###### Abstract
It has been demonstrated through a proof of concept study that micro-mixing with a cross-flow fuel injection system provides miniaturized diffusive combustion that could solve auto-ignition or flashback problems [18]. [PERSON] and [PERSON] proposed ways in their studies to reduce the combustion temperature in the chamber to reduce NOx emission. Six cases of injection method and injector position effect were simulated to understand the combustion performance. Their result showed that the angled air inlet increased the airflow rotation, which improved the mixing intensity of hydrogen and air and reduced the chamber's peak temperature [19]. [PERSON] et al. [20] performed a detailed study on the design and testing of a micromix combustor with recuperative wall cooling. The investigation uses a set of mass and equivalence ratio variations at different temperatures and pressures to carry out exhaust gas analysis on combustion efficiency and stability. Other works on combustion design and mitigation for LH\({}_{2}\) are documented in the references [4; 7; 11; 21; 22]. Figure 1 provides the temperature characteristics of LH\({}_{2}\) and kerosene as a function of the equivalence ratio. The high storage volume issue is a key hurdle to overcome if \(\mathrm{LH_{2}}\) will be successfully used for aero engines, as it has four times the volume compared to jet fuel. Several works reported different configurations and integration of the \(\mathrm{LH_{2}}\) fuel tank in both conventional and unconventional airframes. The critical driver of fuel storage positioning is the airframe and propulsion system configuration. [PERSON] et al. [23] and [PERSON] et al. [10] provide a detailed description of addressing storage configuration for the airframe. Figure 2 shows different \(\mathrm{LH_{2}}\) aircraft with varying designs of storage. In general, the use of liquefied hydrogen as one of the promising fuel options for aero engines is promising and feasible. The foremost consideration in the successful development and deployment of this technology is performance simulation and assessment [24]. Performance assessment is necessary to minimize the risks and costs associated with the test to analyze and evaluate the feasibility of \(\mathrm{LH_{2}}\) at the various technology readiness levels (TRL). It is also important to assess \(\mathrm{LH_{2}}\) compared to jet fuel and other potential fuels to  
Figure 1: Temperature characteristics of \(\mathrm{LH_{2}}\) and kerosene as a function of the equivalence ratio [6]. Figure 2: Liquefied hydrogen aircraft with different tank configurations [10]. see the performance benefit or advantage that LH\({}_{2}\) provides for aero-engine applications. It appears that there are many literary publications in the public domain around LH\({}_{2}\) combinator design and redesign. The few publications on performance comparison focus on the gas path and cycle performance using conventional or unconventional aero engines. For example, [PERSON] and [PERSON] [8] conducted a study on the performance and emissions effect of changing from kerosene to hydrogen fuel on a V2500 aero engine. The study revealed the feasibility of switching from kerosene to LH\({}_{2}\) but that it would require either redesigning the combustion chamber or using an external heat exchanger and a control system redesign. The study also showed a small performance improvement for a conventional aero engine; however, this is dependent on the fuel temperature and cycle configuration. The study also showed reduced emissions and an increase in NOx, in line with the works of [PERSON] et al. [25], [PERSON] et al. [26], and [PERSON] et al [27]. Exergy is another way to understand and compare the performance of LH\({}_{2}\)[28; 29; 30]. [PERSON] and [PERSON] [31] utilized an exergy approach to assessing LH\({}_{2}\) and jet fuel performance, with their result showing that the introduction of LH\({}_{2}\) reduced exergy efficiency, due to the high specific exergy of hydrogen fuel compared to jet fuel.