Aircraft Engine units
The turbofan engine consists of four structural units, which formed the basis for the following separate research areas in CIAM:
- Fans and compressors;
- Combustion chambers;
- Nozzles and air intakes.
The engineers of the department conduct experimental studies at CIAM's test facility. This unique facility enables studies using models and single-burner sections of combustion chambers at the maximum combustion chamber pressure of 50 bar and maximum air temperature of 1000 K (provided by electric heaters).
Fans and Compressors
Even in the pre-World War II era, CIAM had accumulated great experience in designing reciprocating engine supercharger compressors. V. Dmitriyevsky and K. Kholschevnikov (one of the impeller machine theory inventors) had been working successfully in this area. In 1941, studies in the compressor aerodynamics area were concentrated at a specialized laboratory established on the basis of the high altitude equipment laboratory which later was transformed into the Institute department.
The significance of work in this area cannot be overestimated. Now that leading aircraft engine manufacturers strive for every tenth of a percentage point of fuel and weight efficiency, increasing the efficiency of fan and compressor stages becomes one of the necessary conditions for competitive product design. Fan noise reduction is a critical matter too, since environmental standards has become one of the main factors determining the development of the world's engine industry.
One of the most remarkable achievements of CIAM in the beginning of the 21st century, emphasizing CIAM leadership, is the development of the theoretical and practical basis for designing a new impeller machine generation. Computer-aided modeling based on 4D mathematical models of unsteady turbulent flows - an excellent tool, which became available to researchers recently, contributed to a breakthrough in aircraft engine design. The most tangible results of the practical implementation of this breakthrough were obtained in the field of impeller machine design. Design reliability and quality was enhanced and the time of axial and centrifugal compressor refinement was reduced.
The most important requirement to high-speed aircraft engines is thrust increase. Regardless the achieved capacity of centrifugal compressors increase, a drastic increase of capacity became possible with the use of axial compressors only, which constitutes a considerable part of the studies. The core matter of the steady-state aerodynamics of axial compressor stages is the development of highly efficient, high-pressure stages and few-stage axial compressors. This matter deals with the reasonable selection of aerodynamic load and tip speed, as well as (and even more importantly) with the application of advanced design technology.
The design and refinement of efficient high-pressure axial, centrifugal, and axial-centrifugal compressors rely heavily on the new technologies.
The CIAM engineers develop and conduct experimental studies of typical high load highly efficient axial stages of fans, low and high pressure compressors of future gas turbine engines in a wide range of change of the stage parameters.
The Institute’s engineers design multi-stage compressors for various purposes using 1D and 2D flow models, refine and optimize the compressors utilizing direct and reverse viscous 3D flow models, and conduct the compressors testing.
The Institute's researchers develop procedures for providing the desired performance of stages and multi-stage compressors by mean of using shroud devices and other control equipment in adverse flow areas.
CIAM carries out efforts on enhancement of direct and reverse calculated flow models using RANS and URANS approximations, also with regard to unsteady interaction of blade rings, using the NLH method, both for solvihg gas dynamics and aeroacoustics issues.
CIAM develops centrifugal stages in a wide range of parameters, for W = 0.015…15kg/s; PR = 3…12; RPM = 30,000…70,000.
Institute engineers design centrifugal compressors using 1D and 2D methods and design experience aggregated data, with the evaluation of static and dynamic blade stresses. Stage flow optimization performs utilizing 3D viscous gas models. Design results are verified during the experimental studies conducted to determine flow parameters in representative cross sections and total stage performance.
Institute researchers study new types of axial and centrifugal stages and multi-stage GTE compressors in order to compare design cycle parameters with actual results obtained at test rigs and to determine real stall margins. Measures affecting on flow in airfoils are investigated and recommendations concerning the use of them in multi-stage compressors are provided.
The test rig infrastructure allows to conduct experimental studies involving measurements of both the static and dynamic flow parameters, such as pressures, speeds, flow directions, while also monitoring stresses, temperatures, and vibrations of the structural elements of test items.
Experimental refinement of noise suppression systems of aircraft engines comprises multiple stages.
The approximate setup of a silencer sample, sound absorption coefficient and impedance in conditions of normal sound incidence on the silencer surface are determined by using an Interferometer laboratory rig.
The amount of fan noise reduction resulting from reduction the tested silencer installation of in the model is determined by dual reverberation chamber rig.
Turbofan duct silencer components and fan noise systems, installed in the nacelle are refined using a test cell with a large anechoic chamber.
The final check of noise reduction system efficiency is conducted using a full-scale engine demonstrator at an open test cell.
The efficiency of future fan noise suppression systems is verified using model fans with a diameter of 400–700 mm.
A turbine is a gas turbine engine assembly operating in the most difficult loading conditions. Turbine design has always been the key engineering task of gas turbine engine development. The turbine is a component intervining issues of strength, gas dynamics, and materials science. In the USSR, efforts on gas turbine engine development had begun before World War II on the initiative of V. Uvarov, the founder of the Russian gas turbine engine development school. In 1940, Uvarov's group was transferred to CIAM. However, active research in this field only began after World War II. The works on turbine research were conducted by various Institute divisions in two areas - gas dynamics and thermal design. In 1970, these divisions were aggregated in an independent gas turbine department.
The convection film cooling blade manufacture technology, the key technology of 4th generation engines, was implemented in the 1970s with CIAM's participation. The main trends in the development of aircraft GTE turbines are are turbine inlet gas temperature, design simplification, and number of parts (stages, blades) reduction, ensuring maximum efficiency in the principal conditions, long service life and high reliability. CIAM experts conduct work in the relevant areas of turbine gas dynamics; special departments solve top priority thermal, design, and process problems that occur in the development of highly efficient designs and processes of aircraft GTE turbines. By the present time, the gas turbine department has established an advance a foundation that enables the development of 5th generation aircraft engine turbines operating under extremely high temperatures. Besides that, efforts of meeting long term goals are also underway.
The combustion chambers of aircraft gas turbine engines are the devices that to the maximum extend define the perfection of the aircraft. The development of modern combustion chambers of aircraft engines requires patient research of optimal designs and their extensive experimental refinement. The creation of low-emission combustion chambers is the key technology determining the economic and environmental performance of present-day gas turbine engines. The combustion chamber department was established in CIAM on 1948 and was headed by Institute Director T. Melkumov. Since then, this department has been among the industry leaders. The main areas of studies of combustion chambers have been determined by the current trends in the development of new gas turbine engines with enhanced thermal and dynamic performance and operating envelope, technical and environmental characteristics.
Nozzles and Air Intakes
Creating a research and technical advance foundation for providing the aerodynamics of the flow path components of power plants and future engines for various purpose aircraft is one of the primary areas of CIAM activities.
Along with other Institute divisions, the Gas Dynamics Laboratory, established in 1952, carries out calculation and experimental studies of air intakes and nozzles. Its first scientific director was a young engineer who had become academician - G. Cherny, the founder of an internationally recognized scientific school of gas dynamics. The physical laws identified by CIAM researchers, the standard dependence of the total pressure recovery factor of air intakes on the flight Mach number, have become fundamental for the engine industry.
Institute researchers study new methods of gas flows mathematical modeling, create optimal shaping methods, develop and validate models of active flow control devices. The resulting approaches are used to develop the concept design and investigate the performance of inlet and outlet devices and to enhance the aerodynamics of future engine internal channels to ensure their high performance.
Since jet noise is main source of an acoustic environmental impact of a GTE, silencing nozzle studies are the most important areas of the Institute's activities, directly determining the competitive of existing and future Russian aircraft engines in the context of increasingly strict international environmental requirements.
CIAM's experimental infrastructure enables testing of full-scale power plants assembled with an air intake, including tests that simulate engine intake flow irregularity.