Simulation and Experimental Research on a Fluidic Oscillator with a Deflector Structure

In the exploitation of deep geothermal energy from hot dry rock (HDR) reservoirs, traditional drilling methodologies exhibit a retarded penetration rate, posing a significant impediment to efficient energy extraction. The fluidic DTH hammer is recognized as a drilling method with potential in hard formations. However, a low energy utilization was observed due to the substantial fluid loss in the fluidic oscillator (the control component of a fluidic hammer). In order to reduce the energy loss and improve the performance of fluidic hammers, a fluidic oscillator with a deflector structure is proposed in this paper. Utilizing Computational Fluid Dynamics (CFD) simulations, the optimal structural parameters for the deflector structure have been delineated, with dimensions specified as follows: a = 13.5 mm; b = 2.0 mm; and c = 2.2 mm. Subsequently, the flow field and the performance were observed. The maximum flow recovery of the output channel of the deflector structure increased by 9.1% in the backward stroke and 3.6% in the forward stroke. Moreover, the locking vortex range is expanded upward, which improves the wall attachment stability of the main jet. Finally, to substantiate the numerical findings and evaluate the practical efficacy of the deflector structure, a series of bench tests were conducted. According to the results, compared with the original structure, the average impact frequency can be increased by 5.8%, the single average impact energy increased by 7.5%, and the output power increased by 13.8%.