Numerical Research on the Safety and Performance of Transonic Compressor with Bleed Air at Multiple Operation State

Abstract

Some provisions in CCAR 33 are directly and indirectly related with the air system of aircraft engines. To certificate the characteristics of air system is an important work for engine airworthiness. Requirements and instructions of air system are issued under the above provisions in CCAR 33. Air system is essential to the safe and reliable operation of the aircraft engines. The bleed air is drawn out from the compressors. The Sec. 33.66 in CCAR 33, which is referred to as "Bleed air system", presents requirements and instructions for the bleed air. Bleed air from the high pressure compressor has taken up 3-5% in the air system, which keeping on growing during recent decades. Therefore, in view of the importance of air system and the bleed location, a new bleeding method with more efficient use of the bleed air is very much needed. In this paper, air system bleed is used for flow control to explore the feasibility of improving compressor performance through removing stator corner separation by bleed air. The transonic single-stage axial compressor Stage35 of NASA is taken as the research object to study the impact of stator bleed rates on the performance of compressor at different rotation speeds. The numerical research shows that bleeding on the stator casing corner can effectively enhance the performance of compressor at different rotation speeds and improve stator flow field.

Aerodynamic limits of gas turbine compressor during high air offtakes for minimum load extension

“…Figure7shows the aerodynamics indicators evaluated using equations (4 -(7). This shows the values obtained for the respective parameters, highlighting that they are within the range for heavy-duty subsonic compressor technology.…”

“…However, CFD studies often focus on aircraft engines configurations, such as Refs [5] [6] [7] [8] [9].…”

“…These works emphasise on the aerodynamic benefits of such an operation (reduced boundary layer and increased efficiency) and stall active control [10]. Air offtakes from transonic NASA Stage 35 of up to 4% of core flow increased the adiabatic efficiency and stall margin by up to 2% and 31% respectively, at various rotational speeds [7]. The CFD study of bleed offtakes on the 6 th stage of a multistage compressor concerning various extraction rates and locations pointed out that the rotor leading edge is the most favourable, with peak efficiency gains of 0.4% at 5% extraction [11].…”

Numerical investigation on the influence of nonuniform tip clearance on rotor tip-clearance flow field structure

“…The aforementioned analysis shows that, at 100 % n cor , the isentropic efficiency numerical simulation data are higher than the experimental ones. The following are the reasons for the errors: (1) Time's impact on the flow characteristics is disregarded by the steady-state computation technique utilized in this investigation; (2) the CFD adopts a single-channel periodic method, and the data exchange at the rotor-stator interface is nonuniformly distributed, whereas in the simulation, the data exchange is uniform [ 30 ]; and (3) the disagreement between the steady-state simulation with ideal gas and adiabatic slip free-wall boundary conditions and the unstable flow within the compressor.…”