This study is an attempt to determine if there is any speed sensitive phenomenon in flapper valve operation. Valve motion is measured at various speeds in a reciprocating residential refrigerator/freezer compressor. Laser Doppler Velocimetry is used to measure the velocity of a point on the flapper at the center of the port for the suction valve. This velocity data is numerically integrated to ...

A computational study of compressor instability based on body force representation of each blade-row of a transonic stage has been implemented for both clean inlet flow and flow with circumferential total pressure inlet distortion. The computational results indicate that many aspects related to compressor instability differ from what was observed in the experiment: steady compressor characteris...

As it has been already proved, link layer compression is very effective when used in packet networks. However one of the major problems in such compression schemes, is that there should exist hardware modules capable of compressing the network streams up to the speed of the state-of-theart links. In this paper we present such a hardware compressor/decompressor that can work up to these speeds, ...

Flow losses through the valve ports contribute a significant portion to the total energy loss of a high speed compressor. As a result, in the energyconscious world of today, compressor designers are always busy finding methods and techniques to minimize these losses. It can be argued that the various fundamentally different compressor concepts would have different valve flow losses simply as a ...

This thesis contains new results in the eld of modeling and control of rotating stall and surge in compressors. A close coupled valve is included in the Moore-Greitzer compression system model and controllers for both surge and rotating stall is derived using backstepping. Disturbances, constant and time varying, are then taken into account, and nonlinear controllers are derived. Stability resu...

The last decade has seen an increasing awareness that the manner by which a compressor meets the part load conditions of residential air conditioning is a strong dete:cninant of the a.easonal SEER of the air conditioner. The compressor can reSPond to part load needs by cycling if of the single SPeed variety, by cycling between capacity levels if of the multiSPeed variety, by use of internal cap...

There are different technologies to adapt the compressor’s cooling capacity to the changing requirements of the A/C and refrigerant systems when operating with screw compressors. • Distribution of the requirements to several compressors (parallel operation) • Evaporation pressure control with hot gas bypass • Internal bypass in the compressor • Reduction of the compressor displacement by a cont...

Centrifugal compressors are used in a large number of different compression applications. This tutorial addresses applications for centrifugal compressors in the upstream and midstream sector, such as LNG compression, refrigeration, pipeline compression, compression for gas injection, gas lift, gas gathering, export compression, air compression, and others. The focus is on the specific compress...

Generation of coherent short-wavelength radiation across a plasma column is dramatically improved under traveling-wave excitation (TWE). The latter is optimized when its propagation is close to the speed of light, which implies small-angle target-irradiation. Yet, short-wavelength lasing needs large irradiation angles in order to increase the optical penetration of the pump into the plasma core...

SUMMARY The aerodynamic design and experimental performance of a centrifugal compressor designed for a pressure ratio of 6.5 and a specific speed of 68 are described, The compressor consisted of a radially-vaned impeller and a transonic, vaned radial diffuser. At design speed a peak overall total-to-total isentropic efficiency of 0.746 was achieved at the maximum pressure ratio of 5.9, rising t...