Purpose

Usage of gas turbine engines has increased by day due to rising demand for military and civil applications. This case results in investigating diverse topics related to energy efficiency and irreversibility of these systems. The purpose of this paper is to perform a detailed entropy assessment of turbojet engines for different flight conditions.

Design/methodology/approach

In this study, for small turbojet engines used in unmanned aerial vehicles, parametric cycle analysis is carried out at (sea level-zero Mach (hereinafter phase-I)) and (altitude of 9,000 m- Mach of 0.7 (hereinafter phase-II)). Based on this analysis, variation of performance and thermodynamic parameters with respect to change in isentropic efficiency of the compressor (CIE) and turbine (TIE) is examined at both phases. In this context, the examined ranges for CIE is between 0.78 and 0.88 whereas TIE is between 0.85 and 0.95.

Findings

Increasing isentropic efficiency decreases entropy production of the small turbojet engine. Moreover, the highest entropy production occurs in the combustor in the comparison of other components. Namely, it decreases from 2.81 to 2.69 kW/K at phase-I and decreases from 1.44 to 1.39 kW/K at phase-II owing to rising CIE.

Practical implications

It is thought that this study helps in understanding the relationship between entropy production and the efficiency of components. Namely, the approach used in the current analysis could help decision-makers or designers to determine the optimum value of design variables.

Originality/value

Due to rising isentropic efficiencies of both components, it is observed that specific fuel consumption (SFC) decreases whereas specific thrust (ST) increases. Also, the isentropic efficiency of a compressor affects relatively SFC and ST higher than that of the turbine.

中文翻译：

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涡轮机械部件等熵效率对小型涡轮喷气发动机熵产的影响

目的

由于对军事和民用应用的需求不断增加，燃气涡轮发动机的使用量日益增加。该案例导致调查与这些系统的能源效率和不可逆性相关的各种主题。本文的目的是对涡轮喷气发动机在不同飞行条件下进行详细的熵评估。

设计/方法/方法

本研究中，针对无人机使用的小型涡轮喷气发动机，在（海平面零马赫（以下称第一阶段））和（海拔9000米-马赫为0.7（以下称第二阶段））进行参数循环分析）。基于此分析，在两个阶段检查了与压缩机 (CIE) 和涡轮机 (TIE) 的等熵效率变化相关的性能和热力学参数的变化。在这种情况下，CIE 的检查范围介于 0.78 和 0.88 之间，而 TIE 介于 0.85 和 0.95 之间。

发现

增加等熵效率会降低小型涡轮喷气发动机的熵产生。此外，在与其他组件的比较中，最高的熵产生发生在燃烧器中。即，由于 CIE 的升高，它在第一阶段从 2.81 kW/K 下降到 2.69 kW/K，在第二阶段从 1.44 kW/K 下降到 1.39 kW/K。

实际影响

据认为，这项研究有助于理解熵产生与组件效率之间的关系。即，当前分析中使用的方法可以帮助决策者或设计者确定设计变量的最佳值。

原创性/价值

由于两个组件的等熵效率提高，可以观察到燃油消耗率 (SFC) 下降而比推力 (ST) 增加。此外，压缩机的等熵效率对 SFC 和 ST 的影响要高于涡轮机的等熵效率。