Research Activity
The main scientific directions that are developed by the Academic staff of the department are:
- Heating, air conditioning and gas supply systems;
- Systems with renewable energy sources;
- Fluid mechanics, heat and mass transfer;
- Research and increase the energy performance of hydro and pneumatic machines;
- Hydro and pneumatic drive systems;
- Ecology and protection of ecosystems;
- Theory and risk management;
- Environmental and production safety;
- Environmental protection;
The Centre for Risk Engineering and Risk Management operates under the direction "Ecology and Environmental Protection". Its purpose is to develop the protection of the security of the population, the environment, the national economy and resources, corporate and labor safety, infrastructure, including the implementation of the best European and global practices in risk management.
- Over the years, a number of researches in the field of hydraulic and pneumatic technology and related applied hydromechanics have been carried out in the Department of Technical Engineering. These studies can be grouped into the following main sub-directions:
Investigation of turbomachinery (pumps, hydro fans and wind turbines)
A methodology, an experimental arrangement was developed and balance studies of multi-stage centrifugal pumps were carried out. The influence of the guide and return devices on the energy indicators of these pumps was studied - protected 1 dissertation.
A methodology was developed and the influence of the undercutting of the impellers of centrifugal pumps with different specific rotation frequency was investigated.
A methodology and experimental setup for the study of centrifugal pumps when working with a water-air mixture has been developed - protected 1 dissertation.
An experimental arrangement was developed and the influence of the number and geometry of the blades of the impellers of low-flow centrifugal pumps was studied - the subject of 1 doctoral study.
An experimental device and a micro water turbine were developed to study the influence of the regulating body of a radial-axis turbine - subject of 1 doctoral study.
Development and research of variants of hybrid windmills with a vertical axis of rotation - training of 1 full-time doctoral student.
Investigations of volumetric hydraulic machines
Rotary piston pumps designed for the transport of highly viscous liquids have been developed and extensively researched (theoretically and experimentally) - 2 dissertations and one habilitation for a professor have been defended.
A high-torque radial piston hydro-motor was developed and energy and research, as well as theoretical and experimental studies on the liquid distribution system (frontal distributor) were conducted - 1 dissertation was defended.
Plate pumps designed for working with water and aqueous solutions have been developed and studied - 1 dissertation has been defended.
Developed an experimental roller pump and an experimental device for studying the influence of the main design and mode parameters on the energy characteristics - subject of 1 doctoral study.
A plate vacuum pump has been developed and is being researched - the subject of 1 doctoral study.
A three-rotor toothed hydro machine has been developed which is protected by a patent. Theoretical and experimental research and the preparation of a dissertation work are carried out.
A set of test equipment has been created for axial-piston and other types of volumetric pumps and motors with a power of up to 75 kW, on which applied research and operational tests of hydraulic machines from the hydraulic drive systems of road construction, agricultural, etc. are carried out machines.
Gear pumps with asymmetric involute gearing have been created and are being tested for the needs of the company "Caproni" - the city of Kazanlak.
Energy efficiency of fluid transport systems
Models and criteria for evaluating the energy efficiency of pumping systems with centrifugal pumps have been compiled. An experimental device was developed to study the energy efficiency of the flow rate regulation methods of such systems - preparation of 1 full-time doctoral student.
Study of the energy efficiency of ventilator systems for fluid transport - preparation of 1 full-time doctoral student.
- Applied hydromechanics
Research of the phenomena and processes in hydraulic machines and systems is in many cases related to solving problems in the field of fluid mechanics. This led to the accumulation of experience in the use of methods and specificity in the study of fluid movements in various transfer technological processes, machines and equipment. Examples of such studies are given below. The processes during the movement of a water-air two-phase mixture through the flow part of turbomachines have been studied. The task of determining the distribution of pressure and velocities of the two phases in the impeller of a centrifugal pump depending on the volumetric concentration of the gas phase was solved. For this purpose, a two-fluid model of the flow in the impeller was created and its numerical implementation was supported by experimental studies conducted in one of the laboratories of the Department of Technical Engineering. The mathematical model was created based on Newton-type equations. A numerical procedure was developed in the MATLAB environment to solve the differential-algebraic system of equations of the model.
Another topic is the study of the force interaction between the flow through the sealing gap with a front distributor for a multi-stroke hydraulic motor. The problem of determining the pressure distribution and the flow through the front gap was solved. A flow model was created based on the Reynolds equation. The theoretical model is supported by experimental studies.
The department works in the field of research of hybrid windmills with a vertical axis of rotation of the Darius-Savonius type. The purpose of the study is to analyze the force interaction between the air stream and the impeller and to obtain its aerodynamic frequency and control characteristics. A methodology has been developed for modeling the current through the windmill based on CFD software product ANSYS. The method was verified by studying an impeller with one blade, and the results were compared with those of leading specialists in the field. An experimental setup for verifying the theoretical results has been designed and is being made.
One of the scientific topics that has been worked on in recent years in the department is the mathematical modeling and research of transferable technological processes from the chemical, biotechnological and food industries.
The hydrodynamic and heat exchange processes in a glass bath furnace for the production of flat glass according to the Pittsburgh system were investigated. A mathematical model of the hydrodynamic and heat exchange processes occurring in the bath of a glass bath furnace for the production of flat glass has been developed. Efficient numerical algorithms have been developed to solve the resulting boundary value problems for the model equations. Using the developed mathematical model and numerical technology, the operation of the furnace for the production of flat glass in the company "Diamant" AD - Razgrad was simulated. 1 dissertation has been defended.
The hydrodynamics and mass transfer processes in chemical reactors with mechanical stirring were investigated. A mathematical model of the movement of a viscous incompressible fluid in a cylindrical reactor under mechanical stirring was built based on the Navier-Stokes equations. First-order accuracy mathematical boundary conditions for the velocity vortex are proposed to close the boundary value problem. A numerical algorithm for solving the boundary value problem for the Navier-Stokes equations has been developed to study the hydrodynamics in a cylindrical mechanically stirred reactor. This algorithm is implemented in the MATLAB programming environment. 1 dissertation has been defended.
