Perforated Orifices Research Articles

Research on the erosion law of shale gas casing perforation hole during fracturing

During the fracturing process of shale gas wells, the high-speed injection of sand-carrying fluid throttles at the perforation casing hole, resulting in erosion at the hole, increasing the geometric parameters of the orifice and even producing cracks, affecting the fracturing construction effect and safety. Therefore, the flow field, the movement trajectory of particles and the erosion law of the perforated holes under different displacement and pump pressure were analyzed by using numerical simulation software and Euler-Lagrangian particle tracking theory, and the simulation analysis results were verified by the full-size physical erosion test of the perforated orifice of the casing. The analysis results show that with the increase of displacement, the erosion rate of the eyelet continues to increase, and the erosion rate of the eyelet in the direction of the liquid inlet is significantly greater than that of the bottom of the casing, and the degree gradually decreases in all directions. Increasing the fracturing construction displacement not only increases the erosion rate and diffusion area at the borehole, but also increases the erosion rate of the pipe wall near the borehole, which will accelerate the thinning of the wall thickness of the casing and affect the service safety of the perforated section casing.

Influence of Hole-to-Hole Interaction on the Acoustic Behavior of Multi-Orifice Perforated Plates

Abstract A key factor for developing low-emission combustion systems in modern gas turbines and aero-engines is the acoustic liner's optimized design. Several models are available in the literature for the acoustic impedance of perforated acoustic liners. Most of these impedance models neglect the interaction effect between the orifices. In practice, the orifices are generally closely distributed such that the interactions between acoustic radiation from neighboring orifices can affect their acoustical behavior. The hole-to-hole interaction effect may change the resonance frequency of the resonator due to the nonplanar wave propagation in the cavity, the orifices in the perforated plate, and the near-wall region in the combustor. Considering this effect may help to predict the resonance frequency of the resonator accurately. In this work, a three-dimensional (3D) analytical approach is developed to account for the nonplanar wave propagation in the cavity and orifices on the perforated plate. The present study employs the proposed 3D analytical method to determine the hole-to-hole interaction end correction of multi-orifice perforated plates. Additionally, the hole-to-hole interaction end correction from a series of perforated plates with different orifice radii and spacings is obtained via the finite element method. Perforated plate specimens with different center-to-center hole spacing are tested using an impedance tube. Experimental results show that the resonance frequency is shifted toward a lower frequency with decreasing holes' spacing. The resulting model is compared with the experiments and the end-correction models available in the literature. The comparison shows that the available end-correction models cannot capture the hole-to-hole interaction effect, which is observed in experiments. In contrast, the proposed model can reproduce measurements with high quality. The resulting model demonstrates that the acoustic end-correction length for orifices is closely related to the perforated plate's porosity ratio and orifice radius. The proposed model is readily applicable in the design of multi-orifice perforated plates.

Evaluation of NOx emissions characteristics in a CO2-Free micro-power system by implementing a perforated plate

Ammonia (NH3), as a carbon-free fuel with a high hydrogen content, has been considered as a promising candidate to be applied for transportation, propulsion, and power generation sectors. However, due to the presence of nitrogen atoms, direct combustion of NH3 features a high NOx emission, which could hinder its wide application. Thus it is important to mitigate or minimize these emissions. For this, a three-dimensional (3D) computational model is developed by considering a detailed chemical-kinetic mechanism. The effects of 1) the perforated plate porosity σ, 2) the perforated plate thickness t1, 3) the perforated orifice off-z axis distance d, and 4) inlet thermodynamic pressure Pin are evaluated. Numerical results indicate that σ plays an important role in determining the NO formation. This is the combined effect of the strong species preferential diffusion and low flame temperature within the recirculation zone. Furthermore, varying t1 is shown to affect the NO generation rate due to the varied recirculation zone. Although the flow field is affected by d to some degree, it has a negligible effect on the NO generation. Finally, the emission behavior is found to have a strong dependence on Pin. Approximately 50% reduction of NO emission is achieved as the inlet pressure is varied from 1 to 3 atm. The present work opens up an applicable way to enable low-NOx ammonia-fueled power systems, and some of the findings could be applied for hydrocarbon systems design.

Influence of process parameters on the machinability of nickel aluminum bronze alloy by electrochemical micromachining process – A desirability analysis approach

The machining of Nickel Aluminum Bronze (NAB) via traditional machining methods creates many problems which include wear of the tool, the appalling surface of the finished product, large dimensional deviation, and excessive heat-affected area. These issues can be mitigated by non-traditional techniques such as electrochemical micromachining, electric discharge machining, laser beam machining, and plasma arc machining. Electrochemical micromachining (ECMM) works under the principle of anodic dissolution. Difficult to machine materials can be easily machined by ECMM technique. The micro-domain applications of NAB are found in perforated orifice and pharmaceutical industries. In this study, micro-drilling on NAB alloy was conducted using the ECMM process. The influence of two different electrolytes such as sodium chloride (non-passivating) and sodium nitrate (passivating) while micromachining NAB alloy was analyzed. The response surface methodology (RSM) approach was proposed to obtain the maximum material removal rate (MRR). The output response MRR was analyzed using desirability analysis. The NAB alloy machined with sodium chloride electrolyte was found to have 2.20 times higher MRR than the component machined with sodium nitrate solution.

Acoustic damping performance of coupled Helmholtz resonators with a sharable perforated sidewall in the presence of grazing flow

Helmholtz resonators are widely used in gas turbines and aeroengines, because of its simple structure and high noise damping. To broaden its effective frequency range, two or more Helmholtz resonators could be applied. In this work, systematic studies are conducted to evaluate the aeroacoustic damping performance of two coupled Helmholtz resonators with a sharable perforated sidewall in the presence of a grazing flow. For this, 2D numerical model of a duct with two Helmholtz resonators implemented is developed via solving linearized Navier-Stokes equations in frequency domain. The model is validated first by comparing with the experimental data available in the literature. It is then modified to examine the effects of 1) the perforated orifice width Dx with respect to the back-cavity width Dr, 2) the mean grazing flow Mach number Ma, 3) the flow direction: forward and reverse. It is found that unlike conventional uncoupled Helmholtz resonators, the coupled ones are associated with three or more damping peaks. The local transmission peaks depend strongly on Dx/Dr, Ma and the flow direction in terms of the magnitude and the resonant frequencies. Furthermore, increasing Dx/Dr leads to the secondary peak being shifted to a higher frequency by approximately 100 Hz. However, increasing the grazing flow Mach number gives rise to deteriorated noise damping performance in terms of the local maximum transmission losses by about 10 dB. Finally, the classical theoretical formula ω2=c2S/VLeff fails in predicting the resonant frequencies of the coupled resonators in presence of the grazing flow. The present study help on optimizing the design of coupled multiple Helmholtz resonators in application.

Geometric shapes effect of in-duct perforated orifices on aeroacoustics damping performances at low Helmholtz and Strouhal number.

In this work, experimental studies are conducted to measure the aeroacoustics damping performances of 11 in-duct perforated plates in a cold-flow pipe with a variable Mach number. These in-duct plates have the same porosities but different number N and geometric shaped orifices. Here six shapes are considered, i.e., (1) triangle, (2) square, (3) pentagon, (4) hexagon, (5) star, and (6) circle. It is shown that the orifice shape has little influence on power absorption Δ and reflection coefficient R at a lower Helmholtz number He ≤ 0.0903. However, as He is increased, the in-duct plate with a star-shaped orifice is shown to be with much lower Δ in comparison with that of other plates with different shape orifices. In addition, the perforated orifice with the same shape and porosity but a larger N is shown to be associated with 20% more power absorption at approximately He = 0.1244. Δmax is observed to be approximately 85% at about He = 0.0244, as Ma≈0.029. To gain more insights, the quasi-steady model is applied, depending on the Strouhal number Sr. The transition from quasi-steady flow behaviors to unsteady behaviors occurs at approximately Sr = 0.45. The measured minimum reflection coefficient Rmin occurs at Ma ≈ 0.024. This experimental finding is consistent with the quasi-steady prediction.

Experimental and theoretical studies of aeroacoustics damping performance of a bias-flow perforated orifice

Aeroacoustics damping performance of an in-duct perforated orifice with a bias flow in terms of acoustic power absorption Δ and reflection χ coefficients are evaluated in this work. For this, experimental measurements of a cold-flow pipe system with a diameter of 2b with an in-duct perforated plate implemented are conducted over the frequency range of 100 to 1000 Hz first. The effects of (1) the downstream pipe length Ld, (2) porosity η, (3) bias flow Mach number Ma and (4) the orifice thickness lw are experimentally evaluated on affecting the noise damping performance of the in-duct perforated orifice. It is found that decreasing Ld leads to increased Δmax (maximum power absorption). However, the orifice thickness plays a negligible effect at lower frequency, and a non-negligible role at higher frequency range. The maximum power absorption Δmax and reflection coefficients χmax are found to be approximately 80% and 90% respectively. There is an optimum porosity or Mach number corresponding to Δmax. In addition, Δ and χ are periodically changed with the forcing frequency. To simulate the experiments and gain insights on the damping performance of the orifice with a diameter of 2a, an 1D theoretical model that embodies vorticity-involved noise absorption mechanism is developed. It is based on the modified form of the Cummings equation describing unsteady flow through an orifice and the Cargill equation describing acoustically open boundary condition at the end of the downstream duct. It is shown that Δ and χ are strongly related to (1) the bias flow Mach number Ma, (2) forcing frequency ω, (3) porosity η, (4) and the downstream pipe length Ld. Comparing with the experimental measurements reveals that good agreement is obtained. This confirms that the present experimental and theoretical study shed lights on the optimum design of in-duct orifices.

Experimental comparison of noise dissipation effects of single- and double-layer acoustic liners

Noise damping performances of 12 perforated liners in the configurations of single- or double-layer are studied in this work. Both experimental and numerical investigations are conducted on these perforated liners with different porosities η, thus enabling the open-area-ratio (also known as porosity η) effect being studied. To simulate practical applications for example gas turbine engines and mufflers, adjustable bias and grazing flows are simultaneously applied to these liners. This enables the role of joint grazing-bias flow being evaluated. These liners’ noise mitigating performance is characterized by acoustic power absorption coefficient Δ. And Δ is measured over the frequency range from 200 to 800 Hz. Increasing the Mach number Mg of the grazing flow is found to deteriorate the liners damping performance, while increasing the bias flow results in the maximum Δmax being increased. Additionally, Δ is found to change harmonically with the noise frequency. Furthermore the local maximum of Δ is reduced with increased forcing frequency. Compared to the single-layer perforated liner, the double-layer one shows a higher Δmax and a broader effective frequency range. On the other hand, when the porosities ηi,o of the outer and inner perforated liners are about 1.1%, the noise absorbing performances are found to be dramatically reduced, especially when the forcing frequency is higher. Increasing the porosities ηi,o gives rise to Δmax being dramatically increased and so the effective frequency range. To gain insight on the noise absorbing mechanism and 10% more power absorption capacity associated with the double-layer liners than that of single-layer liner, 2D lattice Boltzmann simulations of in-duct perforated orifices are performed in time-domain. The calculated acoustic power absorption coefficients from these 2 different configurations of perforated orifices are compared. Finally, optimum design of a single-layer acoustic liner is conducted using a frequency-domain model of a lined duct. It is shown that the orifice thickness T and the porosity ηi play critical roles in determining the optimum noise damping performance.

Experimental and frequency-domain study of acoustic damping of single-layer perforated plates

Perforated plates/liners have been widely applied in aeroengines and gas turbines to dissipate unwanted noise. In this work, numerical simulations and experimental study of acoustic damping performance of single-layer perforated plates are conducted. For this, a frequency-domain numerical model is developed via solving 3-dimensional Helmholtz equations. The model validation is performed first by evaluating and comparing the calculated acoustic damping performances of three perforated plates with the experimental results available in literature. These plates are perforated with a number of circle-shaped orifices, which have different porosities σ. Each plate backed by a resonant cavity is placed at the end of a rectangular-shaped pipe with a loudspeaker implemented on the other end. To simulate real engines, a mean flow (also known as bias flow) is applied to pass through the perforated orifices. The effects of 1) the mean flow Mach number Ma, 2) the resonance parameter Q, 3) the porosity σ and 4) the plate thickness T are studied one at a time. Acoustic damping performance of these plates is characterized by using sound absorption coefficient α and specific acoustic impedance z. It is found that sound absorption coefficient α is increased first and then decreased with increased Ma. The real part of z characterizing acoustic resistance/damping is linearly increased, as Ma is increased. However, the imaginary part of z characterizing acoustic reactance remains almost unchanged. It is also found that the presence of the bias flow greatly increases the maximum sound absorption coefficient αmax by approximately 33% in comparison with that of without mean flow. The plate thickness T is shown to shift the frequency corresponding to the maximum sound absorption coefficient. Comparing the present simulation results with the experimental and analytical ones available in the literature reveals that good agreement is obtained at lower frequency range. However, as frequency is increased, the model predicts that the bias flow leads to the local αmax reduced by 15%. The plate with a larger thickness is associated with another local αmax, which is not observed for a lower thickness plate. Finally, experimental measurements of the acoustic damping of 2 single-layer in-duct perforated plates are performed. The frequency-domain model is then applied to simulate the experiment. Good agreement between our experimental and numerical results is obtained.

Experimental study of aeroacoustic damping performance of in-duct perforated orifices with different geometric shapes

In this work, 11 in-duct perforated plates are experimentally tested in a cold-flow pipe. These plates have the same porosities but different number and geometric shaped orifices: (1) circle, (2) triangle, (3) square, (4) pentagon, (5) hexagon, and (6) star. The damping effect of these orifices is characterized by power absorption and reflection coefficient from to. It is found that the orifice shape has little influence on and at lower frequency. However, as the frequency is increased, star-shaped orifice is shown to be with much lower Δ in comparison with that of other shapes orifices. For the perforated plates with the same shaped orifices, increasing does not lead to an increase of power absorption at lower frequency. However, the orifice with the same shape and porosity but larger is found to be associated with more power absorption at approximately. Maximum power absorption is approximately at about, as. The optimum depends on the orifice shape. The present parametric measurements shed light on the ...

Experimental evaluation of noise damping performance of in-duct perforated orifices with different geometric shapes

In this work, 10 in-duct perforated plates are experimentally tested in a cold-flow pipe. These plates have the same porosities but different number N and geometric shaped orifices: 1) triangle, 2) square, 3) pentagon, 4) hexagon, and 5) star. The damping effect of these orifices is characterized by power absorption coefficient Δ and reflection one R from 100 to 1000 Hz. It is found that the orifice shape has little influence on Δ and R at lower frequency (ωa/2π≤700 Hz). However, as ωa is increased, star-shaped orifice is shown to be with much lower Δ in comparison with that of other shaped orifices. For the in-duct plates with the same shaped orifices, increasing N does not lead to an increase of Δ at lower frequency (ωa/2π≤900 Hz). However, the orifice with the same shape and porosity but larger N is found to be associated with 20% more power absorption at approximately 970 Hz. Δ max is approximately 85% around 190 Hz, as Ma≈0.29. The optimum Ma depends on the orifice shape. The present parametric measu...

Atomization of liquids by disintegrating thin liquid films using gas jets

Liquid atomization is useful in many applications, such as engineering, science, pharmaceutics, medicine, forensics and others. In the present research, an innovative methodology and a new device for atomization of liquids into mists of micron and submicron droplets have been developed. The new liquid-atomization method exploits the physical phenomenon of fragmentation of thin liquid films into fine micron and submicron droplets by gas jets. For several tested prototypes, the direct observations using a high-speed visualization technique have demonstrated that bubbles were generated within a liquid and their shells have been subsequently destroyed by applying a mechanical impulse (pressure of a compressed air) once the bubbles came over the liquid surface. The main characteristics of the generated tap water mists have been experimentally measured by means of the laser diffraction technique under various conditions for each prototype. One of the prototype devices allowed obtaining mists containing 90–99% of droplets smaller than 1µm, with the minimum arithmetic and Sauter mean droplet diameters of 1.48µm and 2.66µm, and the 2.64ml/min of droplet flow rate for 3.5bar manometer pressure of atomizing air. The gas to liquid mass ratios (GLR) in the new device are depending on the atomizing tube length and the number of perforated orifices in the tube: more the tube length, hence more the number of perforated orifices, and therefore more liquid droplets will form for the same gas flow rate. The measured GLR values related to 1m length of the utilized atomizing tube were in the range of 0.65–1.06, and for the specifically utilized atomizing tube of 72mm length were among 9.07–14.67. The results of this study demonstrate that the developed method of generation of very fine droplet mists has many advantages over the existing techniques and can be perspective for many practical applications.

Parametric measurements of the effect of in-duct orifice edge shape on its noise damping performance

Acoustic liners perforated with thousands of millimeter-size orifices are widely used in aero-engines and gas turbine engines as an effective noise damper. In this work, experimental investigations of the acoustic damping effect of in-duct perforated orifices are performed on a cold-flow pipe. A mean flow (also known as bias flow) is applied and its flow rate is variable. Emphasis is placed on the effect of the orifice edge shape. For this, 16 in-duct orifices with different edge shapes and porosities are designed and manufactured by using 3D printing technology and conventional laser cutting technique. The damping effect of these in-duct orifices is characterized by using power absorption coefficient Δ and reflection coefficient χ from 100 to 1000Hz. The performances of these orifices are found to be either improved or deteriorated, depending on (1) edge shape, (2) the ratio T/d of orifice thickness to its diameter, (3) the bias flow Mach number, (4) downstream pipe length Ld and (5) porosity η via varying either the number N or surface area Ao of the orifices. In addition, modifying orifice edge does not lead to an increase of power absorption at lower frequency (⩽700Hz). However, as the frequency is increased, the orifice with square (S-type) edge is found to be associated with 10 percent more power absorption. It is interesting to find that T/d over the tested range (≤0.5) has little influence on its damping capacity. However, the mean bias flow Mach number Ma and porosity η are shown to play critical roles on determining the noise damping performance of these orifices. Maximum power absorption Δmax is found to occur at Ma≈0.018, while the optimum porosity corresponding to Δmax is approximately 7 percent. The present parametric measurements shed light on the roles of orifice edge shape, porosity and mean flow on its noise damping capacity, and facilitate the design of effective perforated liners.

Vorticity-involved acoustic damping performance of an in-duct orifice with a bias flow

Acoustic damping performance of an in-duct perforated orifice with a bias flow in terms of power absorption and reflection coefficients are evaluated in this work. For this, experimental measurements of a cold-flow pipe system with a diameter of 2b with an in-duct perforated plate implemented are conducted first. It is shown that the maximum power absorption Δmax and reflection coefficients χmax are approximately 80% and 90%, respectively. In addition, Δ and χ are periodically changed with the forcing frequency. To simulate the experiments and gain insights on the damping performance of the orifice with a diameter of 2a, a 1D theoretical model embodying vorticity-involved damping mechanism is developed. It is based on the modified form of the Cummings equation describing unsteady flow through an orifice and the Cargill equation describing acoustically open boundary condition at the end of the downstream duct. It is shown that Δ and χ are strongly related to (1) the mean flow Mach number, (2) forcing frequency ω, and (3) porosity η = a/b, and (4) the downstream pipe length Ld. Theoretical predictions are found to agree well with experimental measurements. This confirms that the model has the potential to predict the acoustic damping performance of in-duct orifices.

Experimental investigation of the acoustic damping of In-duct orifices with bias flow

Geometry of orifice is investigated by the experiments to evaluate the acoustic damping capacity of orifice plates in a duct. Four kinds of plates with complex orifice shapes are fabricated by using modern 3D printing technology. To characterize acoustic damping performance of these plates, sound absorption coefficient is used as an index determined by using the classical two-microphone technique. It is found that the geometric shapes of the perforated orifices can affect their sound absorption performances, and the damping performances of different shaped orifices depend on the frequency range. The length of downstream duct is also proven to determine the damping performance of perforated plates. The shorter the downstream pipe length, the narrower frequency range corresponding to lower power absorption. Moreover, the bias flow is shown to play a critical role on the sound absorption capacity of orifice plate in the experiments. Sound absorption coefficient is found to increase first and then decreased with increased Mach number.

Numerical and experimental investigation of the acoustic damping effect of single-layer perforated liners with joint bias-grazing flow

As one of the most commonly used acoustic dampers, perforated liners are receiving wide spread interest for reducing engine noise and stabilizing combustion systems. Generally, acoustic liner is a cylindrical sheet with perforated orifices fitted along the bounding wall of the combustor. In this work, the damping performances of seven single- and one double-layer perforated liners with different open area ratios are experimentally investigated. For this, a cold-flow pipe with a lined section is designed. Both grazing (mean flow through the pipe) and bias flows (air flow through the perforated holes) are applied and their flow rates are variable. The effects of the open area ratio η, the joint grazing-bias flow and the number of perforated layers on the liner׳s damping behavior are studied. It is shown experimentally that increasing the liner׳s open area ratio can increase its damping effect at higher frequency in terms of power absorption. In addition, increasing the grazing flow is shown to reduce the maximum acoustic power absorption, while the bias flow can increase the liners damping effect. Furthermore, the power absorption coefficient is varied periodically over forcing frequency. And the local maximum value is decreased with increased frequency. Comparison is then made between the performance of the single-layer liner and that of double-layer one. It is found that the double-layer liner can increase the damping effect at higher frequency range. In order to simulate the liner damping behavior, a time-domain numerical model is used. It is shown that the liner thickness needs to be considered to correct the predicted damping trend so that the estimated acoustic power absorption agrees well with the measured one over the interested frequency range.

Two-dimensional lattice Boltzmann investigation of sound absorption of perforated orifices with different geometric shapes

To gain insight into sound absorption mechanism and to evaluate its acoustic damping performance, two-dimensional numerical simulation of acoustically excited flow through perforated orifices with different geometric shapes is conducted by using lattice Boltzmann method. It is shown that vortex rings are formed when incident sound waves interact with and destabilize the shear layers formed at the orifice rims, and the sound energy is converted into kinetic energy being dissipated by the surrounding air. To quantify the orifice damping performance, sound absorption coefficient is used, which describes the fraction of incident acoustical energy being absorbed. Unlike frequency-domain simulations, the present study is conducted in time domain and the damping behavior of different shaped orifices is quantified over a broad frequency range at a time by forcing an oscillating flow with multiple tones. Comparing the numerical results with those obtained from the theoretical models and experimental measurements, good agreement is observed. And the square-shaped orifice is associated with larger damping effect than that of a rounded one. Finally, parametric study is conducted. It is found that the maximum sound absorption and the effective frequency bandwidth depend strongly on the combination of the bias flow Mach number and the orifice thickness. The successful demonstration reveals that the lattice Boltzmann method has great potential to be applied in aeroacoustics research field.

Study on discharge coefficient of perforated orifices as a new kind of flowmeter

A perforated orifice is promising in measuring flowrates accurately as a differential pressure device. In this study, the discharge coefficient of a perforated orifice, characterizing the relationship between the volumetric flowrate and the pressure drop across the orifice is presented. Different structures are tested experimentally including orifice thickness, porosity, hole distribution and upstream disturbance. For each case, a wide range of flowrate was tested in a horizontal single-phase water pipe with an I.D. of 29mm. For comparison, the discharge coefficient was also obtained for the corresponding standard orifice with the same porosity and thickness. Meanwhile, the effect on the discharge coefficients of the structural parameters was assessed in terms of pressure drop. The theoretical analysis shows that a perforated orifice yields a weaker distortion to the flow than the corresponding standard orifice, indicating a lower pressure drop and a more stable flow field for the former. The experimental results show that the discharge coefficient of a perforated orifice is 22.5–25.6% larger but with a weaker scattering than that of the corresponding standard orifice. Furthermore, a perforated orifice has a lower critical Reynolds number and a stronger anti-disturbance ability. As a flowmeter, the perforated orifice is comparable to the newly developed differential pressure orifices, e.g. V-cone and slotted orifices, but with a simpler structure.

ICONE19-43330 DISCHARGE COEFFICIENT ANALYSIS OF PERFORATED ORIFICE PLATES

As a new device to measure flow rate, performances of perforated orifice plate, especially its discharge coefficient, is studied theoretically and experimentally. First, we disclose the relationship between discharge coefficient and flow structure by a new theory, field synergy theory. Then we design different structures and test their performances experimentally in singlephase water. To further understand the characteristics, we compare the performances of perforated and the corresponding standard orifices. From the results, field synergy theory is applicable to disclose the working principle of all the differential pressure devices. Compared with standard orifices, perforated ones have more stable discharge coefficients and broader application ranges with smaller critical Reynolds number. Many parameters have effect on the performances such as hole diameter, plate thickness, plate porosity, and spatial distribution. Each parameter has not monotonic but complex effect on perforated orifices, which should be optimized for engineering applications.

Packing for regular distribution of liquid phase over the cross-section of column-type apparatuses

The performance of ceramic honeycomb packing with inclined walls, applied as a distribution layer to be placed under a multi-point liquid distributor with regularly perforated orifices, is studied. The distribution layer must have a good spreading ability without increasing the pressure drop. The aim is to create good liquid distribution over the main honeycomb packing layer with vertical walls. Ten packing modifications which differ in height, dimension of holes, wall thickness and wall inclination are studied. The best configuration from the hydraulic and energy saving points of view is shown. Equations are obtained for determination of the liquid phase distribution coefficient and the pressure drop of dry and wet packings.