局部进气裂解油气向心涡轮气动性能分析

Aerodynamic analysis of partial admission radial turbine with cracked fuel vapor

关键词:  局部进气  油气涡轮  向心涡轮  涡轮发电  数值模拟

Key words:  Partial admission  Fuel vapor turbine  Radial inflow turbine  Turbine power generation  Numerical simulation

摘要:

为解决低进气量条件下油气涡轮功率与效率提升困难的问题，本文结合裂解油气物性特点，针对性地提出了局部进气裂解油气向心涡轮设计方案。通过数值仿真详细分析了向心式油气涡轮在设计工况下的内部流动特征，并总结了非设计工况下轮周效率随压比、转速以及正癸烷裂解度的变化规律与影响机制。仿真结果表明，本文所设计油气涡轮在0.5 kg/s进气量条件下可实现38.8 kW功率输出，轮周效率为68%，能够满足油气涡轮气动设计需求。根据结果分析可知，随着压比的增大，轮周效率呈现出先增大后减小的趋势：低压比条件下轮周效率增大主要与转子入口攻角损失有关；高压比条件下轮周效率降低则主要是由于激波损失及其引发的附面层分离损失不断增大导致的。研究表明，轮周效率随转速、裂解度发生变化时与转子入口攻角有直接关系，其中，油气工质裂解度每提高20%，涡轮轮周效率可提高13%左右。

Abstract:

To achieving high power output and high efficiency of the cracked fuel vapor under the condition of low intake， the scheme of the partial admission radial inflow fuel vapor turbine is proposed based on the working capacity analysis of the cracked fuel vapor. The internal flow characteristics of the radial vapor turbine under the design condition are examined by numerical simulation， and the influence of pressure ratio， speed， and conversion of n-decane on rim efficiency under off-design conditions are summarized. The simulation results show that the turbine designed in this paper can achieve 38.8 kW power output under the condition of 0.5 kg/s flow intake， and the rim efficiency is 68%， which means a high-level aerodynamic preference and meets the design requirements very well. The results show that as pressure ratio rises， rim efficiency initially rises and subsequently declines： the increase of rim efficiency under low pressure ratio is mainly related to the loss of rotor incidence angle， while under high pressure ratio， the decrease of rim efficiency is mainly caused by the increasing shock loss and the resulting boundary layer loss. The variation of rim efficiency with rotational speed and conversion of n-decane is directly related to incidence angle， and when the conversion increased by 20%， the rim efficiency can be increased by about 13%.