Optimization Study of the Dump Diffuser in Gas Turbine to Reduce Pressure Loss

Abstract

As a key component-connecting compressor and the entrance of combustion chamber, the diffuser is able to increase the pressure and slow down the airflow in order to promote efficient combustion as well as avoid a large amount of pressure loss. In this paper, experimental investigation and numerical studies have been carried out to understand the effects of air bleeding from dump region and dump gap ratio on the total pressure loss and static pressure recovery of the dump diffusers. The ultimate objective is optimizing the dump diffuser design to get the maximum static pressure recovery and minimum total pressure loss. A simplified test model is used to study the effect of the air bleeding from the outer dump region and the dump gap ratio on the total pressure loss and static pressure recovery in the dump diffuser. The impact of the dump gap ratio in the performance of the dump diffusers has also been discussed. Nearly all the pressure raise occurs in the prediffuser, and most of the total pressure loss occurs in the dump region. For the recirculating area in the dump region, the controllable vortex can be introduced. Bleeding air from the outer dump region can improve the velocity distribution near the flame tube. The results show that when 0.4% of the air is bled from outer dump region, the performance of the dump diffuser is optimal. Hence, the controllable vortex method is effective for improving the performance of the dump diffuser.

Impact of pressure drop in combustion chamber on gas turbine performance

“…It makes an essential difference because the real pressure drop in combustion chamber is on a level of 2-5% for big power turbines up to 5-10% for small ones [5,10].…”

“…The pressure drop in combustion chamber is an uncertainty which should be estimated, calculated or measured for the possibility of delineation the parameters of gas turbine cycle characteristic points [10][11][12]. The cross section through combustion chamber should be as big as possible, so there are a few kind of combustor design, annular, tubo-annular, silo and tubular.…”

CFD simulation of a vortex-controlled diffuser for a jet engine burner

“…The investigation done on a dump diffuser [19], explained that, since the airspeed dispersion at the diffuser exit is inconsistent, the bleed flow through the dump location helps the dump diffuser work better and the ideal bleed rate is between 0.4 and 0.7 percent. It has been discovered that the ideal inlet vortex level and prediffuser angles are required to get an optimum static pressure recovery.…”