Laminar flow control research at TsAGI: Past and present

This paper presents a brief review of activities in laminar flow control being performed at the Central Aerohydrodynamic Institute named after Prof. N.E. Zhukovsky (TsAGI). These efforts are focused on the improvement of the existing laminar flow control methods and on the development of new ones. The investigations have demonstrated the effectiveness of aircraft surface laminarization applications with the aim of friction drag reduction. The opportunity of considerable delaying of laminar-turbulent transition due to special wing profile geometry and using boundary layer suction and surface cooling has been verified at sub- and supersonic speeds through various wind tunnel testing at TsAGI and during flying laboratory experiments at the Flight Research Institute (LII). The investigations on using hybrid laminar flow control systems for friction drag reduction were also carried out. New techniques of laminar flow control were proposed, in particular, the method of local heating of the wing leading edge, boundary layer laminarization by means of receptivity control, and electrohydrodynamic methods of boundary layer stability control.     

Infrared spectrometer PFS for the Mars 94 orbiter

Thin films containing a mixture of aliphatic (glycine) and aromatic (tryptophan or tyrosine) amino acids were exposed to a vacuum ultraviolet radiation (VUV) with wavelenghts 100–200 nm. Dipeptides (glycyl-tryptophan and glycyl-tyrosine) were synthesized in these conditions. We compared the actions of VUV and γ-radiation. Polymerization is an essential step in prebiological evolution and we have shown that this stage probably occured over an early Solar system history.     

Effect of parametric and nonlinear perturbations on statistical dynamics of the Earth’s pole

We study the influence of additive and parametric slowly varying harmonic (at the Chandler frequency and doubled frequency) and stochastic Gaussian broadband perturbations on mathematical expectations, variances, and covariations of oscillations of the Earth’s pole. The influence of perturbations on both regular and irregular stochastic oscillations is considered in detail. Results of numerical experiments are presented. The developed models and software are included into information resources on the fundamental problem “Statistical dynamics of the Earth’s rotation” of Russian Academy of Sciences.     

Some technical aspects of gaseous detonation

This paper briefly describes two attempts to utilize detonative combustion processes to MHD conversion of thermal energy of fuel to electrical energy and bonding of atmospheric nitrogen. For this purpose a continuous impulse detonation chamber with a frequency up to 200 cps was constructed. Using methane-oxygen-nitrogen mixtures the chamber was maintained in stable operation for several hundred hours. Oil was also employed as fuel.Estimates based on experimental data showed that up to 2% of chemical energy of the fuel may be converted into electrical energy. The use of an accelerating nozzle may improve this result.The concentration of nitrogen oxide in combustion products of the detonation wave was higher by 14% than that expected under usual combustion conditions.The advantages of this type of apparatus are: absence of compressors for fuel and oxidant, impulse current generation, low temperatures of chamber walls, and operation over a large range of operating conditions.Problems associated with the effect of the magnetic field on the propagation of the detonation wave are discussed and the possibility of applying the Zeldovich theory to the case of MHD interaction is described. It is shown that the detonation velocity may either increase or decrease depending on the relative orientation of the direction of magnetic field with respect to the detonation wave.     

Roll control of a flight vehicle with the adjustable center of mass

We present the results of analytical research of flight dynamics for a flight vehicle that is controlled by the adjustable center of mass in the vertical symmetry plane. The roll oscillations, which appear perpendicular to the symmetry plane due to technological errors, are eliminated by means of control rocket engines, for which a control law is assigned.     

Route optimization of the aircraft flight

A method of finding the aircraft optimal route by means of task-oriented replacement of the functional being optimized is proposed.     

Control of flight vehicles with the adjustable center of mass

We resolve a problem how to control the longitudinal angular motion of flight vehicles (FV) having a system to displace the center of mass in the transverse direction. A structure is determined and a control law is established to start up and shutdown the engines. Formulas to determine the control parameters are obtained.     

Variations of static loading in single-crystal turbine blades of aircraft gas turbine engines in the course of prolonged service

Some results obtained in the course of statistical analysis of loading in the turbine blades of civil aircraft GTEs over the operating time interval to 11000 hours are presented. These results can be applied to determine the individual service life and are recommended for use in the service life design system.     

Continuum Model for Space Debris Evolution with Account of Collisions and Orbital Breakups

The paper discusses the mathematical modeling of long-term orbital debris evolution taking into account mutual collisions of space debris particles of different sizes. Investigations and long-term forecasts of orbital debris environment evolution in low Earth orbits are essential for future space mission hazard evaluation and for adopting rational space policies and mitigation measures. The paper introduces a new approach to space debris evolution mathematical modeling based on continuum mechanics incorporating partial differential equations. This is an alternative to the traditional approaches of celestial mechanics incorporating ordinary differential equations to model fragments evolution. The continuum approach to orbital debris evolution modeling has essential advantages for describing the evolution of a large number of particles, because it replaces the traditional tracking of space objects by modeling the evolution of their density of distribution.