Approach To The Numeric Geometry Analysis of Positive Displacement Compressors, Its Application To A Single Screw Compressor Simulation And Verification By Experiment
Thermodynamic models to simulate positive displacement compressors are well known for a few decades already and can describe the compressor performance quite well. One of the most complex part of the simulation process however is the positive displacement compressor geometry simulation. In the current context, under geometry simulation, values of working compressor volumes, as well as cross-sections of port openings, at different shaft (rotor) angles are considered. In the current paper, as an example, the Greene formula approach was applied to a geometry simulation of a single screw compressor. Working chamber geometry was defined by “cutting “ it with the gate rotor blade; flute volume was computed using Greene formula; suction and discharge ports were intersected with this volume so that port opening contours were defined and their respective cross sectional areas were calculated. The results of this geometry simulation were applied for a thermodynamic model of a single screw compressor. Experimental investigation of a single screw working process using pressure transducers has been conducted. Geometry simulation data was applied to calculate compression work from experimental pressure traces. Pressure-volume diagrams obtained experimentally were compared to the simulated ones. Also, indicator work obtained from simulation and experiment, was compared to the power input to the shaft, and demonstrated good correlation.
CUTTING TOOLS FOR GENERATING OF ROTORS COMPRESSORS
The compressor rotors usually are helical surfaces with constant pitch and are composed of crossing profiles. Frequently, for repair operations, the reconstruction necessity occurs for one or both of the worms, drive and driven, from the helical compressors gear. The theoretical helical surface of the worm is being substituted by an assembly of helical lines which together with crossing profiles forms points cloud resulted from measuring leads to a polyhedral expression of the flank rotor. Numerically, this surface type is expressed by a coordinate array which shows its discrete image. The profiling of cutting tool bounded by a revolution surface reciprocally enveloping with the substitutive surface of the helical one represents a special problem. In this paper is proposed an algorithm for polyhedral expression of the helical surface previously determined by reverse engineering methods and an algorithm for the determination of the specific enveloping condition at contact with a discrete surface. It is presented an example for a compressor rotor measured on a 3D measuring machine, the algorithm for the transformation of the gathered points cloud in a surface with polyhedral expression. Given these conditions there were determined the enveloping condition and the axial section of the side mill.
White-Collar Crime in Modern England: Financial Fraud and Business Morality, 1845-1929.
List of tables Acknowledgments Introduction 1. The new economy: transformation of finance and opportunities for crime 2. The railway mania 3. Banking and credit fraud 4. Stock fraud 5. Company fraud: promotion 6. Company fraud: management 7. Company law and the courts 8. Business ethics and professionalization Conclusion Notes Bibliography Index.