“…The pressure recovery coefficient of the U-bend and the pressure loss coefficient of the return channel are depicted in Figure 8 as a function of the flow coefficient, for the three studied width ratios. The pressure loss coefficient, 47 C L , the pressure recovery coefficient, C p , and the total-to-total pressure ratio, normalΠtt, are calculated according to the following relations 48 :where pt and ps represent the total pressure and the static pressure, respectively. The subscripts i and j show the upstream and downstream sections, respectively.Figure 7.The effects of the return channel inlet width on the stage pressure ratio as a function of the flow coefficient.Figure 8.The pressure loss coefficient of the return channel, C L, RCH , and the U-bend pressure recovery coefficient, C P, bend , as a function of the flow coefficient for three width ratios.…”
Section: Resultsmentioning
confidence: 99%
“…The pressure recovery coefficient of the U-bend and the pressure loss coefficient of the return channel are depicted in Figure 8 as a function of the flow coefficient, for the three studied width ratios. The pressure loss coefficient, 47 C L , the pressure recovery coefficient, C p , and the total-to-total pressure ratio, Π tt , are calculated according to the following relations 48 : where p t and p s represent the total pressure and the static pressure, respectively. The subscripts i and j show the upstream and downstream sections, respectively.…”
Section: The Effects Of the Inlet Width Of The Return Channelmentioning
In this paper, steady RANS (Reynolds-Averaged Navier-Stokes) numerical modeling of the return system of a centrifugal compressor is carried out to investigate the effects of various geometrical parameters on the aerodynamic performance of the return system. The effects of using splitter vanes in the return-channel, the width ratio of the return channel and the diverging angle of the walls are examined. Numerical results revealed that using splitter vanes can enhance the stage averaged pressure ratio and polytropic efficiency by 0.74 and 3.21%, respectively. Results showed that increasing the width ratio can enhance the efficiency and pressure ratio near the choke region, however, it has marginal effects on the performance at low flow coefficients. Results also showed that, due to the negligible effects of the diverging angle on the stage performance, using diverging hub wall can reduce the total axial length of the multistage compressor. Finally, a new return system is designed based on the combination of the best geometrical parameters found in the current study. Simulation results demonstrated that the average pressure ratio and efficiency of the compressor have been improved by 0.99% and 4%, respectively, by the newly developed return system compared to the original design.
“…The pressure recovery coefficient of the U-bend and the pressure loss coefficient of the return channel are depicted in Figure 8 as a function of the flow coefficient, for the three studied width ratios. The pressure loss coefficient, 47 C L , the pressure recovery coefficient, C p , and the total-to-total pressure ratio, normalΠtt, are calculated according to the following relations 48 :where pt and ps represent the total pressure and the static pressure, respectively. The subscripts i and j show the upstream and downstream sections, respectively.Figure 7.The effects of the return channel inlet width on the stage pressure ratio as a function of the flow coefficient.Figure 8.The pressure loss coefficient of the return channel, C L, RCH , and the U-bend pressure recovery coefficient, C P, bend , as a function of the flow coefficient for three width ratios.…”
Section: Resultsmentioning
confidence: 99%
“…The pressure recovery coefficient of the U-bend and the pressure loss coefficient of the return channel are depicted in Figure 8 as a function of the flow coefficient, for the three studied width ratios. The pressure loss coefficient, 47 C L , the pressure recovery coefficient, C p , and the total-to-total pressure ratio, Π tt , are calculated according to the following relations 48 : where p t and p s represent the total pressure and the static pressure, respectively. The subscripts i and j show the upstream and downstream sections, respectively.…”
Section: The Effects Of the Inlet Width Of The Return Channelmentioning
In this paper, steady RANS (Reynolds-Averaged Navier-Stokes) numerical modeling of the return system of a centrifugal compressor is carried out to investigate the effects of various geometrical parameters on the aerodynamic performance of the return system. The effects of using splitter vanes in the return-channel, the width ratio of the return channel and the diverging angle of the walls are examined. Numerical results revealed that using splitter vanes can enhance the stage averaged pressure ratio and polytropic efficiency by 0.74 and 3.21%, respectively. Results showed that increasing the width ratio can enhance the efficiency and pressure ratio near the choke region, however, it has marginal effects on the performance at low flow coefficients. Results also showed that, due to the negligible effects of the diverging angle on the stage performance, using diverging hub wall can reduce the total axial length of the multistage compressor. Finally, a new return system is designed based on the combination of the best geometrical parameters found in the current study. Simulation results demonstrated that the average pressure ratio and efficiency of the compressor have been improved by 0.99% and 4%, respectively, by the newly developed return system compared to the original design.
“…This last action, apart from later experimental studies, is the key part of the design process: the results of numerical tests were the basis for the decision to approve the geometry and subsequent certification of the product. Numerical fluid and structural analyses were used to determine working conditions as well as the state of loads and deformations of the tested object 7 , 8 . The most realistic and accurate results are obtained through the cooperation of both tools: fluid–structure interactions (FSI) analyses to take into account the simulated distribution of aerodynamic loads 9 – 12 , which appear at the boundaries of the flow domain, in the numerical structural analysis 13 – 15 .…”
This study aims to quantify and assess qualitatively the impact of modeling simplifications used to represent inertial and aerodynamic loads on the stresses and structural deformations of a centrifugal compressor in operation. The research object is the compressor of the high-pressure line of the DGEN 380 bypass turbine engine. Based on the virtual dynamometer WESTT CS/BV, the gas-dynamic parameters at the entrance to the centrifugal compressor and after the stage are determined. These values were used as initial parameters for numerical flow analysis. As part of the numerical strength analyses, a series of several load configurations were carried out: spin only, spin and inlet pressure normally applied on the working surface of the rotor blade, spin and outlet pressure normally applied on the working surface of the rotor blade, and one-way fluid–structure interaction analysis taking into account the aerodynamic loads with and without spinning. Based on the simulations, the level of similarity of a given load configuration with the last analysis, adopted as the reference, was determined. It was observed that in terms of the stress state, the rotational analysis taking into account the pressure on both sides of the blade gives satisfactory results, but the strain values are overestimated. The results obtained and the method of evaluation of compressor results can be used in research in the area of aviation, automotive, and refrigeration industries.
“…Turbomachinery is undoubtedly important for modern industrialized society, especially in the fields of small and medium-sized aero-engines, refrigeration, chemical factory, vehicles, etc. [1][2][3][4][5]. As power machinery, a wide, high-efficiency operating range is required for compressors, considering not only the efficiency but also the stability and safety [6][7][8].…”
A review on the rotating stall in the vaneless diffuser of centrifugal compressors is presented showing that different stall modes characterized by different numbers of cells can be detected within the diffuser even if the operating condition remains unchanged. The interaction between the inlet perturbation and the stall cells near the diffuser outlet is supposed to be the trigger of the stall mode transformation. In order to determine if the inlet perturbation will interact with the downstream stall cells, a characteristic time analysis is proposed to estimate the characteristic time of the perturbation in radial and tangential directions. An additional theoretical model which focused on the development of the vaneless diffuser rotating stall is presented to determine the propagation velocity of the cells. The comparison between the characteristic time in two directions shows that one stall mode is able to evolve into another stall mode if a critical condition is met, and the stall mode transformation is more likely to start from a mode with a higher number of cells and is more likely to occur in the diffuser with a large radius ratio. Experimental results are also employed to validate the proposed critical condition, and good agreements are obtained.
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