The present work considers aspects of efficiency improvement of thermal turbomachinery by reducing tip gap losses by injection from the blade tip to the blade gap. For this purpose, a swirling flow is used. Different methods for producing a swirling flow are discussed. It turns out that not all methods normally used for the development of swirling flows are also relevant for the particular case of swirling injection. An analytic modeling is used to get a rough impression of the success of the action a priori. This is an important step in order to make rapid and goal-oriented decisions, especially in early stages of development and to be able to avoid long time and cost intensive actions without success. Analytical modeling is given by mass balance, momentum balance, Bernoulli equation, friction loss account and consideration of Carnot shock loss. Furthermore, the results of the analytical model are compared by means of a three-dimensional computational fluid dynamics simulation, which includes a sink shaped inlet area in terms of a Cartesian geometry, which is completed by the tip gap area. Calculations are carried out using two characteristic Reynolds numbers. Comprehensive parameter variations, including both different angular velocities and injection angles, are carried out. The results of the swirling injection are compared with both a non swirling injection as well as with the corresponding cases without tip gap injection. For a meaningful comparison of the gap flow in relation to its static pressure drop the flow simulations are performed by full wall resolution. It is found that in contrast to the injection without swirl, in which an injection against the direction of the gap flow was more advantageous, now an injection usefully appears in the direction of the gap flow, when the angular velocity exceeds a certain minimum strength. Especially in the field of high angular velocities with injection in the direction of the gap flow significant improvements in efficiency can be achieved. A swirling injection against the direction of the gap flow turns out to be counterproductive. An injection normal to the gap flow can contribute to a reduction of the tip gap mass flow through additional friction losses, but cannot justify the energy necessary to produce the swirling flow. The comparison between the analytical model and the computational fluid dynamics simulation stays in satisfactory agreement in relevant work areas, whereby both the quality of the analytical modeling and the computational fluid dynamics simulation, and thus the efficiency of the swirling injection are additionally ensured. This comparison is carried out not only with respect to the CD value but also with respect to efficiency, to enable a holistic comparison.