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.
Performance Analysis of OIF Single Screw Compressor
This paper presents the performance analysis and the internal pressure measurement of the oil injectionfree single screw compressor. The geometric shape of the single screw compressor and its theoretical performance with the slide valve have been analyzed. The internal pressure has been measured with piezo type pressure sensors, and the pressure-volume diagram has been obtained. The experimental results agree fairly well with the theoretical predictions, and the volumetric and adiabatic efficiency can be estimated by this analysis. SYMBOLS A cross sectional area Dsg distance between screw axis and gate rotor axis F coefficient of flow rate Gc mass of gas in the groove G· l mass of gas which enters the groove Go mass of gas which comes out of the groove
Numerical Simulation of Thermal Sensitivity for Explosives
In order to compare the thermal sensitivity of several typical explosives, this article solved numerically one-dimensional transient heat conduction equation including thermal decomposition for explosives with finite difference method. The explicit difference equations under different boundary conditions were established, and the corresponding stability criterion was derived. The ignition times for typical explosives were calculated, which was used to evaluate thermal sensitivity of explosives.