring points at the impeller inlet and exit as well as at the diffuser exit. The calculated static pressure correlated well with the measured data with an accuracy of 2 % to 5 % on 95 % of the operating range. In this paper an experimental parameter study is executed in order to improve the surge margin. Thereby the geometry of the diffuser and the casing treatment is varied and the compressor performance is measured on a turbocharger test rig. The calculation of the flow angles and other flow characteristics within the diffuser enables one to find out whether surge is triggered through the diffuser or the impeller.

scholarly journals The Performance of Centrifugal Compressor Channel Diffusers

1982 ◽  
Author(s):  
C. Rodgers
Keyword(s):  
Centrifugal Compressor ◽  
Static Pressure ◽  
Diffusion Rate ◽  
Performance Criteria ◽  
Stream Velocity ◽  
Test Results ◽  
Maximum Value ◽  
Compressor Performance ◽  
Velocity Diffusion ◽  
Channel Type

Test results pertaining to the characteristics of single-stage centrifugal compressors with backswept impellers and channel-type diffusers are presented and analyzed to formulate major performance criteria influencing maximum diffusion capability. For any given stage, it was determined that stage surge (when triggered by diffuser stall), occurred near a constant mean stream velocity diffusion ratio between the impeller tip and diffuser throat. This diffusion ratio attained a maximum value of 1.8 for impeller tip Mach numbers less than unity, but was not unique for all stages, being more intimately coupled with throat blockage accumulation as a function of diffusion rate. This was identified by testing some vaned diffusers beyond the stall limit where rapid blockage accumulation precipitated an immediate decrease in channel diffuser and system static pressure recovery. The results of various experiments in the vaneless space are also described to illustrate the sensitivity of the vaneless space flow upon centrifugal compressor performance.

Experimental Investigation of the Flow in the Pipe Diffuser of a Centrifugal Compressor Stage Under Selected Parameter Variations

2009 ◽  
Author(s):  
Uwe Zachau ◽  
Reinhard Niehuis ◽  
Herwart Hoenen ◽  
David C. Wisler
Keyword(s):  
Centrifugal Compressor ◽  
Measurement Techniques ◽  
Operating Conditions ◽  
Tip Clearance ◽  
Test Facility ◽  
Experimental Investigations ◽  
Pressure Side ◽  
Compressor Stage ◽  
Diffuser Flow ◽  
Parameter Variations

On a centrifugal compressor test facility various experimental investigations have been carried out contributing a valuable gain in knowledge on the fundamental flow physics within passage type diffusers. An extensive measurement series using various steady, unsteady and laser optical measurement techniques has been performed to detect the unsteady, highly three dimensional diffuser flow under various realistic operating conditions. Zachau et al. [1] presented the test facility and the results gathered under nominal conditions. As a follow-up the results of investigated parameter variations are now presented, covering bleed variations, impeller tip clearance and impeller-diffuser misalignment studies. The data is compared to the benchmark created from the nominal baseline data sets and evaluated with respect to the compressor stage performance. Zachau et al. [1] found that under nominal conditions the flow in the pipe diffuser separates on the pressure side in the first half of the pipe. In the last 30% of the pipe hardly any deceleration of the flow takes place. From this, special attention is given to the investigated parameter variations regarding a first proposal for a diffuser design change, which consists in shortening the diffuser. The results for each parameter variation are evaluated in detail in direct comparison to the nominal baseline configuration underlining the conclusion made earlier that the diffuser flow always separates on the pressure side with negligible deceleration in the last third of the diffusing pipe.

Variable Inlet Guide Vane Effect on Centrifugal Compressor Performance in Wet Gas Flow

2016 ◽  
Author(s):  
Levi André B. Vigdal ◽  
Lars E. Bakken
Keyword(s):  
Centrifugal Compressor ◽  
Guide Vane ◽  
Flow Direction ◽  
Pressure Ratio ◽  
Operating Conditions ◽  
Inlet Guide Vane ◽  
Compressor Stage ◽  
Guide Vanes ◽  
Wet Gas ◽  
Compressor Performance

The introduction of variable inlet guide vanes (VIGVs) upfront of a compressor stage affects performance and permits tuning for off-design conditions. This is of great interest for emerging technology related to subsea compression. Unprocessed gas from the wellhead will contain liquid condensate, which affects the operational condition of the compressor. To investigate the effect of guide vanes on volume flow and pressure ratio in a wet gas compressor, VIGVs are implemented upfront of a centrifugal compressor stage to control the inlet flow direction. The guide vane geometry and test rig setup have previous been presented. This paper documents how changing the VIGV setting affects compressor performance under dry and wet operating conditions. The reduced performance effect and operating range at increased liquid content are of specific interest. Also documented is the change in the VIGV effect relative to the setting angle.

Study and Investigation on the Mach of Impeller Outlet and Diffuser Inlet in Stamping and Welding Centrifugal Pump

2012 ◽  
Vol 229-231 ◽  
pp. 2454-2458
Author(s):  
Jian Jun Gan ◽  
Jie Gang Mou ◽  
Shui Hua Zheng ◽  
Bo Zhu
Keyword(s):  
Centrifugal Pump ◽  
Experimental Research ◽  
Static Pressure ◽  
Flow Characteristics ◽  
Internal Flow ◽  
Area Ratio ◽  
Cfd Simulations ◽  
Impeller Outlet ◽  
And Performance

Based on CFD simulations and experimental research, this paper studied the mach of impeller outlet and diffuser inlet in stamping and welding centrifugal pump. The influence of area ratio Y of impeller outlet to diffuser inlet on pump internal flow characteristics and performance was studied. Five different area ratio pump models were analyzed. The results indicate that as the area ratio Y= F3/F2 increase, the velocity of fluid in diffuser inlet decreases continuously, the average static pressure of diffuser outlet increases, and the head and efficiency of the pump are risen. When the area ratio increases from Y=1.48 to Y=3.49, the head increases about 3.0% and the efficiency about 2.0%.

Investigation of Stall Process in a Centrifugal Compressor With a Volute Under Transonic Conditions

2019 ◽  
Author(s):  
Ce Yang ◽  
Wenli Wang ◽  
Hanzhi Zhang ◽  
Yanzhao Li ◽  
Ding Tong ◽  
...  
Keyword(s):  
Flow Field ◽  
Centrifugal Compressor ◽  
Static Pressure ◽  
Cell Formation ◽  
Internal Flow ◽  
Growth Zone ◽  
Asymmetric Structure ◽  
Stall Inception ◽  
Stall Cells ◽  
Inlet Conditions

Abstract In a centrifugal compressor with a volute, the internal flow field is circumferentially nonuniform owing to the asymmetric structure of the volute. Currently, the mechanisms by which the volute influences the stall inception circumferential position and the stall process in a transonic centrifugal compressor are not clear. In this study, the stall process in the centrifugal compressor with a volute is investigated under transonic inlet conditions. Obtained by experimental and simulation results, the static pressure distributions around the casing wall are compared with each other. Thereafter, an unsteady simulation is conducted on the stall process under transonic inlet conditions. By analyzing the stall cell evolution pattern at the impeller inlet, the stall process can be divided into three stages: stall onset, stall development, and stall maturation. The spike-type stall inceptions occur twice at the tip in the circumferential 135° position of the impeller inlet. This circumferential position is also the affected position of the high static pressure region induced by the volute tongue. Because of the circumferentially nonuniform flow field, there is a stall cell decay zone and a stall cell formation/growth zone at the impeller inlet. For the compressor under study, the approximate circumferential range of 135° to 270° is the decay zone, and the circumferential range of 270° to 360° is the formation/growth zone. The stall inception cannot occur in the decay zone. However, the stall cells can pass through the decay zone when the stall cell size is large enough. The first stall inception cannot propagate circumferentially, while the second one can. The propagation speed of stall cells in the circumferential direction is at approximately 70% of the rotational speed of impeller.

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