Question #1:1 (20pts) The following data below is known for a multistage axial c
ID: 2087195 • Letter: Q
Question
Question #1:1 (20pts) The following data below is known for a multistage axial compressor. The given stagnation properties at inlet can be assumed to be both the static and stagnation values, : po-inlet = 100kPa 0.436m ; Po-500kPa; T^-iniet 296K; dm-const .; R-50%; N-8000rpm: m 50kg /s at Comp - Inlet & Exit at Comp-Inlet: dl-tip-0728m & di-ul at Comp- Exit: 28.8° & Comp- inlet &exit; stagnation temperature& pressure arerelated as 0-exit0-iniet (0.89)y 0-exit 0-inle Determine: a) The flow and loading coefficients ? & ? b) Axial velocity through the stages Cx c) stagnation enthalpy change per stage d) The number of stages required #stages stg Question #1.2 (ats) reasons why the asial compressor 1.2 (5pts) a) Give two strong reasons why the axial compressor is best choice for some application b) Why was the development of the axial compressor slow For air ?-1.4, Cp?1.005 KJ/kg·K and R-0.287 KJ/kg. K.Explanation / Answer
1.2
a) The axial compressor is best choice because
i) An axial compressor has higher flow rate and greater pressure ratio, which results in higher thrust and fuel efficiency
ii) It have a smaller diameter, resulting in lower frontal area, lower blade tip speeds and provides feasibility for an annular combustion chamber
iii). Axial compressors accomodates more airflow than a centrifugal design of the same size
B) Its development took time because of the reasons:
i)It was mechanically less robust
ii) It was aerodynamically much more sensitive to both intake conditions and downstream pressure changes induced by rapid throttle movements.
iii)Above two conditions leaded to blade stalling and resulting surges, which caused catastrophic blade failures.
iv) Pressure increase per row of blades was low, requiring at least 8 rows with intermediate stator blades.
v) Compared to axial compressor a centrifugal compressor was simpler and cheaper to produce, more rugged & tolerant to the varying intake conditions and throttle changes encountered by a flight engine.