Numerical simulations have been performed to investigate tip clearance effect on throughflow and performance of a centrifugal compressor which has the same configuration of impeller with six. Abstract tip clearance effects on flow field of a low speed centrifugal compressor performance is tested experimentally by using partial shroud ps attached to the rotor blade tip at three values of tip clearances i. The numerical results were in good agreement with the experimental. The axial clearance between the tip of the blades of an unshrouded impeller and its stationary shroud has been varied to study its effect on overall compressor performance. Centrifugal compressor tip clearance and impeller flow. An electromagnetic actuator is used to pull the compressor impeller axially to reduce the tip clearance.
Study of secondary flow modifications at impeller exit of a. Investigation into the effect of tip clearance on centrifugal. The second compressor simulated was a honeywell turbopump centrifugal compressor hcc. Timeresolved pressure measurements have been performed along the casing of a scaledup model of a small. In this paper, the tip clearance flow in the subsonic impeller is. Pdf losses and blade tip clearance for a centrifugal. The tip leakage flow thus would have dominant effect on the performance of a compressor. The tip clearance effects on the centrifugal compressor vaneless diffuser flow fields at offdesign conditions conference paper pdf available april 20 with 257 reads how we measure reads. Role of tip clearance flow on axial compressor stability by huu duc vo b. The development of highperformance centrifugal compressor for the application of highspeed turbomachinery such as turbochargers and micro gas turbines needs to be addressed urgently due to the fact that it offers enormous opportunities to control the exhaust emission in automobile engines and makes it more environmentally friendly. Hence, improvements in compressor efficiency lead to energy savings and reduce environmental impacts. The aim of this paper is to investigate the design in similarity of a centrifugal compressor for micro gas turbine and the related scaling effects on performance using cfd investigations. Centrifugal compressors are also similar to centrifugal pumps of the style shown in the adjacent figures.
Results indicate that stage performance can easily be correlated with the. Influences of distuned tip clearance on the discrete aerodynamic noise in centrifugal compressor mingxu qi, meijie zhang, chaochen ma isromac 2016 international symposium on transport phenomena and dynamics of rotating machinery hawaii, honolulu april 1015, 2016 abstract. Investigation into the effect of tip clearance on centrifugal compressor performance. Tip clearance effects on performance of a centrifugal compressor s. Tip clearance effects on performance of a centrifugal. Design of a highperformance centrifugal compressor with. Pdf tip clearance effect on throughflow and performance. Mar 23, 2015 the axial clearance between the tip of the blades of an unshrouded impeller and its stationary shroud has been varied to study its effect on overall compressor performance. The compressor overall performance and diffuser flow fields were studied for each of.
The hcc was simulated for three tip clearances at six wheel speeds. The tip clearance of the thin compressor was increased in 0. Design of a highperformance centrifugal compressor with new. Tip leakage significantly affects the axialcompressor performance i. The effect of tip leakage flow on the passage flow differs. Abstracttip clearance effects on flow field of a low speed centrifugal compressor performance is tested experimentally by using partial shroud ps attached to the rotor blade tip at three values of tip clearances i. Understand your process, as well as the advantages and disadvantages of each centrifugal compressor configuration, in order to choose the optimal centrifugal compressor for your application. International journal of research in engineering and technology, 2, 447453. Investigation of a centrifugal compressor and study of the area ratio and tip clearance effects on performance. Tip clearance in centrifugal compressor causes the leakage of high pressure fluid from pressure surface to suction surface of the impeller blade, making the flow. Pdf the tip clearance effects on the centrifugal compressor.
They are designed for long life, low maintenance and continuous service in dirty and corrosive applications such as petrochemical plants, refineries, natural gas processing, coal gasification and power stations. Backman, experimental study of centrifugal compressor tip clearance and vaneless diffuser flow fields, proceedings of the institution of mechanical engineers, part a. Six operating conditions were investigated at each tip clearance and wheel speed. Centrifugal compressor 1 mechanical engineering in. Tip clearance in centrifugal compressor causes the leakage of high pressure fluid from pressure surface to suction surface of the impeller blade, making the flow field highly complex and effecting the performance. The diffuser flow fields were studied with probe traverses for total temperature, total pressure, and flow angle, along. Each diffuser configuration was tested with four different tip clearances. Impeller tip clearance is set as 2% of the impeller width at outlet. Numericalsimulationswere conducted for six centrifugal compressor impellers in which the tip clearance height varied linearly from the. This paper presents a numerical investigation of the effects of a nonuniform tip clearance profile on the performance and flow field in a centrifugal compressor with a vaneless diffuser. The present paper presents the numerical analysis for a transonic centrifugal compressor using steady state cfd. Compressors consume a considerable portion of the electricity used in the industrial sector. The role of tip clearance flows in the stall inception process is still debated.
The key difference between such compressors and pumps is that the compressor working fluid is a gas compressible and the pump working fluid is liquid incompressible. The size of the clearance is one of the most important parameters in compressor design. Design of a centrifugal compressor for micro gas turbine. The design and test results of a failsafe active tip clearance control system for a centrifugal compressor are presented. Investigation of scaling and tip clearance effects dario barsi, alberto bottino, andrea perrone, luca ratto, pietro zunino department of mechanical, energy, management and transportation engineering, university of genova, genova, italy abstract.
Tip clearance effects on flow field of a low speed centrifugal compressor without and with partial shroud ps attached to the rotor blade tip at three values of tip clearance, viz. Detailed specifications of the compressor are given in. A vital aspect is the tip clearance control between impeller and shroud casing over the total operating range. The compressor under investigation consisted of an inlet nozzle, a 3d open impeller with full inducer, a parallelwall vaneless diffuser and a collector. The losses in these compressors are dominated by tip clearance flow. The flow in the rotor tip clearance gap in an axial compressor influences the loss levels and the stall onset point. For steady state analysis the simulation is done at an instantaneous relative position between impeller blade and diffuser vane. The leakage flow through a tipclearance region, together with the consequent decrease in lift and increase in drag, has been one of the known causes of turbine and compressor inefficiency. Study of secondary flow modifications at impeller exit of. At all clearance values, global parameters of efficiency and head coefficient were assessed for the rotor and the stage. The efficiency of an unshrouded centrifugal compressor suffers from leakage flow over the blade tips.
Numerical simulation of the impeller tip clearance effect on. The stage overall performance along with the diffuser flow fields were studied. Abstracttip clearance effects on flow field of a low speed centrifugal compressor performance is. This study focuses in particular on the magnitude and location of the wake. Centrifugal impeller, diffuser, stage, tip clearance, numerical simulation, entropy. Incre ments at design speed with an inlet total pressure of 14 psia.
The leakage flow through a tip clearance region, together with the consequent decrease in lift and increase in drag, has been one of the known causes of turbine and compressor inefficiency. Centrifugal compressor tip clearance and impeller flow article in journal of mechanical science and technology 3011. Three vaneless diffuser designs, varying in diffuser width, for centrifugal compressor were studied experimentally. Clearance effects on the onset of instability in a centrifugal compressor this report intends to shed an insight into the effect of large relative tip clearances on the onset of instability in a highly loaded centrifugal compressor. Tipclearance flow and losses for an compressor blade. Tip clearance changes with engine aging turbine tip clearance changes over the life of the engine, typically 2050 mils engine dynamics engine accel and decel will change the tip clearance goal of turbine tip clearance control is to have a tighter control of the tip. Using the radial compressor for a small gas turbine engine, developed at bmw rollsroyce, the importance of tip clearance control is demonstrated. The tip clearance effects on the centrifugal compressor.
Jul 30, 20 increasing demand for downsizing of engines to improve co2 emissions has resulted in renewed efforts to improve the efficiency and expend the stable operating range of the centrifugal compressors used in petrochemical equipment and turbochargers. This work is part of a research project carried out by the department dime of the university of genova, with the purpose of investigating the performance of a micro gas turbine in the change from 100 kw. This paper investigates the impact of tip leakage on the performance of centrifugal compressor systems for relative clearance ratios, ranging from 3 up to 15 %. Six impellers with different tip clearance profiles were tested in the flow simulations. The open impeller lacks the second bounding surface shroud connecting the tip. Simulation and optimization of an axial compressor.
All results were obtained through 3d cfd simulations carried out with the komega sst model. Experimental study of the effect of the tip clearance to the diffuser flow field and stage performance of a centrifugal compressor. Global analysis of tip clearance influence on centrifugal. Thermal tip clearance control for centrifugal compressor of. Dec 04, 2017 tip leakage significantly affects the axial compressor performance i. The centrifugal compressors have a wide range of applications especially for power plants for small aircraft and helicopters, in process industries, compression of. Increasing demand for downsizing of engines to improve co2 emissions has resulted in renewed efforts to improve the efficiency and expend the stable operating range of the centrifugal compressors used in petrochemical equipment and turbochargers.
In this paper a case study of a transsonic centrifugal compressor at various tip gap values is presented. It has long been recognized that the tip clearance of a centrifugal compressor is of paramount importance for aerodynamic performances, which means that accurately predicting the flow field in this region is crucial for accurate prediction of performances by means of cfd codes. Centrifugal compressor tip clearance and impeller flow lutpub. Tip clearance effects on performan ce of a centrifugal comp ressor s. The actuator acts against a preloaded belleville spring. Design considerations for tip clearance sensitivity of.
Manual purpose to be used for selection, application into the system, power and cooling water estimation. Numerical simulation of the impeller tip clearance effect. In this paper, the tip clearance flow in the subsonic impeller is numerically. Pdf investigation of a centrifugal compressor and study of. Proceedings of asme turbo expo, copenhagen, denmark, 1115 june 2012, paper no. Storer and cumpsty, for example, suggest that most of the loss often attributed to tip clearance effects are probably due to other causes 19.
This manual does not for designing centrifugal compressor and those parts. Impact of large tip clearance ratios on the performance of. Generally, the tip clearance is uniform from the leading edge to the trailing edge of the compressorblade section at the tip. Pdf tip clearance effect on throughflow and performance of. Generally the centrifugal compressor impellers are of radial type because of. The method of testing the compressor is run at a constant speed at 2000rpm. Effects of tip clearance on through flows and performance of a centrifugal compressor impeller with six different tip clearances were numerically studied using cfxtascflow. Thermal tip clearance control for centrifugal compressor. The influence of tip clearance on centrifugal compressor.
In an axial compressor, the proximity of the shroud and ow from nearby blade passages adds another dimension to the complexity of the. Design of a highperformance centrifugal compressor with new surge margin improvement technique for high speed turbomachinery. Influences of distuned tip clearance on the discrete. Aug 23, 2017 5 schleer, matthias, and others, 2008, clearance effects on the onset of instability in a centrifugal compressor, journal of turbomachinery july 2008, vol. Experimental study of centrifugal compressor tip clearance. Clearance effects on the onset of instability in a. Three centrifugal compressor vaneless diffuser configurations, varying in diffuser width, were studied experimentally. Investigation of scaling and tip clearance effects fulltext html xml download as pdf size. Introduction in recent years, mgt have been more and more used as cogeneration systems for distributed power generation. Institute of energy, lappeenranta university of technology, lappeenranta, finland, ahti.
Effect of nonuniform tip clearance on the performance of. Higher and lower flow stage ratings are derived from. Study on the performance of a centrifugal compressor. Eisenlohr and chladek 1994 qualitatively analyzed the effect of relative tip clearance of centrifugal compressor on the performance through measurements. Along with the diffuser width, the tip clearance was altered. On the nature of tip clearance flow in subsonic centrifugal. Sorokes dresserrand selecting a centrifugal compressor inlet pressure p1 temperature t1. Tip clearance effects on performance of a centrifugal compressor.
Abstract tip clearance effects on flow field of a low speed centrifugal compressor performance is tested experimentally. Pdf investigation of a centrifugal compressor and study. Generally, the tip clearance is uniform from the leading edge to the trailing edge of the compressor blade section at the tip. Elliott has been manufacturing single stage centrifugal compressors for over 90 years.
The tip leakage analysis is conducted numerically on an experimentally validated centrifugal compressor system operating with refrigerant r4a. Improved modeling for compressors with large tip clearance. Centrifugal compressor impellers may be open or shrouded see figure 1. The centrifugal compressor is to study the effect of tip clearance on the performance characteristics and the wall static pressure for a different flow coefficient. Effects of a nonuniform tip clearance profile on the. The impeller geometry should be compressor using a five. Compressor, tip clearance, partial shroud, ps on tip of the rotor blade, casing, tip leakage flow. The total number of diffuser vanes in vd configuration is 22 and that in lsvd is 11. The controlled variable is an averaged, tiptoshroud clearance which. Professors, department of mechanical engineering, jntuce, anantapur. The tip clearance can have a large e ect on performance. In an axial compressor, the proximity of the shroud and ow from nearby blade passages adds another dimension to the complexity of the ow in this region.
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