No abstract

In experimental fine-tuning of aircraft and ground-based gas turbine engines the gas-air line pressure oscillations is a highly informative parameter. Because of high temperatures and vibration levels the pressure sensors do not meet tolerances and thus they are connected to the measuring point by supply channels forming an acoustic probe. The resonant pressure oscillation amplification in the probe, reducing the accuracy of the measurement, occurs if no correction elements are used. Applicable correction elements in the form of long lines are of limited use due to their large size. The authors suggest corrective compact devices capable of measuring the acoustic pressure oscillations by the probe in a wide range of medium pressure. The corrective devices are implemented as a set of capillary channels and a porous MR throttle made of 0,09 mm diameter wire spiral by mold compression regulated by the average acoustic pressure. The technique of selecting parameters and design of the corrective devices are presented herein.

ABSTRACT

Test stand for function optimization (incomposition ofgas-dynamic circuit (GDC)) of operating characteristics of full-size discharge chamber of flowing TEA C07-lasers (power up to 1 00 kW) was created in Samara State Aerospace University ( former Kuibyshev Aviation Institute).Test stand includes an inside-type GDC, low inductive generators of voltage pulses of preionization and main discharges, two-flow rate system ofgas supply and noise immunity diagnostic system.Module construction ofunits ofGDC, power supplies ofpreionization and main discharges allows to change configuration of stand's systems for providing given properties of gas flow and its energy supply.This test stand can also be used in servicing of laser system. The diagnostic system ofthis stand allows to analyze energy properties ofdischarge by means of oscillographic measurements of voltage and current with following processing of discharges' volt-ampere characteristics by means ofa computer; rate ofnon-stationary gas-dynamic disturbances in discharge gap ofdischarge chamber was measured by means of pulse holographic system (UIG-I M) with data processing of schliren-and interferogram (density fluctuation sensitivity --Ift2) and sensor measurement system ofgas-dynamic shock and acoustics process with resonance frequency exceeding 100 kHz.Research results of process of plasma plate wave and channel structures interaction with mediums, including actuation non-stationary gas-dynamic flows, cavitation erosion ofpreionization electrodes' dielectric substructure, ancillary heating ofchannels by main volumetric discharge are presented as well.Keywords: wave and channel structure, pulse-periodic mode, dielectric substructure, discharge chamber, active medium.A whole series ofscientific and technological problems requires the creation ofshort pulsing TEA C02-lasers with radiation energy up to 1 kJ and pulse time (0,5 --I ,5) . 1 ft6 sec, working in pulse-periodic mode (PPM) with the frequency of recurrence ofpulses 20 Hz . Such highenergy lasers can be created on the basis ofwell-known works in the field ofmonopulsing wideaperture gas-discharge systems of excitation of the self-sustained volumetric discharge (VD)46. However the conversion in these systems to PPM meets a series ofdifflculties, it's connected with their VD high sensitivity the rest ofthe disturbances ofgas environment density .We have created the test stand ( fig. 1) for reduction of expenses on designing and reduction of terms of the development of wide-aperture discharge chambers (WDC) with PPM, which also allows to carry out functional optimization in the composition of gas-dynamic circuit (GDC) of the working characteristics of full-size discharge chambers with volumetric energy input (to molecular gases of 194 SPIE Vol. 2989 • 0277-786X/971$1O.OO Downloaded From: http://proceedings.spiedigitallibrary.org/ on 06/29/2016 Terms of Use: http://spiedigitallibrary.org/ss/TermsOfUse.aspx

Pressure and flow ripple generated by a fuel pump have essential impact on static and dynamic performances of an engine control system. It is especially dangerous for open-loop control used at a turbojet starting mode. The fuel consumption deviation at the engine starting caused by nonlinear averaging of fluctuations over throttling elements can reach up to 25% of a nominal value and provoke engine stopping. In the paper, the method for calculation of the hydro mechanical system characteristics in the presence of fluid born noise and its application for the turbojet start control system are developed. The harmonic analysis and the least mean square (LMS) method for the restrictor performance linearization is used. To avoid influence of fuel flow disturbances on the engine static performance it is proposed to increase system accuracy at the starting mode by placing the hydraulic RL-filter into the control unit. The effect of the device was surely verified by the engine test results.