• Proceedings of the KSME Conference
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• 2000.04b
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• pp.193-198
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• 2000

For an inverter-driven compressor, the discharge temperature increased with a rise of frequency, Therefore, it is necessary to control the discharge temperature at high frequencies in order to obtain system reliability and efficiency. This paper describes the effects of liquid injection system on the performance of an inverter-driven scroll compressor. Experiments were performed at ASHRAE-T conditions. Frequency was altered from 45 to 105Hz. As results of the present work, the refrigerant discharge temperature fur the injection system was dropped approximately $10{\sim}20^{\circ}C$ as compared to those for the non-injection system. The COP of the compressor was improved approximately $0.8{\sim}9.3%$ at high frequencies(75, 90, and 105 Hz).

• Proceedings of the KSME Conference
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• 2003.11a
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• pp.834-839
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• 2003

In the present study, the performance characteristics and the number of stall cells during rotating stall of a centrifugal air compressor were experimentally investigated. If the flow coefficient is lower than 0.150, the static pressure at impeller inlet is higher than that at inlet duct And reverse flow is observed under these flow coefficient region. Maximum adiabatic efficiency is obtained for the tested compressor around flow coefficient 0.128, and it is independent of compressor rotating speed. The number of stall cells and their rotational speeds are distinctive features of the rotating stall phenomenon. The present study is mainly concerned with the number of stall cells and their rotational speeds. The interpretation method of visualization is based on the pressure distribution in the circumference pressure fields while plotting the pressure and its harmonics variations in time in polar coordinates.

• 유체기계공업학회:학술대회논문집
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• 2005.12a
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• pp.517-524
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• 2005

An aerodynamic design for centrifugal compressor which was applied to medium speed diesel engine has done. First of all, exact compressor specifications must be defined by accurate engine system matching. This matching program has been developed. Using the mean1ine prediction method, geometric design and performance curve for compressor was done and verified by comparing three dimensional viscous CFD results. The deviation at the design point was about 2.3%. Combustor has been designed and manufactured for the performance test of medium speed diesel engine turbocharger. Fuel nozzle of combustor was designed and performed by PIV and PDPA test equipment. Through these results, spray characteristics were studied and flow coefficient equation was deduced.

• The KSFM Journal of Fluid Machinery
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• v.13 no.6
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• pp.19-24
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• 2010

The demands for small, high performance and high loaded aircraft compressor are increased in the world. But the design requirements become increasingly complex to design these high technical engines, the requirement of the design optimization become increased. The optimal design result of several disciplines show different tendencies and nonlinear characteristics of the compressor design, the multidisciplinary design optimization method must be considered in compressor design. Therefore, the artificial Neural Net method is adapted to make the approximation model of 3-stage axial compressor design optimization for considering the nonlinear characteristic. At last, the optimal result of this study is compared to that of previous study.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.05a
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• pp.713-718
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• 2003

The common practice to reduce the compressor noise is installing a muffler. The noise reduction performance of the muffler is the most critical one for the total noise characteristics of the compressor. In this paper, a simple impedance approach using the concept of transmissibility is employed for the acoustic analysis of the muffler, It is known that transmissibility is directly related to insertion loss, and thus transmissibility can Indicate the correct performance of the muffler. The analysis result is supported by a Finite Element Model. In addition, some experiments conducted also show that the transmissibility is mildly related to the measured sound pressure outside the compressor.

• Journal of the Korean Society of Propulsion Engineers
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• v.12 no.4
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• pp.56-62
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• 2008

This study presents the aerodynamic design and numerical analysis results on a transonic centrifugal compressor which is used for gas turbine systems. Mean-line analysis and quasi-3D analysis are used for the aerodynamic design, and Reynolds-averaged Navier-Stokes analysis is applied to flow analysis of the compressor. The aerodynamic parameters for a transonic compressor, such as pressure coefficient, swirl parameter, blade loading, are discussed, and flow characteristics in the impeller and diffuser are discussed.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1997.10a
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• pp.196-201
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• 1997

In point of noise and vibration, it is easy to occur a noise and vibration, because the reciprocal compressor is composed of crank shaft, rod piston and etc. Therefore, it is important to understand the mechanism of reciprocal compressor. In this study, we measured the sound pressure level of compressor. There are two dominent frequencies. The first of one results from the suction part. In suction process, the suction valve flutteres, and it produces the noise of the first frequency. The other results from the structural vibration of the shell resonated by discharge pipe. Thus, to reduce the noise of compressor, it will be most efficiency to redesign muffler for the first frequency and discharge pipe for the second frequency.

• The Journal of the Korea institute of electronic communication sciences
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• v.17 no.1
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• pp.173-180
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• 2022

Approximate Computing is a promising method for designing hardware-efficient computing systems. Approximate multiplication is one of key operations used in approximate computing methods for high performance and low power computing. An approximate 4-2 compressor can implement hardware-efficient circuits for approximate multiplication. In this paper, we propose an approximate multiplier with low area and low power characteristics. The proposed approximate multiplier architecture is segmented into three portions; an exact region, an approximate region, and a constant correction region. Partial product reduction in the approximation region are simplified using a new 4:2 approximate compressor, and the error due to approximation is compensated using a simple error correction scheme. Constant correction region uses a constant calculated with probabilistic analysis for reducing error. Experimental results of 8×8 multiplier show that the proposed design requires less area, and consumes less power than conventional 4-2 compressor-based approximate multiplier.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.25 no.12
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• pp.1721-1729
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• 2001

The performance of gas turbines is decreased as their operating hours increase. Fouling in the axial compressor is one of main reasons for the performance degradation of gas turbine. Airborne particles entering with air at the inlet into compressor adhere to the blade surface and result in the change of the blade shape, which is closely and sensitively related to the compressor performance. It is difficult to exactly analyze the mechanism of the compressor fouling because the growing process of the fouling is very slow and the dimension of the fouled depth on the blade surface is very small compared with blade dimensions. In this study, an improved analytic method to predict the motion of particles in compressor cascades and their deposition onto blade is proposed. Simulations using proposed method and their comparison with field data demonstrate the feasibility of the model. It if found that some important parameters such as chord length, solidity and number of stages, which represent the characteristics of compressor geometry, are closely related to the fouling phenomena. And, the particle sloe and patterns of their distributions are also Important factors to predict the fouling phenomena in the axial compressor of the gas turbine.

• Proceedings of the KSME Conference
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• 2007.05b
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• pp.2823-2828
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• 2007

Numerical simulation on the two-stage centrifugal compressor with Low Solidity Vaned Diffuser LSVD) for HFC-134a Turbo-chiller was performed using a commercial code. The comparative study with experimental results from other compressor was also investigated to testify the simulation schemes. The numerical analysis was separately simulated for each stage of the compressor and the effect of impeller-diffuser flow interaction was considered. Setting angle of the diffuser vane changed in the range of 15 deg. and the effects on its variation were discussed in detail including the flow analysis in the passage of the compressor. The vane setting angle obtained from the preliminary design was slightly adjusted to the optimal value by the performance enhancement in terms of pressure recovery and flow characteristics.