# Vol 17, No 4 (2018)

**Year:**2018**Articles:**15**URL:**https://journals.ssau.ru/vestnik/issue/view/305

## Full Issue

## AIRCRAFT AND SPACE ROCKET ENGINEERING

### Automated construction of a fan blade model according to data of CAD profile measurements

#### Abstract

The principle of automated construction of a fan blade model according to the profile measurements performed in a CAD-system is presented. Automatic construction of the model is based on the results of measurements obtained in the course of the control measurement procedure. The process of the blade airfoil control with the use of a portal-type Coord3 Hera NT coordinate-measuring machine and a measuring head with a Renishaw PH10T probe is described. The main points of the check method and instrumentation measures are presented. For example, the principle of the fan blade fixing is considered, the process of measuring the position of the base surfaces and points is presented, the process of measuring the profile points’ coordinates is described, the geometric parameters obtained in the course of calculation of profile deviations are presented. A measured 3D model of the fan blade is created according to the data of the control measurement procedure, taking into account complementary construction tools. The order of work for the automation of constructing a three-dimensional blade model is described. The direction of further work is specified, related to carrying out strength calculations to create a “hot” model of the measured blade, and subsequent aerodynamic calculations of the resulting blade to determine the most efficient set of geometric parameters for robust optimization.

**VESTNIK of Samara University. Aerospace and Mechanical Engineering**. 2018;17(4):7-17

### Analysis of control programs and flight paths of a hypersonic vehicle in climb

#### Abstract

Control programs and flight paths of a hypersonic vehicle in climb are analyzed. Two approaches to solving the task of determining the control programs and flight paths are identified: the “traditional” approach and the “optimization” one. The “traditional” approach implies specifying a typical mission profile of a hypersonic vehicle. In order to maximize the specific impulse (optimize the performance of the propulsion system) the vehicle moves along the line of peak dynamic pressing. In the case of the “optimization” approach the minimum fuel problem is stated and solved using the method of Pontryagin’s maximum principle. It concerns the mass of fuel consumed in hypersonic acceleration. Optimal control programs and optimal flight paths are determined. The results of modeling the motion of a hypersonic vehicle with angle-of-attack schedules corresponding to the “traditional” and “optimization” approaches are presented and discussed. It is established that less fuel is consumed in the case of optimal control, which is accounted for by more efficient use of the hypersonic vehicle aerodynamic performance due to direct control of the angle of attack.

**VESTNIK of Samara University. Aerospace and Mechanical Engineering**. 2018;17(4):18-26

### Construction of limitation diagrams for truss core stiffness and strength parameters

#### Abstract

A truss-core sandwich panel is a promising load-bearing element of lightweight high-stiffness structures. The use of this element in load-bearing structures makes it necessary to know its mechanical and strength characteristics depending on the structure and properties of a typical core cell. Currently, the available results are not sufficient to assess the strength due to the complexity of taking into account all the features of the loading of the core structure in the form of repeated pyramidal and tetrahedral unit cells most common in the production of lightweight truss cores. In the research of the strength properties of a unit cell, it is assumed that the destruction of the truss structure may occur when the yield stress in the material of the core is exceeded or if buckling takes place. The scheme of destruction of the truss structure in the cell will depend on the combination of unit cell equivalent stress values. The critical core buckling stress is usually less than the yield stress. Therefore, when co block diagrams of equivalent stress constraints are constructed, one can observe a rather complex picture of the change in the limit values depending on the azimuthal angle in the plane of the cell base. To analyze limitation diagrams, the easiest way is to introduce a parameter determined by the ratio of the critical buckling stress to the magnitude of the yield stress of the core material. In this case the limitation diagrams will not depend on the specific critical absolute values of stresses, but on their relationship; the nature of the diagrams will not depend on the density of the core. The design parameters of the core are determined on the basis of the construction of other diagrams for the given (required) values of generalized compressive stiffness, transverse shear, generalized critical compressive stresses and transverse shear of a unit cell of the sandwich structure which depend on the relative density of the truss core. The combination of these two constraint diagrams gives a more complete picture of the degree of optimality of the truss core design parameters.

**VESTNIK of Samara University. Aerospace and Mechanical Engineering**. 2018;17(4):27-36

### Theory and calculation of parameters of the detonation engine thermodynamical cycle

#### Abstract

The ideal thermodynamic cycle of a detonation engine is substantiated and a method of computing the engine parameters is presented. In the ideal cycle the processes of gas compression and expansion are adiabatic. It is shown that low thermodynamic effectiveness of the detonation engine can be explained by significant wave losses of the total pressure in the shock wave and the entropy increase. The advantage of the engine in comparison with other thermal machines is the capability of obtaining a high value of absolute energy of the gas flow to do the work of gas expansion. While analyzing the thermodynamic cycle it is assumed, like in the gas turbine engine theory, that the characteristics of gas condition are determined by the parameters of stagnation subsonic flow in the sections corresponding to the beginning and the end of the processes making up the cycle. Heat supply downstream of the shock wave takes place in the subsonic flow in a constant-pressure process. Consideration of the cycle with stagnation parameters significantly simplifies its analysis and gives a fuller picture of its energy. A formula for calculating the coefficient of thermal efficiency of the ideal cycle of a detonation engine is presented as a function of the specific speed of propagation of the stabilized shock wave. It is shown that the ideal thermodynamic cycle of a detonation engine is described by two adiabatic curves, an isothermal curve determining huge wave losses, and two isobaric curves. The work of gas expansion in a detonation engine can be implemented both for obtaining the moving force of a vehicle and in industry, e. g., for metal hardening and cutting, production of high-hardness artificial diamonds, geophysical investigation.

**VESTNIK of Samara University. Aerospace and Mechanical Engineering**. 2018;17(4):37-46

### Оptimization of gas turbine aircraft engine control throughout the engine service life

#### Abstract

The task of optimizing control methods in order to maintain key performance parameters of a gas turbine engine throughout the engine service life is considered. Variations in the performance characteristics of engine components in the process of operation are analyzed. To study the effect of deterioration on the engine parameters, a mathematical model of a turbofan engine was modified. The influence of degradation of the gas turbine engine components on its key performance parameters with traditional control methods is assessed. An engine control method using the value of thrust calculated in the on-board engine mathematical model is proposed. This method makes it possible to compensate for the negative effect of the components’ performance degradation due to their wear. The results of mathematical modeling of the operation of a turbofan engine in steady-state and transient modes are given. The results confirm the effectiveness of the proposed control method: despite the engine deterioration the original thrust value is maintained due to the available gas temperature margin in the combustion chamber

**VESTNIK of Samara University. Aerospace and Mechanical Engineering**. 2018;17(4):47-56

### Development of methods for ensuring energy balance for the operation of mission equipment of “AIST”-series small satellites under conditions of power limitations

#### Abstract

The article examines the issues of determining the light-and-shadow situation and its impact on providing energy balance on the orbits of two small satellites of the “AIST” series. Ensuring energy balance in the operation of mission equipment becomes particularly relevant in the case of power limitations caused by both the degradation of spacecraft systems and the factors of outer space. The main purpose of the article is to solve the problem of increasing the efficiency of the power supply system of “AIST”-series small satellites operating under resource constraints. Firstly, modeling of the lighting situation on the orbits of small satellites was carried out. Secondly, the telemetric information of “AIST” small satellites for the whole period of operation was examined. In addition, the influence of the light-and-shadow conditions on the parameters of the power system of a small satellite was analyzed. As a result, an algorithm for estimating the energy balance, taking into account the influence of the light-and-shadow situation was proposed. Using the proposed algorithm made it possible to take into account the influence of seasonal variations in the light-and-shadow environment on the possibility of ensuring energy balance in the operation of mission equipment

**VESTNIK of Samara University. Aerospace and Mechanical Engineering**. 2018;17(4):57-66

### Programs of time-optimal control in the problem of rendezvous transfer of spacecraft with low transversal thrust

#### Abstract

We study the problem of determining time-optimal control of in-plane rendezvous transfer of spacecraft with low transversal thrust. We use the Pontryagin maximum principle to determine the optimal control program. Motion is considered in the vehicle centric system with linearized equations. We recognize secular and periodic components of relative motion. Motion control is accomplished by the reversal of the thrust acceleration component. We study the general problem – controlling the periodic and secular components at the same time (joint optimal control program). Also we study partial problems – determining separate control programs for secular and periodic components of planar motion. Solving partial problems made it possible to determine the structure of the joint optimal control program. We found that the adjustment of secular motion components contains no more than two phases of constant acceleration. The adjustment of periodic motion components consists of a sequence of boost and deceleration phases, the number of which in a single pass does not exceed three.

**VESTNIK of Samara University. Aerospace and Mechanical Engineering**. 2018;17(4):67-80

### Proposals for improving the efficiency and service life of the turbines of turbo-pump assemblies in liquid-propellant rocket engines by using double-sided crest-type radial labyrinth seals

#### Abstract

Nowadays the improvement of the design of liquid-propellant rocket engines (LPREs) depends on a variety of factors and activities, among which we can distinguish, for example, the improvement of energy characteristics of units and assemblies forming part of the LPREs. The article compares the operation of LPRE turbo-pump turbines using double-sided and single-sided labyrinth seals used in Energomash's engines. The key geometrical parameters of each seal variant, images of 3D-models of seals constructed for the calculations, the resulting computational grid for each seal variant, as well as graphs of the pressure distribution and velocity fields are presented for visual comparison. Sectoral leakage was calculated for each variant of the seal, the possibility of reducing the temperature of the turbine inlet working gas was assessed. In the future attention should be paid to a more detailed study of this type of seals with the use of modern computing power

**VESTNIK of Samara University. Aerospace and Mechanical Engineering**. 2018;17(4):81-92

### Optimization of fuel distribution in the afterburner of a gas turbine engine

#### Abstract

The use of 3-D simulation programs and in particular NX and ANSYS simulators brought the design and fine tuning of gas turbine engine combustion chambers to the next level, as it allows improving the performance (increased combustion efficiency, reduced radial and circumferential non-uniformity of the total gas temperature), as well as determining the weak points of the structure. The article analyzes the flow of fuel jets from the finger sprayers of the afterburner of the combustion chamber of a gas turbine engine. The problem of optimizing the distribution of fuel is formulated: the fuel at the exit of the flame tube is to be evenly distributed by varying the diameters of the holes in the fuel manifolds. Restrictions are imposed on the optimization problem – the supply of fuel to the peripheral zone at the outlet of the afterburner is reduced by a factor of five. The optimization effect is verified by comparing the fuel combustion efficiency in the case of standard fuel distribution with the optimized distribution option using the NX and ANSYS 3-D simulations. As a result, we observe an increase in combustion efficiency in all afterburner modes of engine operation.

**VESTNIK of Samara University. Aerospace and Mechanical Engineering**. 2018;17(4):93-101

### Impact of the turbulence modeling approach on the accuracy of the fan noise level prediction

#### Abstract

The fan is the dominant source of noise for modern high bypass ratio aircraft engines. The article presents the results of investigating the influence of the approach to modeling the turbulence in modeling fan stage noise generation on the results of noise level prediction. Numerical investigation was performed for a model fan stage in test conditions in an anechoic chamber. Basic operating modes determining the acoustic performance of the fan were used. Calculation of far-field noise was performed using finite element modeling on the basis of the modal composition of generated noise. The influence of the turbulence model on the number and amplitude of acoustic modes excited in the flow on the fundamental frequency harmonics was analyzed. It is shown that modeling of the anisotropic flow turbulence in calculating non-stationary rotor-stator interaction makes it possible to obtain results close to the experimental ones.

**VESTNIK of Samara University. Aerospace and Mechanical Engineering**. 2018;17(4):102-114

### Propulsion systems and low-thrust rocket engines based on various physical principles for control systems of small and micro-spacecraft

#### Abstract

The article presents an analysis of the possibility of using propulsion systems and rocket thrusters based on various physical principles and used as part of small and very small spacecraft. The parameters of efficient propulsion systems and low-thrust rocket engines are examined from the standpoint of being used as components of spacecraft fueled by various kinds of propellant: gaseous fuel, mono-fuel, including advanced compositions based on hydroxyl-ammonium nitrate, bipropellant fuel; xenon electric rocket systems, as well as special propulsion systems and low-thrust rocket engines operating on nitrous oxide, ammonia, gaseous hydrogen and oxygen; electric-powered systems based on pulsed plasma thrusters, ion and steady-state plasma engines. Taking into account the data analyzed, an attempt was made to categorize the propulsion systems and low-thrust rocket engines. Their use in small spacecraft, spacecraft of the “Mini”, “Micro”, “Nano” classes in various propulsion systems and low-thrust rocket engines was found to be preferable.

**VESTNIK of Samara University. Aerospace and Mechanical Engineering**. 2018;17(4):115-128

### Experimental research on the development of an “oxygen (gas) + kerosene” – fueled thruster

#### Abstract

The results of experimental studies of a rocket engine fueled by gaseous oxygen-kerosene with a thrust of 20N, with four workflow variants are presented. The first version of the engine with the UVK-1 chamber demonstrated low energy characteristics, there were misfires. The engine with the UVK-2 chamber differed from the UVK-1 in that the fuel injector had a large geometric characteristic due to the increased diameter of its nozzle. The UVK2 provided stable start without misfiring and slightly improved energy characteristics. In the UVK-3 version, the energy characteristics were improved by decreasing the proportion of the oxidizer supplied to the curtain of internal cooling. The increase in the length of the cylindrical part of the combustion chamber (variant UVK-4) did not lead to the expected increase in energy characteristics. This is probably due to the peculiarity of the location of the cooling curtain assembly. In the course of research it was also found that the parameters of the igniter electric discharge have a significant influence on the nature of the chamber working process during the starting period. It is expedient to search for ways of further improving the energy characteristics in the direction of reducing the oxygen flow to the cooling curtain in the UVK-3 version with the nozzle material replaced by Nb5V2MC.

**VESTNIK of Samara University. Aerospace and Mechanical Engineering**. 2018;17(4):129-140

### Numerical simulation of low liquid flow in a mixer consisting of two centrifugal swirlers

#### Abstract

The paper describes a procedure of numerical simulation of operating fluid (water) discharge into the air environment through the hydraulic paths of a mixer composed of two low-flow coaxial swirl injectors. The method is based on a two-velocity model of a two-phase liquid flow and determining the interface interaction resistance coefficient versus the Reynolds number in the course of solution. The Reynolds number is calculated from the relative velocity of the liquid components forming the two-phase flow. The paper investigates variations in the mixer spray pattern versus two characteristic dimensions reckoned among the key parameters to calculate the coefficient of interface interaction resistance. Algorithms of calculating the coefficient of interface interaction resistance are proposed. The results of modeling liquid mixing and film flow breakdown within and beyond the mixer hydraulic paths for different values of the characteristic dimensions are presented. It is shown that we can achieve the conformity of the calculation results obtained by using the proposed method with the cold flow data by selecting the values of characteristic dimensions with reference to which interface interaction resistance coefficients are determined. Further works are projected.

**VESTNIK of Samara University. Aerospace and Mechanical Engineering**. 2018;17(4):141-154

### Comparative analysis of fuel distribution downstream of the gas-dynamic flame holder with various methods of injection

#### Abstract

The article deals with the problems of atomization and distribution of liquid fuel in a swirling flow downstream of the front-end gas-dynamic stabilizer designed for the use in gas turbine engine combustion chambers. The task is to compare the distributions of droplet-liquid fuel in the wake of the stabilizer when the fuel is injected from the side and end surfaces of the device in question. It is shown that the calculations performed according to a stationary model are qualitatively different from the non-stationary ones in both fuel supply options. However, in the first approximation, the distributions of liquid droplet fuel fed from the side and end surfaces of the stabilizer are similar. An experimental study of the spray characteristics was conducted by the Shadowgraphy method of diagnosing droplet-air fluxes with the fuel supplied at an azimuthal angle of 45° from the side surface of the gas-dynamic stabilizer. It is shown that if the fuel is injected at an angle it leads to a change in the velocity distribution in the wake of the stabilizer, and the flow swirl opposite to direction of azimuth fuel supply expands the spray pattern.

**VESTNIK of Samara University. Aerospace and Mechanical Engineering**. 2018;17(4):155-164

## MECHANICAL ENGINEERING

### Process of coating the inner surface of an inclined pipe and its mathematical modeling

#### Abstract

A new method is proposed for coating the inner surface of pipes in a confined space in which a sloping position of the pipe is expected during the process. Mathematical modeling of non-pressure fluid flow in an inclined pipe was carried out. The method implies controlled outflow of the material being applied and simultaneous rotation of the pipe being worked. The thickness of the coating depends on the velocity of the material flow along the inner surface of the pipe. The dependence of the fluid velocity on the radius of the pipe being worked and the level height in the filling column is calculated. The results of calculating the analytical dependence in the Mathcad application are presented. Dependence diagrams of material flow are presented for various design parameters that make it possible to determine the operating practices in the process of applying the coating. Uniform coating is obtained due to constant velocity of the material flow along the full length of the pipe. The obtained graphs were analyzed and the direction of further research connected with the influence of rotational velocity and fluid viscosity was determined. The use of the proposed method makes it possible to increase labor productivity and improve the quality of protective coating.

**VESTNIK of Samara University. Aerospace and Mechanical Engineering**. 2018;17(4):165-172