Experimental research of incipient turbulent flow frequency spectra in hydrodynamic unsteadiness

Hydraulic and heat transfer processes play a very important role in the design and prototyping of aerospace technology. Unsteady conditions are the peculiarity of mostly aerospace systems. Flow acceleration and deceleration may significantly affect the heat transfer and hydrodynamic process in channels of aerospace systems. For unsteady process modeling, a fundamental research of unsteady hydrodynamic turbulent flow structure., Moscow Aviation Institute National Research University (MAI) has been building unsteady turbulent flow structures since 1989. An experimental facility was designed to provide gas flow acceleration and deceleration. Experimental data of a turbulent gas flow structure during flow acceleration and flow deceleration are presented. The frequency spectra of axial and radial velocity pulsations are based on experimental data. The results of experimental turbulent flow research demonstrate the fundamental hydrodynamic unsteadiness influence on the flow structure. The main results of the flow acceleration and deceleration experimental research show that there are tangible differences from the steady flow structure. The analysis of unsteady conditions influence on the turbulent pulsations generation and development mechanisms is presented. The results show the unsteady conditions influence onto turbulent vortexes disintegration tempo. The present paper describes a method of experimental research, methodology of data processing and turbulent accelerated and decelerated flow spectra results.

DEVELOPMENT OF A NON-STATIONARY MATHEMATICAL MODEL FOR THE PROCESS OF POLYMERIZATION OF PROPYLENE

The mathematical model has been developed for the process polymerization propylene proceeding under unsteady conditions due to the toxic effect of methylacetylene on it, leading to decrease of the productivity and quality of polypropylene. Non-stationary function to maintain the productivity at the optimum level obtained during the process in stationary conditions has been proposed. Using this mathematical model allow ones control the process, stabilize it at any time of the polymerization operation. The control scheme of algorithm of this process has been created

Multi-Physics Dynamic Modeling and Transient Simulation of a Multi-Stage Heat Recovery Steam Generator (HRSG)

This paper presents a dynamic model of a three-pressure-stage Heat Recovery Steam Generator (HRSG) system. It is developed on the Siemens T3000 plant monitoring environment. The multi-physics mathematical model captures essential physical phenomena of the HRSG system such as thermodynamics, heat transfer, phase change, fluid dynamics, etc. as well as their couplings. Fast simulation of the dynamic model is achieved and real-time execution is feasible. Aside from heat exchange elements such as economizers and superheaters, the critical components of the model are the high, intermediate, and low pressure boilers. Here, phase transitions and widely different operating pressures pose unique computational challenges and demand accurate modeling of mass and energy balance during unsteady conditions. A two-mode dynamics has been implemented in modeling the boilers. The model switches between these modes during transients. Through collaboration with Siemens Energy Inc., the model’s transient behavior and steady values have been validated with selected transient startup-data from a real HRSG.