Experimental study of radial temperature gradient-reducing devices in GTE rotor disks

In this paper, we examine experimentally some devices the principle of action of which is based on using the dynamic pressure of air extracted to engine cooling and which are meant for reducing the radial temperature gradient in GTE rotor disks. We established that the devices equipped with the ejector channels make it possible to accelerate the process of the disk hub heating by hot air suction from the cavity periphery towards the rotor axis of rotation. Using the data of visualization studies, we show the possibility for efficient operation of ejector devices in the conditions of real GTE rotor circumferential velocities.     

Optimization of electrode system for the aircraft time-of-flight ion-marking airspeed and angle of attack sensor

A technique of optimizing the electrode system of the differential recorder for the aircraft time-of-flight ion-marking airspeed and aircraft angle of attack sensor by the criterion of ion-marking recording error variance minimum is considered. The technique is based on analyzing the function of spatial distribution for the ion-marking and recorder electrode interaction field potential and determining a point for which this function reaches the maximum slope. The relations making it possible to synthesize the sensor electrode system by the complex criterion as a ratio of error variance to transformation channel response are obtained.     

A lower bound estimate of the critical load for helicopter main rotor composite blade according to the limit equilibrium theory. The basic steps of an algorithm

The basic steps of an algorithm are given for calculating the parameters of the limiting state of a helicopter main rotor blade. To estimate the static strength, a technique of elastic constants variation is used; it is based on the limit equilibrium theory and enables us to obtain the upper and lower bounds for the critical load simultaneously. An iterative technique is proposed to determine the lower bound of the allowable load on the root section of the composite blade depending on the azimuthal angle of its turn in the helicopter hovering mode.     

Analysis of flow past oscillating cascades by the implicit method to evaluate the cascade aeroelastic stability in viscous flow

A technique of analyzing the flutter initiation in flat plate compressor cascades was developed. The viscous and inviscid flow study was carried out using the COBRA solver based on the modified implicit Godunov method and unsteady implicit method updated for using. The flutter conditions were revealed and the effect of taking into account viscosity, angles of attack and time steps was investigated.     

Determination of the influence of a clearance between the case and blade ends of the semi-open impeller on the centrifugal compressor stage characteristics

The influence of the clearance between the case and blade ends of the semi-open impeller on the centrifugal stage characteristics is considered using the experimental data and numerical calculation results.     

Influence of geometry and operating conditions of a centrifugal compressor stage on the radial gas force

The influence of geometry and operating conditions of the centrifugal compressor stage on the radial gas force is determined on the basis of the theoretical method and calculation program using experimental boundary conditions.     

Application of high-order accurate methods to solve the computational gas dynamics and aeroacoustics problems

The application of the low dissipative high-order accurate scheme for numerical solution of the Euler and Navier-Stokes equations in the two-dimensional statement is considered. The scheme of calculating space derivatives is the seven-point central-difference approximation of the fourth order with the coefficients optimized to reduce the dispersion errors. The optimized six-step Runge-Kutta method is used for evaluating the time derivatives. By means of filtration, spurious pulsations are suppressed and shocks are processed. The results of verifying the calculation scheme realized on the stationary problem of flow around the model turbine blades are presented.     

HTPB官能度数学模型建立

为了研究自由基型液体端羟基聚丁二烯预聚物(HTPB)体系官能度分布情况,对其化学合成中自由电子转移情况进行了分析,并通过数学统计的方法对其官能度分布进行理论数值模拟,建立了适用于自由基型HTPB官能度分布的函数关系式,并与GPC所测结果进行对比。结果显示,计算所得函数关系式与测试数据吻合结果较好,数值模拟结果准确性较高;自由基聚合生产的不同批次的HTPB官能度分布存在较大差异,单官能度分子含量可从5%~24%,二官能度分子的含量可从50%~81%;利用数学统计得到的函数关系,可将复杂的HTPB官能度测试转变为简单的分子量分布测试。     

Interplanetary scintillations of the radio source ensemble at the maximum of cycle 24 of solar activity

The results of the interplanetary scintillation observations performed in the period of the maximum of solar activity from April 2013 to April 2014 on the BSA LPI radio telescope at the frequency 111MHz are presented. Fluctuations of the radio emission flux were recorded round the clock for all sources with a scintillating flux of more than 0.2 Jy falling in a strip of sky with a width of 50° over declinations corresponding to a 96-beam directional pattern of the radio telescope. The total number of sources observed during the day reaches 5000. The processing of the observational data was carried out on the assumption that a set of scintillating sources represents a homogeneous statistical ensemble. Daily two-dimensional maps of the distribution of the level of scintillations, whose analysis shows the strong nonstationarity and large-scale irregularity of the spatial distribution of solar wind parameters, were constructed. According to maps of the distribution of the level of scintillations averaged over monthly intervals, the global structure of the distribution of the solar wind was investigated in the period of the maximum of solar activity, which was found to be on the average close to spherically symmetric. The data show that on a spherically symmetric background an east–west asymmetry is observed, which indicates the presence of a large-scale structure of a spiral type in the solar wind.