Research On Cavitation Characteristics And Structure Improvement Of Afterburning Fuel Pump

Cavitation is widely present in hydraulic machinery such as centrifugal pumps.During its operation,it will produce a series of harmful phenomena,such as cavitation damage,pressure pulsation,vibration and noise,etc.,which may even threaten the safe operation of the unit in severe cases.The afterburning fuel pump is the main component of the aero engine’s afterburning fuel system,and its operational stability is very important.The performance of a certain afterburning fuel pump drops sharply due to cavitation during operation.At the same time,cavitation damage was produced at the root of the blade and the wall of the volute tongue,posing a serious threat to the stable operation of the engine.For this reason,this paper conducts a numerical study on the cavitation flow field inside the afterburning fuel pump,and proposes improved measures for the cavitation at the root of the blade and the tongue area,in order to reduce or suppress the cavitation.The main research contents and results of this paper are as follows:1.In order to reveal the cavitation form in the afterburning fuel pump and the occurrence condition of cavitation in the tongue region,unsteady numerical calculation was carried out,and the characteristics of cavitation flow field and pressure transient characteristics in the afterburning fuel pump at different flow rates were analyzed.The results show that under different flow rates,cavitation first appears on the leading edge of the blade.As the cavitation number decreases,cavitation occurs at the root of the blade and the back of the extended blade.The cavitation in the tongue area is at a low cavitation number under 1.2Q_d.Cavitation has a greater impact on the pressure load on the root of the blade surface.The main frequency of the impeller channel monitoring point is the axil passing frequency.The main frequency of the pulsation of the separated tongue monitoring point is the blade passing frequency.Under the 1.2Q_d,the frequency doubling characteristic of axil frequency is enhanced in the pressure fluctuation spectrum of T-1 monitoring point in tongue region.2.Aiming at the cavitation of the afterburning fuel pump blade root,the improvement measures of the arc structure of the blade root are proposed,and the influence of the improvement scheme on the cavitation is numerically analyzed.The results show that under 0.8Q_d,1.0Q_d,and 1.2Q_d,the critical cavitation numbers are reduced by 4.4%,6.0%,and 1.8%respectively compared with the original scheme.The blade root arc structure improved the cavitation performance of the afterburner fuel pump.Under the same cavitation number,the cavitation volume distribution area at the root of the blade is reduced compared to the original scheme.The distribution of vortex cores at the root of the blade is significantly reduced.Cavitation has a greater impact on the root pressure load on the blade surface.The main frequency amplitude of the pressure pulsation in the impeller channel and the tongue area has decreased.3.Aiming at the cavitation in the tongue area of the afterburning fuel pump,and combining its characteristics under 1.2Q_d,the impact of the improved tongue shape on the cavitation of the afterburner fuel pump is analyzed.The results show that under 1.2Q_d,the critical cavitation numbers of the improved scheme Y1-T2with the original impeller and the combined scheme Y2-T2 with the improved impeller are reduced by 7.4%and 9.3%respectively compared with the original scheme,which further improves the afterburning fuel pump cavitation performance.The improved tongue effectively suppresses the generation of cavitation in the tongue area.The vortex core distribution area is reduced compared to the original scheme.When the cavitation number is low,the doubling of the axil passing frequency on the pressure pulsation spectrum at the monitoring point T-1 of the volute tongue is obviously weakened.